Telephone

language

News

news center

Home page

Cementing Technology Strategy of Well Ma Shen 1

Release time:

2016-06-05

Classification:

Technical Forum

Summary：Well Ma Shen 1 is an exploratory well deployed by Sinopec Exploration Company in the high part of the road back structure in the Tongnanba structural belt in northeastern Sichuan. The main exploration of the Cambrian Longwangmiao Group and the Upper Sinian Dengying Group. The designed well depth is 8280m, and the actual completed well depth is 8418m. It is currently the deepest well in China, as well as the deepest onshore well in Asia, the deepest vertical well in Asia and the deepest vertical well in Asia. The drilling was started on June 15, 2014 and completed on January 21, 2016, with a drilling cycle of 587 days. Drilling construction team: 90106ZY team; cementing construction team: Zhongyuan Cementing Southwest Project Department; cementing slurry service unit: Sichuan Hongsheng Petroleum Engineering Technology Service Co., Ltd. undertook the cementing slurry technical service for the remaining 7 wells except the first opening.

Sichuan Hongsheng Petroleum Engineering Technology Service Co., Ltd. He Cunliang

Foreword

Well Ma Shen 1 is an exploratory well deployed by Sinopec Exploration Company in the high part of the road back structure in the Tongnanba structural belt in northeastern Sichuan. The main exploration of the Cambrian Longwangmiao Group and the Upper Sinian Dengying Group. The designed well depth is 8280m, and the actual completed well depth is 8418m. It is currently the deepest well in China, as well as the deepest onshore well in Asia, the deepest vertical well in Asia and the deepest vertical well in Asia. The drilling was started on June 15, 2014 and completed on January 21, 2016, with a drilling cycle of 587 days. Drilling construction team: 90106ZY team; cementing construction team: Zhongyuan Cementing Southwest Project Department; cementing slurry service unit: Sichuan Hongsheng Petroleum Engineering Technology Service Co., Ltd. undertook the cementing slurry technical service for the remaining 7 wells except the first opening.

The cementing depth of the well has reached the domestic high index: the first cementing opening Φ φ482.6mm casing depth 959.64m; Second cementing opening Φ 346.08 Φ 339.7mm composite casing depth 4292.85m; Three-opening suspension cementing Φ 273.1mm small collar casing depth 6203.5m, back cementing length 4082.89m; Four-opening suspension cementing Φ φ193.7mm casing depth 7699.0m, back cementing 8418.0 well cementing length 5985.79m; Five Φ 6.m deep. There are many difficulties and difficulties in cementing process and cement slurry technology, which are quite representative in Northeast Sichuan. In particular, the small hole, small gap, high temperature and large temperature difference between the five -4. ultra-deep wells are great challenges and tests for cementing technology and cement slurry technology. The cementing quality of the whole well is qualified, among which, the cementing quality of the four-opening tie-back and five-opening liner is of high quality.

Well Blast Structure of Well Mashen 1

Spuffing sequence	Bit size 'well depth mm'm	Cementing method	Casing size 'lower depth mm'm	Steel Grade	Wall thickness mm	Buckle type	Sealed well section m
Catheter	914.4'50	single stage	720'50		8.0		0-50
open	660.4 '92.73 609.6' 961	single stage	482.6 '959.64	N80	15.88	TP-TLM	0-959.64
Second opening	444.5 '3 232 406.4 '4295	Positive injection and reverse extrusion	346.08'727.14	TP110TS	15.37	TP-CQ	0-727.14
Second opening	444.5 '3 232 406.4 '4295	Positive injection and reverse extrusion	339.7 '4292.85	TP110TS	12.19	TP-CQ	727.14-4292.85
Three open	311.2'6204	Pin-back	282.6 '1518.83	TP110TSS	17.32	TP-NF	0～1518.83
			273.1 '3866.24	TP110TSS	13.93	TP-CQ	1518.83～3866.24
			284.2'4082.89	TP110TSS	18.12	TP-FJ	3866.24～4082.89
		Suspension	273.1 '6203.5	TP110TSS	13.93	TP-NF	4082.89-6203.5
Four open	241.3 '7699	Pin-back	206.4'843.48	TP110TSS	19.05	TP-NF	0-843.48
		Pin-back	193.7 '5985.79	TP110TSS	12.7	TP-CQ	843.48-5985.79
		Suspension	193.7 '6828.51	TP110TSS	12.7	TP-CQ	5985.79-6828.51
		Suspension	206.4 '7699.0	TP110TSS	19.05	TP-FJ	6828.51-7699.00
Five open	165.1 '8418	Suspension	146.1 '7933.47	TP125s	12.34	TP-FJ	7481.92-7933.47
			139.7 '8149.51	SM2250	10.16	Lilac-top top items	7933.47-8149.51
			146.1 '8418.00	TP125s	12.34	TP-FJ	8149.51-8418.00

Geological stratification of the drilled formation

Name of formation					Code	Design formation		actual formation
Boundary	Department	system	Group	Segment	Code	Bottom boundary (m)	Thickness (m)	Bottom boundary (m)	Thickness (m)
Mesozoic	Jurassic	upper system	Suining Group		J3sn	615	615	630
		Zhongtong	Upper Shaximiao Formation		J2s	2075	1460	2077	1447
			Lower Shaximiao Formation		J2x	2345	270	2354	277
			Qianfo Cliff Formation		J2q	2725	380	2730	376
		lower system	arteflow well group		J1z	3120	395	3141	411
	Triassic	upper system	Xujiahe Formation	Five paragraphs	T3x5	3180	60	3193	52
				four sections	T3x4	3260	80	3282	89
				three sections	T3x3	3345	85	3351	69
				Section 2	T3x2	3455	110	3473	122
		Zhongtong	Leikou Slope Group	four sections	T2l4	3505	50	3520	47
				three sections	T2l3	3655	150	3660	140
				Section 2	T2l2	3755	100	3760	100
				A paragraph	T2l1	3925	170	3938	178
		lower system	Jialingjiang Formation	Paragraph IV-V	T1j4-5	4045	120	4070	132
				three sections	T1j3	4225	180	4225	155
				Section 2	T1j2	4395	170	4393	168
				A paragraph	T1j1	4655	260	4644	251
			Feixianguan Formation	four sections	T1f4	4735	80	4738	94
				three sections	T1f3	4935	200	4928	190
				Section 2	T1f2	5475	540	5491	563
				A paragraph	T1f1	5605	130	5766	275
Paleozoic	Permian	upper system	Dalong Formation		P2d	5665	60	5817	51
		upper system	Wujiaping Group		P2w	5795	130	5925	108
		lower system	Thatched Group		P1m	5945	150	6084	159
			Qixia Formation		P1q	6060	115	6184	100
			Liangshan Formation		P1l	6065	5	6188	4
	Sillius	Zhongtong	Hanjiadian Group		S2h	6265	200	6366	178
		lower system	Small river dam group		S1x	6495	230	6604	238
		lower system	Longmaxi Formation		S1l	6815	320	6920	316
	Ordovician	upper system	Wufeng Group		O3w	6820	5	6926	6
		Zhongtong	Pagoda Group		O2b	6850	30	6962	36
		lower system	Meitan Formation		O1m	6900	50	7010	48
	Cambrian system	Zhongtong	Steep Slope Temple Group		∈2d	7040	140	7291	281
		lower system	Longwang Temple Group		∈1l	7402	113	7402	111
			Canglangpu Group		∈1c	7580	178	7596	194
			Fairy Cave Group		∈1x	7650	70	7690	94
			Qiongzhusi Group		∈1q	8080	430	8044	354
Prozoan	Sinian system	upper system	Dengying Group	four sections	Z2dy4	8280	200	8288	244
Prozoan	Sinian system	upper system	Dengying Group	three sections	Z2dy3	8418 (not worn)	138	8418	130

1. opening 482.6mm casing cementing

1. Basic information

1) Well structure (see front)

2) Mud performance

Density: 1.12 g/cm; Viscosity: 78 s; Water loss: 3.8 ml;PH value 9.

3) BHA

Φ 609.6mm ST525CG drill bit float valve 731*830 joint 11 "drill collar * 3 Φ602mm centralizer 831*730 joint 731*731 double male shock absorber 631*730 joint 9 1/2" drill collar * 6 731*630 joint 8 "drill collar * 3 631*520 joint 139.7mm heavy drill pipe * 3 521 * ZY540 joint 139.7mm drill pipe ZY541 * 520 joint square drill pipe.

4) Complicated situations

At the beginning of June 15, 2014, the air drilling reached 65m, and gas channeling was found outside the conduit. On the 16th, the attempt to pull out the conduit and reconsolidate the conduit was unsuccessful. On the 17th, 15m of plugging slurry was squeezed into the well. There was still gas channeling within 30m of the well site, and the plugging was unsuccessful. On the 18th, a cement slurry with a density of 1.92 g/cm was injected into the formation at 15m, and 9.6m, waiting for coagulation. On the 19th, the depth of the plug surface was 30m; After plugging, foam drilling was switched to mud drilling at 893.66m on June 28.

5) Well diameter

If the well is not well logged, the well diameter shall be calculated by expanding the bit size by 10%, that is, the well diameter shall be calculated by 726.44mm.

2. Cementing method

In the original design, dry cementing is used instead of plug-in cementing due to pipe gas channeling and mud drilling.

3. Construction difficulties

1) Soon after the mud is changed, the rock will absorb water and expand, which will easily cause borehole wall instability, block the annulus and affect the sealing quality;

2) The bearing capacity of the upper formation is low, and there is the possibility of leakage during cementing.

3), large casing into a certain risk.

4), large borehole cleaning difficult, low displacement efficiency,

5) Large amount of cement slurry, large amount of slurry replacement and long working time of equipment.

4. Key technology measures:

1), the use of 1.90g/cm3 regular density cement slurry system, to ensure the strength of cement stone.

2) Carefully pass the well and ream the hole. Increase the rigidity of the drilling tool with centralizer to pass through the well to the bottom, confirm that there is no blocking phenomenon, and carry sand with large displacement to ensure smooth running of casing.

3), interpolation method, after the plug is inserted in place, fill the casing with clear water, confirm that the level of clear water does not drop, and then inject water slurry. After replacing the slurry with clear water, pull out the plug and pull out the drill pipe.

4), after the cement injection to the amount, if no cement slurry back out of the ground, then inject 10m3, if still no cement slurry back out, then waiting for 8-12h after the annulus squeeze cement slurry. Ensure that the grout eventually returns to the surface.

5. Casing pipe string

1) Pipe string structure: (from bottom to top)

Lead shoe (0.57m) 482.6mm steel grade N80 wall thickness 15.88mm buckle type TP-TLM sleeve (22.64m) plug-in float collar (0.44m) 482.6mm steel grade N80 wall thickness 15.88mm buckle type TP-TLM sleeve (919.78m).

2) Strength check

Outer diameter mm

Steel Grade

Wall thickness mm

Buckle type

Length m

Weight per meter kg/m

Tired weight t

casing strength

Safety factor

Tensile kN

Anti-extrusion MPa

Internal pressure resistance MPa

Tensile

Anti-extrusion

Resistance to internal pressure

482.6

N80

15.88

TP-TLM

959.64

184

176.6

12839

12.3

31.78

7.12

1.38

3.18

6. Cement slurry

1) Test conditions of cement slurry:

The temperature is 35 ℃; the experimental pressure of cement slurry is 21MPa, the heating and pressurizing time is 30 min, and the thickening time is measured under the condition of constant temperature and constant pressure.

2) Requirements for cement slurry performance

Cement Slurry Density (g/cm3)	Flow degree (cm)	Water loss (ml/6.9 Mpa'30 min)	Thickening time (min)	48h compressive strength (Mpa)
1.90	³22	<150	190-230	³14

7. Cementing

1). Casing running

From 12:00 on July 4 to 11:00 on July 5, 2014, set Φ482.6mm casing to well depth of 959.64m;~ 14:00 circulation; ~ 18:30 drill pipe in place.

2) Cementing

On July 5, 2014, from 18:24 to 18:58, 25m of prepad fluid and 240m of water injection mud at 21:12 were injected, with an average density of 1.86 g/cm (maximum 1.98 g/cm and minimum 1.80 g/cm). The cement mixed slurry just returned to the ground wellhead and lost it. ~ 21:20 Clean water in the drill pipe is replaced, ~ 3:00 drill pipe is picked up for coagulation.

From 22:00 to 22:30 on July 6, 8m of cement slurry with a density of 1.85 g/cm was squeezed into the annulus.

3) Cementing quality

At 3:00 on July 28, 2014, the drill was drilled at 925m to reach the cement surface (float collar position 935.98m), and the cement plug was 10.98m high.

On July 30, 2014, the cementing quality was qualified.

8. Cementing Summary

The plug-in cementing is adopted for large borehole and large casing cementing, which not only reduces the amount of slurry displacement, but also greatly shortens the construction time. Due to the intuitive return of cement slurry, the cementing quality is easily guaranteed.

Cementing of 346.1 339.7mm casing in the second opening of 2.

1. Basic information

1) Well structure (see front)

2), mud performance: (potassium chloride polyamine anti-collapse mud system)

Density (g/cm3)	Viscosity (s)	Initial/final cut (Pa)	Mud cake (mm)	Filtration loss (ml/30min)	Sand (%)
1.57	65	3/7	0.5	4	0.2
YP(Pa)	PV(mPa.s)	coefficient of friction	PH	Φ600	Trillion 300
8.5	48	0.78	9	103	60
Foam drilling to well depth: 1209m

3) Formation breaking test

When the well depth is 3086.12m, the wellhead pressure is 3.2MPa, the mud density is 1.65g/cm3, and the formation is not broken, the equivalent density of the bottom hole is 1.75g/cm3.

4) Pump condition and drilling parameters

Pump No.	Model	Cylinder diameter (mm)	Displacement (L/S)	Pump pressure (MPa)
No. 1, No. 2	F1600	160	28	26

Maximum drilling displacement after mud conversion: 55 L/S, maximum pump pressure: 26 MPa.

5) Drilling tool assembly

Φ 406.4mm SKH616S-A1D drill bit 285.7mm rotary punching tool 831*730 joint 731*731 double male 229mm float valve 244.5mm drill collar * 2 402mm centralizer 244.5mm drill collar * 4 731*630 joint 203.2mm drill collar * 5 203mm curved long shaft 203mm while drilling jar 631*520 joint 179mm valve bypass 139.7mm weighted drill pipe * 12 521 * ZY540 joint 139.7mm drill pipe

6) Complicated situation-lost circulation

Well leakage occurred at the well depth of 3232m during the second sputoff. Mud performance: density 1.64g/cm3, viscosity 64S, water loss 4ml, PH 8, shear force 2/9pa. From 18:00 on October 31, 2014 to 10:30 on November 9, 2014, the total loss time was 208.5h, the leakage mud was 410.92 m and the plugging slurry was 118.28 m, totaling 529.2m. The analysis shows that the formation pressure window in the well section of Xujiahe Formation is narrow, and the occurrence of lost circulation is caused by insufficient formation pressure bearing capacity.

7) Data of well diameter and well deviation

Well diameter: according to the electrical logging data, the well diameter of 444.55mm bit is 463.12mm, and the well diameter expansion rate is 4.2; The well diameter of 406.4mm bit is 427.61mm, and the well diameter expansion rate is 5.2.

Well deviation: the maximum well deviation is 3.1 °/3394m.

Dogleg degree: maximum 2.01/3137m.

8) Oil and gas display

From 2251m to 3536m, a total of 30 gas display layers were found, of which 13 layers were more obvious:

Serial Number	horizon	Well interval m	Thickness m	Total hydrocarbon%	Mud parameters				Groove surface display	On-site explanation
Serial Number	horizon	Well interval m	Thickness m	Total hydrocarbon%	Density g/cm3	Viscosity s	CL-mg/l	Temperature ℃	Groove surface display	On-site explanation
8	J1z1	3031.00-3033.00	2.00	0.53 ↑ 8.69	1.62 ↓ 1.61	55↑56	51475	73	Bubbles 1%	coal bed gas
12	J1z1	3119.00-3120.00	1.00	0.09↑4.95	1.64	54	55735	74	None	coal bed gas
13	J1z1	3125.50-3126.50	1.00	0.41↑5.36	1.65	57	56800	74	None	gas-bearing layer
14	T3x5	3162.00-3163.00	1.00	0.13↑4.24	1.65	55	56090	74	None	Gas in fracture
18	T3x4	3262.00-3263.00	1.00	0.50↑12.08	1.56 ↓ 1.55	54↑56	38340	55	Bubbles 2%	coal bed gas
19	T3x4	3273.00-3278.00	5.00	0.36↑5.87	1.56	57	38695	57	Bubbles 1%	gas-bearing layer
20	T3x3	3286.50-3287.00	0.50	1.95↑9.89	1.57	55	38695	57	Bubbles 1%	coal bed gas
21	T3x3	3298.00-3299.00	1.00	1.04↑11.18	1.57 ↓ 1.56	55↑56	38695	57	Bubbles 2%	coal bed gas
22	T3x3	3308.00-3309.00	1.00	0.85↑8.25	1.56	55	39050	57	Bubbles 2%	coal bed gas
23	T3x3	3344.00-3349.00	5.00	1.06↑8.23	1.57 ↓ 1.56	55	42600	57	Bubbles 1%	Shale gas
27	T3x2	3375.00-3378.50	3.00	1.86↑5.68	1.57	53	42245	59	calcite	gas-bearing layer
28	T3x2	3422.50-3423.00	0.50	0.95↑4.43	1.57	56	46860	57	Bubbles 1%	gas-bearing layer
29	T3x2	3461.50-3463.00	1.50	0.55↑29.89	1.56 ↓ 1.54	67↑69	48990	57	Up 2cm	gas-bearing layer

9) After-effect display

Serial Number	horizon	Drilling depth (m)	Bit position (m)	Location of hydrocarbon reservoir (m)	Gas channeling velocity (m/h)	Total hydrocarbon (%)	Mud parameters		Liquid surface bubble
Serial Number	horizon	Drilling depth (m)	Bit position (m)	Location of hydrocarbon reservoir (m)	Gas channeling velocity (m/h)	Total hydrocarbon (%)	Density (g/cm3)	Viscosity (s)	occurrence	(%)
4	T3x4	3254.12	3249.00	3247.00-3247.50	48.17	1.98↑3.93	1.57	67	None
7	T3x2	3414.05	3414.05	3375.00-3378.00	13.81	0.72↑4.54	1.58	60	None
8	T3x2	3444.05	3442.97	3422.50-3423.00	15.33	0.18 ↑ 2.77	1.56	76	None
9	T3x2	3465.85	3444.35	3461.50-3463.00	197.07	0.85 ↑ 4.63	1.56 ↓ 1.55	67↑69		1
11	T3x2	3472.66	3462.06	3461.50-3463.00	25.42	0.07↑0.93	1.57	67	None
12	T3x2	3472.66	3461.42	3461.50-3463.00	15.84	0.58↑7.72	1.57 ↓ 1.56	73 ↑ 76		1
13	T3x2	3493.26	3407.81	3461.50-3463.00	13.59	0.69↑3.02	1.57 ↓ 1.55	75↑77		1
14	T2l3	3827.10	3517.08	3532.50-3536.00	21.10	0.70↑1.28	1.58 ↓ 1.57	84 ↑ 85	None

2. Cementing method

The original design of graded cementing, the well leakage returns during the construction of primary cementing, and the actual positive injection and reverse extrusion.

3. Main technical difficulties

1), into the well casing ￠ 339.7mm ￠ 346.05mm, floating weight 453 tons, equipment load is heavy; The large casing is rigid and contains gypsum rock in Jialingjiang Group. There is a certain risk whether the casing can be safely put in place.

2), large borehole, large annulus (80.42L/m), long open hole (3333m), cement slurry is easy to mix in the process of migration, high requirements on the anti-pollution of cement slurry; It is difficult to realize turbulent displacement and improve displacement efficiency.

3). Leakage occurs during drilling, and there is risk of lost circulation during cementing.

4) Large amount of ash, large amount of slurry replacement, long construction time and long thickening time will affect the strength of cement slurry to a certain extent.

5), one-time cementing, there is easy leakage, anti-channeling difficult; two-stage cementing, there is a risk that the classification hoop can not be opened normally and the secondary cementing classification hoop can not be closed normally.

6), drilling gas layer is more, long distribution section, cementing anti-channeling task is heavy.

4. Main technical measures

1), the use of two-stage two-setting cement slurry cementing technology, grading hoop in 2700m near the formation stability, well diameter rules, one-stage cementing using double-setting 1.90g/cm3 single density cement slurry system, double-setting interface is 2900m. The cement slurry system with double coagulation and double density is used for secondary cementing, with the tail slurry density of 1.90g/cm3, the lead slurry density of 1.60g/cm3 and the double coagulation interface of 1500m.

2), increase the rigidity of the drilling tool carefully through the hole, the last trip through the hole drilling tool: 406.4 bit 11 "drill collar 1 Ф 402mm spiral centralizer 11" drill collar 1 Ф 402mm spiral centralizer 11 "drill collar 1 9" drill collar 3 8 "drill collar 3 5 1/2" drill pipe, after the hole through the hole to the end, fully circulate to ensure the hole is clean and free of blocking cards.

3), do a good job of formation pressure test, so that the bottom hole equivalent density of 1.72g/cm3 is qualified.

4) Before running casing, use thick slurry to carry sand and fully carry rock cuttings in the well to achieve the purpose of cleaning the well.

5), the selection of continental shelf classification hoop, requiring manufacturers engineers to on-site inspection and downhole use guidance services.

6) 5 sleeves at the bottom are coated with thread glue, and the other sleeves are coated with thread sealing grease. Fill every casing with slurry.

7), reduce the mud viscosity cut to reduce the migration process in the slurry mixing, reduce the sand content, to prevent the small displacement in the first stage of waiting for coagulation or intermittent top through circulation due to sand precipitation blocking the closure sleeve, affecting the classification hoop closure.

8) In order to ensure that the grading hoop can be opened smoothly after the first-level cementing, the cement car will replace 15m3 of protection fluid to the grading hoop during the slurry displacement of the first-level cementing. At the same time, in order to ensure the safety of cementing construction, cement slurry with a density of 1.80g/cm3 is used as transition slurry for 8m3 before the first-class cement slurry.

9) The first-level displacement adopts weighted mud 125 m3 with a density of 1.80g/cm3 to reduce the pressure difference between the inside and outside of the pipe below the grading hoop after the displacement; The second-level displacement adopts the original well slurry.

10), the first level cementing due to the use of flexible rubber plug, cementing without forced pressure, to avoid empty. In secondary cementing, if leakage occurs during cement slurry injection and cement slurry does not return to the ground, cement must be squeezed from the wellhead for remediation.

11), before the construction of all equipment to carry out major inspection, equipment commissioning inspection and rectification before cement injection, to ensure that the construction is continuous and stable. The drilling crew shall check the mud pump, measure the water-filling efficiency, and do a good job of slurry displacement measurement.

12) Leak-proof measures: ① If there is leakage, plug the leakage interval before running casing. ② Strictly control the lowering speed of casing. After the casing is put into the well by stages, the lowering time of each casing shall not be less than 90 seconds, and the lowering time of each column shall not be less than 120 seconds. ③ After the jacking circulation of the casing running with small displacement is normal, adjust the mud performance to reduce the sticking and cutting. ④ Optimize the displacement of ash injection and slurry displacement, and make reasonable adjustment according to the situation of annular return slurry and the change of construction pressure. ⑤ Add appropriate amount of fiber into the primary cementing tail slurry.

13) Formulate specific technical measures and precautions for each link, including: well passage and casing running; casing running tool parameters; grading hoop parameters and use; cementing precautions and emergency measures; casing head mandrel seating; chuck operation.

5. Technical measures for cement slurry

1) Two-setting cement slurry system is adopted for primary cementing: 1.90g/cm3 anti-channeling cement slurry system is used for lead slurry and 1.90g/cm3 anti-channeling cement slurry system is used for tail slurry. Double coagulation interface 2900m. The dynamic shear force of cement slurry is larger than that of slurry, which reduces slurry mixing and improves displacement efficiency.

① Test conditions of cement slurry for first-class cementing

The experimental temperature is 87 ℃, the pressure is 75MPa, and the heating and boosting time is 90min. The thickening time is measured under constant temperature and pressure.

②. Formula of first-class cementing slurry:

　　JHG+BS500(2%)+BS600(1%)+BS100(1%)。

③. Performance of first-class cementing slurry:

2. Cementing method

The original design of graded cementing, the well leakage returns during the construction of primary cementing, and the actual positive injection and reverse extrusion.

3. Main technical difficulties

3). Leakage occurs during drilling, and there is risk of lost circulation during cementing.

4) Large amount of ash, large amount of slurry replacement, long construction time and long thickening time will affect the strength of cement slurry to a certain extent.

6), drilling gas layer is more, long distribution section, cementing anti-channeling task is heavy.

4. Main technical measures

3), do a good job of formation pressure test, so that the bottom hole equivalent density of 1.72g/cm3 is qualified.

4) Before running casing, use thick slurry to carry sand and fully carry rock cuttings in the well to achieve the purpose of cleaning the well.

5), the selection of continental shelf classification hoop, requiring manufacturers engineers to on-site inspection and downhole use guidance services.

6) 5 sleeves at the bottom are coated with thread glue, and the other sleeves are coated with thread sealing grease. Fill every casing with slurry.

5. Technical measures for cement slurry

① Test conditions of cement slurry for first-class cementing

The experimental temperature is 87 ℃, the pressure is 75MPa, and the heating and boosting time is 90min. The thickening time is measured under constant temperature and pressure.

②. Formula of first-class cementing slurry:

　　JHG+BS500(2%)+BS600(1%)+BS100(1%)。

③. Performance of first-class cementing slurry:

Project	Primary collar slurry		Primary Tail Slurry
Project	Design	Actual	Design	Actual
Density (g/cm3)	1.90	1.90	1.90	1.90
Water loss (ml)	≤100	58	≤100	64
24 hours compressive strength (Mpa)	≥14	14.5	≥14	15
72 hours compressive strength (Mpa)	≥14	20.2	≥14	22
Initial consistency (Bc)	≤ 20.0	20	≤ 20.0	20
100Bc thickening time (min)	380-420	388	240-300	246
Density High Thickening Time (1.93g/cm³,min)	380-420	374	240-300	242
Shutdown thickening time (120min shutdown 50min,min)	380-420	383	240-300	/
degree of mobility	≥ 22	22	≥ 22	22

④ Rheological reading of cementing slurry of grade I:

87°C	Φ600	Trillion 300	Φ200	Φ100	Φ6	Φ3
Collar	205	124	95	57	8	6
tail slurry	215	130	105	60	12	9

⑤ Compatibility test of cement slurry for primary cementing

Collar	tail slurry	Flushing fluid	Pilot slurry	Plug fluid	displacement pulp	thickening time
70%		20%	10%			Not thick for 385min
33%		33%	33%			392min not thick
	70%			20%	10%	200min not thick

2) Double-setting double-density cement slurry system is adopted for secondary cementing: low-density expansive cement slurry with density of 1.60g/cm3 is used for lead slurry; anti-channeling cement slurry system with density of 1.90g/cm3 is used for tail slurry. Double condensation interface 1500m.

①. Test conditions for cementing slurry of Grade II:

Temperature 56 ℃, pressure 45MPa, heating and boosting time 70min; Thickening time measured at constant temperature and pressure

②. Formulation of cement slurry for cementing of grade II:

Lead: JHG + BS500(2%)+ BS600(1%)+ BS100(2.6) + PZ(18%)+ WG(2.4) + BS200R-2(1.3) + BS300(0.6)

Tail slurry: JHG + BS500(2%)+ BS600(1%)+ BS100(2%)+ BS200R-2(1.45) + BS300(0.375)

③. Cement Slurry Performance of Grade II Cementing

Project	Secondary collar slurry		Secondary tail slurry
Project	Design	Actual	Design	Actual
Density (g/cm3)	1.60	1.60	1.90	1.90
Water loss (ml)	≤100	64	≤100	60
72 hours compressive strength (Mpa)	≥ 7	10	≥14	23
Initial consistency (Bc)	≤ 20.0	19	≤ 20.0	22
100Bc thickening time (min)	240-330	326	240-330	301
Density High Thickening Time (0.03g/cm3,min)	240-330	243	240-330	245
degree of mobility	≥ 22	22	≥ 22	22

④ Rheological reading of cementing slurry of Grade II:

Name	Φ600	Trillion 300	Φ200	Φ100	Φ6	Φ3
Collar	298	225	175	110	11	6
tail slurry	290	161	143	62	8	5

⑤ Compatibility test of cement slurry for secondary cementing

Collar sample	Tail slurry detail	Flushing fluid	Pilot slurry	Clear Water	displacement pulp	thickening time
70%	-	20%	10%	-	-	287min not thick
33%	-	33%	33%	-	-	Not thick for 363min
-	70%	-	-	20%	10%	120min not thick

6. Casing running

From 14:00 on January 10 to 17:00 on January 12, 2015, the casing was run to a well depth of 3259.37m for circulation, and the casing was run to a wellhead of 3703.59m without returning slurry. The casing was run at 20:00 on the 13th, and the casing shoe was 4292.85m deep.

1) Pipe string structure (bottom-up)

Name	Size × steel grade × wall thickness × button type	Lower depth (m)
Mandrel Hanger		15.57
Double male short joint	F346.08mm×TP110TS×15.37mm×TP-CQ	16.82
Casing	F346.08mm×TP110TS×15.37mm×TP-CQ	726.14
Adapter	346.08mm to 339.7mm	727.14
Casing	F339.7mm×TP110TS×12.19mm×TP-CQ	2700.47
graded hoop	Ф 339.7mm × TP110TS mm × TP-CQ (provided on continental shelf)	2701.59
Casing	F339.7mm×TP110TS×12.19mm×TP-CQ	4248.04
Impact pressure nipples	F339.7mmx 12.19mm×TP-CQ	4248.35
Casing	F339.7mm×TP110TS×12.19mm×TP-CQ	4259.31
Float collar 2	F339.7mmx 12.19mm×TP-CQ	4259.61
Casing	F339.7mm×TP110TS×12.19mm×TP-CQ	4270.13
Float collar 1	F339.7mmx 12.19mm×TP-CQ	4270.44
Casing	F339.7mm×TP110TS×12.19mm×TP-CQ	4292.15
floating shoes	F339.7mmx 12.19mm×TP-CQ	4292.85

2) Performance data sheet of casing of this layer and upper layer

Outer diameter mm	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Outer diameter of coupling mm	Tensile strength kN	Extrusion strength Mpa	Internal pressure strength Mpa
482.6	N80	15.88	TP-TLM	184.00	516	12839	12.3	31.78
339.7	TP110TS	12.19	TP-CQ	101.29	365.13	9514	21.79	47.64
346.08	TP110TS	15.37	TP-CQ	124.34	371.48	11745	35.3	59.0

3) Casing strength check

Open	Outer diameter mm	Serial Number	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Single quantity kg/m	Section weight t	Tired weight t	Safety factor
											Tensile	Anti-extrusion	Resistance to internal pressure
Second opening	346.08	1	0～727.14	727.14	TP110TS	15.37	TP-CQ	124.34	90.40	451.58	2.60	/	/
	339.7	2	727.14～4292.54	3565.40	TP110TS	12.19	TP-CQ	101.29	361.18	361.18	2.63	1.08	1.07

Note:(1) Section weight and accumulated weight are the weight of casing in air, with mud weight of 1.57 g/cm and buoyancy coefficient of 0.80. The external extrusion pressure of the casing is calculated by 30% hollowing, and the internal pressure resistance is 0.66 by the leakage surface.

(2) The floating weight of the casing below the grading hoop is 185.97t, and the tension margin is 270.55t.

4) Placement position of centralizer

Open hole section 959.64 m-4292.85m (bit size 444.5mm), one elastic centralizer for every 6, 35 in total; overlap section 727.14m ~ 959.64m, one rigid centralizer for every 5, 3 in total.

346.08mm casing section (0~727.14m) is thick-walled and thin coupling casing without centralizer.

7. Cement injection and cementing construction

1) First-class positive water injection slurry cementing

On January 13, 2015, a meeting was held at 22:00 to discuss and determine not to plug the leakage. Cementing was carried out on this basis. Construction started at 2:20 on January 14 and ended at 8:10. During the whole construction period, the wellhead has not returned.

Grade I cementing construction record:

Serial Number	Time	Work Content	Liquid density (g/cm3)	Displacement (m3/min)	Liquid volume (m3)	Pump pressure (MPa)
1	14th 2:20~2:40	Pilot slurry injection	1.40	2.5	30	20
2	2:40～2:45	Pipeline pressure test				25
3	2:45～3:00	Flushing fluid	1.02	1.5	16	10
4	3:10～3:17	Collar of primary cement slurry	1.90	2～2.5	10	6 to 8
5	3:17～4:25	Grade I cement slurry tail slurry	1.90	2～2.5	83	6 to 8
6	4:25～4:30	Invert gate, release plug
7	4:30～4:34	Rubber press plug	1.02	1.0	4	0
8	4:35～5:15	replace mud	1.80	2.5	70	2 to 3
9	5:15～5:40	replace mud	1.57	2.5	40	2 to 3
10	5:40～5:50	Car replacement protection fluid	1.02	1.5	15	0
11	5:50～7:05	replace mud	1.57	2.5	202.54	2 to 3
12	7:05～7:10	Impact pressure				4 ↗ 8

Consideration after pressure collision: ① There is no return during the whole construction process; ② The main leakage layer 3232m is below 2700m of the grading hoop; ③ Opening the grading hoop will aggravate the cement slurry leakage of the first-class cementing; ④ There is a risk of casing pressure after opening the grading hoop for cementing; ⑤ Wellhead reverse extrusion cement slurry can be used for cementing the second-class cementing. Decided not to throw the gravity plug and not to open the grading hoop to wait for coagulation.

During the waiting period, from 23:00 on the 14th to 23:00 on the 14th, a total of 51m of glue solution was poured into the annulus four times. ~ 1:00 on the 15th, inject 17m of plugging slurry with a density of 1.56 g/cm and a concentration of 30%.

2) Level II cementing-reverse extrusion of cement slurry at wellhead

①. For the first time, reverse extrusion of cement slurry in the annulus (from 1:00 to 4:00 on January 15)

Construction data of first reverse cement slurry for secondary cementing:

Serial Number	Construction time	Work Content	Liquid density (g/cm3)	Displacement m3/min)	Liquid volume (m3)	Pump pressure (MPa)
1	15th 1:00~1:15	reverse extrusion cement slurry	1.85	1～1.5	20	1-2
2	1:15～2:26	reverse extrusion cement slurry	1.60	1～1.5	106	1-2
3	2:26～4:00	reverse extrusion cement slurry	1.90	1～1.5	141	1-2
4	4:00~2:30 on 17th	Waiting for coagulation

Measurement of annulus liquid level during waiting period:

At 6:00 on January 15, the measured liquid level well depth was 240m; At 7:00, the measured liquid level well depth was 247m.

At 17:30 on January 16, the liquid level monitoring vehicle arrived at the well site to measure the liquid level in the annulus: liquid level 246m at 18:00; 19:00 liquid level 247m;20:00 liquid level 245m;21:00 liquid level 247m;22:00 liquid level 243m;23:00 liquid level 247m;17 0:00 liquid level 245m;17 1:00 liquid level 249m;17 2:00 liquid level 245m.

②. The second annular reverse extrusion cement slurry (January 17, 2:30~3:30) was co-extruded with an average density of 1.90 g/cm cement slurry of 15.8m. The construction was normal, and the cement extrusion was stopped after the ground returned to the water slurry.

From 3:30 on January 17 to 6:00 on January 19, the pressure was suppressed by 10MPa and waiting for coagulation, and there was no pressure drop until the end of waiting for coagulation.

3) Cementing quality:

At 12:00 on January 31, 2015, the sound amplitude was measured electrically, and the annular cement slurry was basically connected. Cementing quality is acceptable.

8. Summary of Second Cementing

1) In case of leakage, the cement slurry is difficult to return to the expected position. Positive injection and reverse extrusion are not infeasible approaches.

2) If the well is cementing in the case of leakage, it is guaranteed to realize the overall tightness of the casing without opening the grading hoop.

3) The displacement of anti-extrusion is as large as possible, and the density of cement slurry is as high as possible, which is good for the quality of the sealing section.

4). The site situation is ever-changing, and some appropriate emergency measures can be taken to ensure safety and cementing quality.

3. three-opening 273.1mm casing suspension cementing

1. Basic information

1) Well structure (see front)

2) Mud performance: (poly-sulfonated anti-collapse mud system)

Density (g/cm3)	Viscosity (s)	Initial/final cut (Pa)	Mud cake (mm)	Filtration loss (ml/30min)	Sand (%)
2.0	61	5/14	0.5	4.2	0.2
YP(Pa)	PV(mPa.s)	CL-	PH	Φ600	Trillion 300
6	44	33725	11	100	56

3) BHA

Φ311.2mmHJT537GK drill bit float valve Φ203mm drill collar × 11 curved long axis jar with drilling 631 × 520 joint Φ179mm bypass valve Φ139.7mm weighted drill pipe × 12 521 × ZY540 joint Φ139.7 drill pipe.

4) Formation breaking test

When the well depth is 4300m, the wellhead pressure is 13.5MPa, the mud density is 2.05g/cm3, and the formation is not broken, the equivalent density of the bottom hole is 2.37g/cm3.

5) Complicated situations

① Well leakage 1: leakage occurred when drilling to a well depth of 5373.30m at 0: 00 on March 2, 2015, and the well leakage was relieved at 10: 00 on March 5. The loss time was 82 hours, and the mud leakage was 151.67 m of 2.02 g/cm.

② Lost circulation 2: leakage occurred when drilling to 6154.45m at 19: 00 on April 20, 2015, and lost circulation was relieved at 2:15 on April 21. The loss time was 7:15, and the lost 2.0 g/cm mud was 20m, 2.0g/cm3 plugging slurry was 15m3.

6) Well deviation and well diameter data

The electric logging results show that there is no irregular borehole such as big belly. However, there are many reduced-diameter sections. The calculated average well diameter is 315.69mm and the well diameter enlargement rate is 1.44%. The maximum inclination angle is 5.74 °/5300m.

7) Pump conditions and drilling parameters

Pump No.	Model	Cylinder diameter mm	Displacement L/S	Pump pressure MPa
No. 1, No. 2	F1600	160	43	29

Note: At present, the maximum drilling displacement is 43L/S, and the maximum pump pressure is 29MPa.

8) Well temperature data

Regional annual average temperature ℃	Ground temperature gradient ℃/100m	Well depth m	Static temperature of bottom hole ℃	Bottom hole circulating temperature ℃
15	2.18	6187	149.87	119.9

Note: The experimental temperature is temporarily set at 120 ℃ (check the bottom hole temperature according to the actual electric logging).

9) Oil and gas display

From 4329m to 6187m, a total of 17 gas display layers were found, of which 8 layers were more obvious:

Serial Number	horizon	Well interval m	Total hydrocarbon%	Mud parameters				Groove surface display	On-site explanation
Serial Number	horizon	Well interval m	Total hydrocarbon%	Density g/cm3	Viscosity s	CL-mg/l	Temperature ℃	Groove surface display	On-site explanation
4	T1f1	5551.00-5554.00	0.09↑4.20	2.00 ↓ 1.99	60 ↑ 62	24850	60	Bubbles 2%	gas-bearing layer
8	P2d	5764.00-5770.00	0.54 ↑ 9.39	2.00 ↓ 1.98	62 ↑ 65	26270	62	Bubbles 10%	Fracture gas
9	P2w	5868.00-5868.50	0.36↑3.67	2.00	58	28755	62	None	Gas in fracture
10	P2w	5885.00-5885.50	0.84 ↑ 4.88	2.00	60	28755	62	None	Gas in fracture
11	P2w	5892.00-5892.50	0.55↑4.27	2.00	58	28755	62	None	gas-bearing layer
12	P2w	5893.00-5898.50	0.81↑16.79	2.00 ↓ 1.97	58↑60	29820	62	Bubbles 2%	Fracture gas
13	P2w	5905.00-5906.00	1.35↑9.33	2.00	58↑60	30175	62	Bubbles 1%	gas-bearing layer
17	P1l	6186.00-6187.00	0.84↑3.98	2.00	63	33725	64	None	Micro-gas

10) After-effect display

Serial Number	horizon	Drilling depth (m)	Location of hydrocarbon reservoir (m)	Static time (h)	Gas channeling velocity (m/h)	Total hydrocarbon (%)	Mud parameters		Liquid level
							Density (g/cm3)	Viscosity (s)	Bubble		Rise (m3)
							Density (g/cm3)	Viscosity (s)	occurrence	(%)	Rise (m3)
1	P2d	5840.60	5764.00-5770.0	37.00	9.31	0.65 ↑ 2.53	1.98 ↓ 1.97	64 ↑ 65	pinhole shape	1	None
2	P1m	6004.10	5905.00-5906.0	32.00	22.57	1.16↑4.49	2.00	67↑68	None		None
3	P1q	6113.06	5893.00-5898.5	40.50	12.83	0.49 ↑ 4.58	2.00 ↓ 1.97	71 ↑ 72	None		None

2. Main technical difficulties

1) The lower well section has gas display under the mud density of 2.0 g/cm, and the gas pressure is high. The weight loss of cement slurry during the waiting process will lead to gas channeling. Anti-channeling is the difficulty of this cementing.

2) During the drilling process, leakage occurred at 5373.30m in the second section of the flight and 6154.45m in the Dalong group, and leakage occurred in the Qixia group. Leakage prevention is the difficulty of this cementing.

3), in the same section of open hole, high pressure gas layer and low pressure leakage layer coexist, the safety window is narrow, pressure stability and leakage prevention is difficult to take into account, is the difficulty of cementing design and construction.

4), the front liquid and cement slurry are high density, on-site mixing device, mixing pump injection technology requirements are high.

5) The density difference between cement slurry and mud is small, the annular space gap at the liner hanger is small, the construction pump pressure is high and the displacement is limited, and the suspension section is all small coupling casing cannot be installed. The centralizer casing is moderately low, which affects the displacement efficiency.

6) The bottom hole temperature is high, the sealing section is 2120m long, and the temperature difference between the upper and lower parts is large (calculated as 45.6 ℃ according to the geothermal gradient). The strength of the upper cement slurry develops slowly under low temperature conditions, and even super retarding occurs.

7), cement slurry weighting material and cement density difference is larger, the slurry is easy to settle, unstable, cement slurry settlement stability, strength, rheology of the coordination between the three more difficult.

8), Φ311.2mm well at the right angle of Φ273.1mm casing, the annular space is small, the casing is difficult to be driven in, and the drilling tool pulling margin is small, the safety of the drilling tool is the focus of attention.

3. Main technical measures

1) Anti-channeling measures:

① Two condensation cement slurries, the two condensation interfaces are at 5200m of the upper 300m of the main gas layer;

② Tail slurry with good anti-channeling performance of latex cement slurry system;

③ Calculation of annulus pressure stability and design of waiting setting shall be carried out, and the slurry column shall be designed reasonably to ensure the safety of pressure stabilized gas reservoir and well control.

④ Before cementing, it is required that the upward channeling speed of oil and gas shall be less than 10 m/h and the density difference between inlet and outlet shall be less than 0.02g/cm3;

⑤ Add back pressure at the wellhead during the waiting period to supplement the pressure loss of cement slurry.

2) Leak-proof measures:

① For formation pressure test, the 2.10 mud shall be circulated for more than two weeks with a displacement of 30L/s, and no leakage is considered as qualified.

② Control the lowering time of casing and drilling tools, no less than 45s for a single pipe and no less than 2min for the column to prevent stratum bouncing and leakage due to excessive exciting pressure; assign special personnel to observe the slurry return situation, check the replacement amount, and deal with any abnormality in time.

③ After the casing is driven down to the designed well depth, start the pump to control the pressure and circulate with a small displacement of 5MPa, and gradually increase the displacement after the circulation is sufficient to prevent leakage of the formation.

④ Add appropriate amount of plugging fiber into the prefluid and cement slurry.

3) Technical measures to improve displacement efficiency:

① Before cementing, lift the sand with thick slurry, flush the well sufficiently to ensure that the borehole is free of sand sedimentation and the density of the mud inlet and outlet is balanced.

② Before cementing, properly reduce the viscosity of the mud, with a density of 2.0g/cm3, a viscosity of ≤ 60s, and an initial cut of ≤ 6Pa. Improve the flow performance of the mud and improve the displacement efficiency.

③ Before cementing, inject 40m3 of pilot slurry with new cooling, calcium resistance and flushing function, with required density of 2.0g/cm3,≤ 55s, initial cutting ≤ 6Pa and dynamic cutting force ≤ 12Pa.

④ Use flushing type spacer fluid to effectively flush the borehole wall and isolate the mud and cement slurry.

4) Construction safety measures:

① Strengthen the rigid drilling of drilling tools, first single support, then double support, and repeatedly support the well. Short trip and ream shall be done for the sections with trip resistance, stuck well and well section with larger dogleg degree, the well wall shall be regulated, and the well shall be cleaned with large displacement after the well is opened to the bottom;

② Before running casing, make sealing fluid in complex well section.

③ Standard drift diameter gauge shall be used for feeding drill pipes, tools, nipples and casings, and anti-falling objects shall be paid attention to; the inner diameter and chamfer of drill pipe changeover joint shall meet the requirements for safe passage of rubber plugs; strength check and flaw detection inspection shall be done for the string of pipes entering the well.

④ Weigh the drilling tools during the well to provide the basis for losing hands.

⑤ Before cementing construction, the pressure test of 30MPa is qualified, and a set of spare high-pressure pipeline is reserved.

⑥ Control the displacement and adjust the displacement in time according to the change of pump pressure to ensure the construction safety.

5) Other technical measures

① In order to ensure the sealing quality of the overlapping section, it is required to scrape the overlapping section and overlap the tail pipe with the upper casing for 200m. To ensure the sealing quality of casing shoe, 55m plug shall be reserved. In order to ensure the sealing quality of bell mouth, 150m plug shall be reserved.

② The drilling team shall provide accurate measured internal volume of drilling tools. The displacement metering shall be subject to the metering of the mud tank of the drilling team, supplemented by the metering of the pump flushing and cementing flowmeter, to ensure the accuracy of the slurry displacement.

③ In order to improve the quality of cement slurry interface cementation, in front of the cement slurry injection flushing type mud cake curing agent.

6). Measures for adding back pressure

After tripping out the 5 struts, connect the kelly pipe with a pressure of 12MPa and shut in the well for coagulation. Pay attention to the following points when adding back pressure:

① Check whether the pressure gauge is connected with the riser;

② Circularly fill the well with slurry, stop the pump and close the gate plate sealer;

③ Add back pressure with small displacement, and the displacement shall be controlled within 10 flushes/min. Pay attention to measuring the pumping volume of the mud tank, and make records of time, pressure and pumping volume;

④ Each pumping volume shall not exceed 0.5 m3. If the pressure is increased, it is controlled at 5MPa for the first time, and if the pump pressure does not drop after 10min, the value will be increased to 8MPa for the second time, and if the pump pressure does not drop after 10min, the pressure will be increased to 12MPa for the third time. If the pressure remains unchanged, the status quo will be maintained. If the pressure decreases, it will be supplemented to 12MPa.

⑤ If there is no pressure, stop the pump when the first pumping volume reaches 0.5m3, observe for 10min, pump again 0.5 m3, and continue to observe for 10min. If there is pressure rise, follow Step 4. If there is still no pressure, observe for 10min and continue to pump 0.5m3 for observation. The cumulative pumping volume shall not exceed 5m3 (85m is reserved on the plug);

⑥ If the pumping capacity reaches 5m3 and still does not have pressure, report it in time and wait for decision;

⑦ If the rising value exceeds 40%(30MPa) of the bearing capacity of casing and wellhead when waiting for coagulation, report it in time and wait for decision;

⑧ The added back pressure value shall be comprehensively considered according to the actual density of cement slurry, the bearing capacity of formation, the stable density of gas layer and other factors.

4. Cement slurry measures

1) Cement slurry scheme

① Double-setting cement slurry system is used, with a double-setting interface of 5200m. The lead slurry is a weighted anti-gas channeling cement slurry system with a density of 2.10g/cm3; the tail slurry is a latex weighted anti-channeling cement slurry system with a density of 2.10g/cm3.

② Adopt JHG cement with stable performance and good compatibility with admixtures, select weighting materials with less impurities, good particle size distribution and small side effects, and select an admixture system with stable performance, good compatibility and no damage to early strength.

③ Optimized cement slurry formula, water loss ≤ 50ml, with high settlement stability, gas channeling capacity coefficient <3.

2) Test conditions of cement slurry:

The temperature is 120 ℃, the pressure is 125MPa, and the heating and boosting time is 75min; The thickening time is measured under constant temperature and pressure.

3) Cement slurry formula

　　领浆：JHG+BS500(2%)+JZ-II(40%)+GW-1(30%)+BS100L-G(4%)+BS200R(3%)+BS300

-J(1%)+ BP-1A(0.5), liquid-solid ratio 0.32; dry-mix pulping rate 0.61.

　　尾浆：JHG+BS500(2%)+JZ-II(40%)+GW-1(30%)+BS100L-G(3%)+JR(12%)+BS200R

(2.5%)+ BS300-J(1%)+ + BP-1A(1%), liquid-solid ratio 0.32; dry mix pulping rate 0.61.

4) Cement slurry performance

Project	Collar		tail slurry
Project	Design	Actual	Design	Actual
Density (g/cm3)	2.10	2.10	2.10	2.10
Water loss (ml/7 MPa30min)	＜50	36	＜50	20
Free liquid (%)	0	0	0	0
72 hours (90 ℃) top compressive strength (MPa)	≥14	17.3	-	--
48 hours compressive strength (MPa)	-	--	≥14	16.0
Initial consistency (Bc)	≤ 20.0	14	≤ 20.0	17
40-100BC transition time (min)	≤10	1	≤10	1
100Bc thickening time (min)	400-460	459	220-280	235
Density high point 100Bc thickening time (min)	>360	403	>180	228
Sedimentation stability (density difference between upper and lower 2 hours at rest)	≤ 0.02	0	≤ 0.02	0

5) Rheological parameters of cement slurry

Name	Φ600	Trillion 300	Φ200	Φ100	Φ6	Φ3
Collar	235	186	119	76	9	6
tail slurry	221	167	95	52	11	8

6) Compatibility test

Pilot slurry	10%	33%	-	10%	20%	-
Spacer fluid (2.05g/cm3)	20%	33%	-	10%	20%	20%
Mud cake curing agent type I	-	-	30%	10%	20%	-
Mud cake curing agent type II	-	-	20%	10%	20%	-
Cement collar slurry	70%	33%	50%	60%	20%	-
cement tail slurry	-	-	-	-	-	70%
Mud	-	-	-	-	-	10%
thickening time	420min not thick	420min not thick	420min not thick	420min not thick	420min not thick	Not thick for 220min

5. Three-opening suspension cementing construction

1). Casing running

From 20:45 on May 9 to 20:00 on May 10, 2015, 273.1mm casing will be lowered, and the casing will be delivered to the well depth of 6203.5m at 19:00 on May 11. Cycle to 6:00 and 6:10 on the 12th, hold down the ball at 7:25 to 12MPa, and lower the 6.24m suspension weight from 240T↘90T, sitting successfully; Continue to suppress the pressure to 21MPa, the pump pressure drops sharply, and the ball seat is suppressed. Dispense: at 7:50, make 5 forward turns to release the torque without reversing, then make 10 forward turns to release the torque without reversing, then make 20 forward turns to release the torque without reversing, the upper suspension weight without change, the distance is 1.5m, and the handle is successful.

2) Pipe string structure (bottom-up)

Name	Size × steel grade × wall thickness × button type	Lower depth (m)
Hanger	Ф 339.7mm × Ф 273.1mm (provided by continental shelf company)	4087.53
Casing	F273.1mm×TP110TSS×13.93mm×TP-NF	6145.70
Ball Seat	F273.1mm×TP110TSS×13.93mm×TP-NF	6146.07
Casing	F273.1mm×TP110TSS×13.93mm×TP-NF	6157.27
Float collar 2	F273.1mm×TP110TSS×13.93mm×TP-NF	6157.54
Casing	F273.1mm×TP110TSS×13.93mm×TP-NF	6179.95
Float collar 1	F273.1mm×TP110TSS×13.93mm×TP-NF	6180.22
Casing	F273.1mm×TP110TSS×13.93mm×TP-NF	6202.47
floating shoes	F273.1mm×TP110TSS×13.93mm×TP-NF	6203.50

3) Performance data sheet of this layer and upper layer casing

Outer diameter mm	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Outer diameter of coupling mm	Tensile strength kN	Extrusion strength Mpa	Internal pressure strength Mpa
339.7	TP110TS	12.19	TP-CQ	101.29	365.13	9514	21.79	47.64
346.08	TP110TS	15.37	TP-CQ	124.34	371.48	11745	35.3	59.0
282.6	TP110TSS	17.32	TP-NF	115.80	293.50	7825	76	77.4
284.2	TP110TSS	18.12	TP-FJ	118.99	284.2	6089	80.40	67.72
273.1	TP110TSS	13.93	TP-CQ	91.50	293.45	7705	53.37	67.66
273.1	TP110TSS	13.93	TP-NF	91.44	283.00	6173	53.37	67.66

4) Casing strength check

Open	Outer diameter mm	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Single quantity kg/m	Section weight t	Tired weight t	Safety factor
Open	Outer diameter mm	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Single quantity kg/m	Section weight t	Tired weight t	Tensile	Anti-extrusion	Resistance to internal pressure
Three open	282.6 back	0～1518.8	1518.8	TP110TSS	17.32	TP-NF	115.8	178.91	417.13	2.39	1.50	1.01
	273.1 back	1518.8～3866	2347	TP110TSS	13.93	TP-CQ	91.50	212.65	238.22	3.32	1.05	1.18
	284.2 back	3866～4082.9	216.6	TP110TSS	18.12	TP-FJ	118.95	25.57	25.57	30.52	1.18	1.46
	273.1 tailpipe	4082.9～6203.5	2120.6	TP110TSS	13.93	TP-NF	91.44	193.85	193.85	4.30	1.08	1.37

5) Strength check of drilling tools

Outer diameter mm	Steel Grade	Wall thickness mm	Single quantity kg/m	Tensile strength kN	Accumulative weight (empty weight) KN	Accumulative weight (floating weight) KN	tensile coefficient	Tension allowance KN
139.7	G105	10.54	36.79	3096	3303	2456	1.26	640

Note:(1) Hanging first and then connecting back to cementing. The casing strength calculation is based on the Structure and Strength Design of Casing String (SY/T 5724-2008).

(2) The section weight and the accumulated weight are the weight in the air, and the safety factor takes into account the buoyancy factor. The anti-extrusion strength is calculated according to 40% hollowing.

6) Centralizer

All small coupling bushings cannot be added with centralizer.

7) Cementing

May 12 7:50~13:00 cycle. 13:30~16:45 cementing, slurry displacement without pressure. ~ 18:15 trip out of 15 columns; ~ 20:45 cycle; ~ 21:15 trip out of 2 columns; ~ 6:00 add back pressure and suppress pressure to wait for coagulation.

Cement injection construction record

Sequence	Construction time	Operation content	Workload (m3)	Density (g/cm3)	Displacement (m3/min)	Pressure (MPa)
1	13:20～13:30	Manifold pressure test				30
2	13:30～13:57	Pumping Pilot Slurry	40	2.15	1.5	15
3	13:57～14:12	Vehicle injection barrier fluid	15	2.05	1.0	15
4	14:12～14:14	Car injection mud cake curing agent type I	2.0	1.02	1.0	16
5	14:14～14:18	Car injection mud cake curing agent type II	4.0	1.02	1.0
6	14:25～14:52	Car injection lead slurry	40	2.10	1.5	16
7	14:55～15:16	Vehicle injection tail slurry	32	2.10	1.5	13
8	15:16～15:18	Release the drill pipe rubber plug
9	15:18～15:20	Replacing the plug fluid	2	2.05	1.0	5
10	15:20～16:11	Pump to replace mud	91.0	2.0	1.8	8-17
11	16:11～16:20	Roof protection fluid	7	2.05	0.8	5
12	16:20～16:42	Pump to replace original mud	38.7	2.0	1.8-1.0	8-22
13	16:42～16:45	Impact pressure				Not pressed
14	16:45～16:50	Unloading cement head
15	16:50～18:15	tripping (tripping to the well depth of 3650m)	15 Pillar
16	18:15～20:45	Circulating well flushing
17	20:45～21:15	Tripping out (to well depth of 3591.8m)	2 Pillars
18	21:15-15 18:00	Well shut-in, pressure bouncing and waiting for coagulation	4.05		6	12

8) Cementing quality

① On May 16, 2015, at 11:00, drill down to a well depth of 3736.32m and probe into the upper plug (with a height of 347.67m)

② On May 30, 2015, at 3:00, drill down to a well depth of 6136m and reach the plug (10m high).

③ Sound amplitude shall be measured from 6:00 to 10:00 on May 20, 2015; the cementing quality is qualified.

6. Summary of Three-opening Suspension Cementing

The suspension cementing quality is qualified, but not high quality. The main reasons are:

1) All small coupling casings of the tail pipe cannot be without centralizer, the casing centering degree is extremely low, and the cement ring is uneven;

2) The gas layer is active, the oil and gas channeling speed is high before cementing, the well slurry density is low, and the pressure is not stable.

3) The flushing dose is too small, the flushing effect is not good, and the interface cementation quality is not very good.

4. three 284.2, 282.6, 273.1mm casing back cementing

1. Technical difficulties of back-up cementing

1) Whether the tieback plug can smoothly enter the tieback barrel and achieve effective sealing is the key to cementing.

2), to achieve the back plug seal at the same time to ensure that the wellhead has enough sitting tonnage, the requirements of the set of residual calculation is accurate.

3) The first sealing section is long, and the temperature difference between the upper and lower is large, which requires high development of early strength of cement slurry.

2. Main technical measures for cementing

1), adjust the mud performance, density 1.70g/cm3, viscosity less than 60s, dynamic shear force less than 8Pa.

2) Scrape the upper casing to eliminate mud cake and ensure the cementing quality.

3), milling back to the cylinder, conducive to the plug to achieve effective sealing.

4) Carefully add the casing centralizer to effectively center the casing.

5), prepare short casing of different lengths, according to the test insertion records of different tonnage pipe string compression distance, adjust the sleeve surplus, so that the back to the cylinder sealing pressure is not less than 20t, casing head mandrel sealing pressure is not less than 150t.

6), adhere to the large displacement construction, improve the displacement efficiency of the slurry.

7), the use of prestressing technology cementing, in the annulus pressure 10MPa waiting for coagulation.

3. Main technical measures for cement slurry and preliquid

1), cement slurry, front fluid technology

① In order to ensure the cementing quality, the regular impermeable anti-gas channeling cement slurry with a density of 1.90g/cm3 is used in the upper part, and the elastic-plastic cement slurry with a density of 1.90g/cm3 is used in the lower part of 20m3. In order to ensure that the pressure difference between the inside and outside of the pipe is within 10Mpa, the mud density of 1.70g/cm3 is used for replacement.

② Use Jiahua Class G oil well cement to control the water loss of cement slurry ≤ 100ml.

The use of good rheology, good stability of the expansion toughness cement slurry system, improve the quality of sealing.

④ Use high-quality high-dose flushing liquid system 40m3 to ensure good flushing effect.

⑤ Appropriately add cement slurry volume, increase the contact time of wellhead section, and improve the strength of wellhead cement stone.

2) Test conditions of cement slurry:

The temperature is 80 ℃, the pressure is 80MPa, and the heating and boosting time is 90min. Measure the thickening time under constant temperature and pressure.

3) Cement slurry formula:

　　JHG+BS500(2%)+BS600(1%)+BS100(0.5%)+BS100L(3%)+BS200R(2%)+BP-1A(0.5%)

Liquid-solid ratio 0.44; dry mix pulping rate 0.76.

4) Performance of cement slurry:

Project	Design	Actual
Density g/cm3	1.90	1.90
Water loss ml/7MPa × 30min	≤50	48
72h compressive strength MPa	≥14.0	19.8
Initial consistency Bc	≤20	18
100Bc thickening time min	300～360	358
Free fluid%	＜0.5	0

5) Rheological parameters of cement slurry

Name	Φ600	Trillion 300	Φ200	Φ100	Φ6	Φ3
cement slurry	225	162	96	50	6	4

6) Compatibility test

Cement slurry, flushing fluid and mud each 33%:300min not thick; Cement slurry 70%, flushing fluid 20%, mud 10%:300min not thick.

4. Three-opening and back-connecting cementing construction

1). Casing running

Casing from 12:30 to 2:00 on May 22, 2015; ~ 5:00 try to insert, adjust pipe string and lower mandrel.

2) Pipe string structure (bottom-up)

Name	Size × steel grade × wall thickness × button type	Lower depth m
Mandrel	F273.1mm×110TSS×13.93mm×TP-CQ	14.53
Double male short joint	F282.6mm×110TSS×17.32mm×TP-NF	17.53
Casing	F282.6mm×110TSS×17.32mm×TP-NF	1517.02
Transition Section	282.6mmTP-NF female × 273.1mmTP-CQ male	1518.83
Casing	F273.1mm×TP110TSS×13.93mm×TP-CQ	3865.48
Transition Section	273.1mmTP-CQ female × 284.2mmTP-FJ male	3866.24
Casing	Ф284.2mm×TP110TSS×18.12mm×TP-FJ	4038.45
Variable buckle nipple	F284.2mm×18.12mm×TP-FJPE×F282.6mm×17.32mm×WSP-FJ公	4039.48
throttle float collar	Ф282.6mm×110TSS×17.32mm×WSP-FJ	4039.76
Variable buckle nipple	F282.6mm×17.32mm×WSP-FJPE×F284.2mm×18.12mm×TP-FJ公	4040.98
Casing	Ф284.2mm×TP110TSS×18.12mm×TP-FJ	4081.42
Return plug		4082.89

3) Placement of centralizer

Top depth of well interval (m)	Bottom depth of well section (m)	Centralizer type	Centralizer specification (mm)	Placement spacing (m)	Placement quantity (only)
0	1517.02	Centralizer cannot be added to small coupling casing
1517.02	3865.48	Rigidity	273.1mm centralizer	55	48
3865.48	4082.89	Casing without coupling cannot be added with centralizer

4) Cement injection

On May 24, 2015, 6:00-8:00 circulation;-11:30 cementing preparation;-16:45 cementing.

Construction process

Sequence	Construction time	Operation content	Workload m3	Density g/cm3	Displacement (m3/min)	Pressure MPa
1	11;20～11;30	Pipeline pressure test				25
2	11;30～12:00	Flushing Fluid Injection	25	1.0	1.5	9
3	12;00～13:09	water injection mud	95	1.90	1.5	10-0
4	13;09～13:10	Release stopper
5	13;10～13:15	Rubber press plug	4.0	1.0	1.0	0
6	13;15～14:52	Large pump for slurry replacement	188.68	1.75	1.9-2.3	0-22
7	14:52～15:20	Lower the sleeve, and the plug enters the connecting cylinder.
8	15:20～16:45	Flush the wellhead, set the casing head and check the backflow
9	16:45~27 6:00	Ring pressure, Hou Ning				10
Note: ① No rubber plug is installed and not pressed. ② When flushing the wellhead, lower the casing head hanger while flushing, first flush with water, then flush with air. ③ When the return cylinder is fully inserted and pressed for 20t, the remaining load acts on the casing head hanger.

5) Cementing quality:

From May 28 to 20:00, 2015, drill to the well depth of 3880m and probe into the cement plug (throttle float collar 4039.48m, cement plug height 159.48m); On May 30, the plug was swept to a well depth of 6177m to prepare for electric logging and cementing quality.

Cementing quality of electrical logging back-up section on May 31, 2015. Cementing quality is acceptable.

5. Summary of Three Opening and Cementing

1), scraping pipe to eliminate mud cake is conducive to improving the quality of interface bonding.

2), a sufficient amount of efficient flushing fluid to remove mud cake, improve the flow of very good.

3) Adhere to large displacement construction from beginning to end, which is conducive to improving the replacement efficiency.

5. four-opening 193.7mm casing suspension cementing

1. Basic information

1) Well structure (see front)

2) Slurry performance: (anti-sloughing slurry of polysulfonated potassium chloride)

Density (g/cm3)	Viscosity (s)	Initial/final cut (Pa)	Mud cake (mm)	Filtration loss (ml/30min)	Sand (%)	Chloride ion content (mg/l)
1.95	81	4/14	0.5	2.0	0.2	35855
YP(Pa)	PV(mPa.s)	coefficient of friction	PH	Φ600	Trillion 300
7.5	44	0.21	11	93	54

3) Formation breaking test

When the well depth is 7050m, the wellhead pressure is 20.1MPa, the mud density is 1.73g/cm3, and the formation is not broken, the equivalent density of the bottom hole is 2.02g/cm3.

4) Pump condition and drilling parameters

Pump No.	Model	Cylinder diameter mm	Displacement L/S	Pump pressure MPa
1	F1600	150	16	29.5
2	F1600	150	16	29.5

Note: Maximum drilling displacement: 32 L/S, maximum pump pressure: 29 MPa.

5) Complicated situations

There are three times of leakage in this opening, one in choke and kill cycle and two in normal drilling. The situation is as follows:

The first leakage occurred on July 30, 2015 at 9:43 when drilling to 7354.61m (well slurry density 1.73g/cm3) and found overflow in high-pressure water layer. The shut-in vertical pressure is 7.0MPa and the casing pressure is 8.0MPa, with an upward trend. At 10:35, the mud with density of 1.96g/cm3 was used to kill the well, and leakage occurred. Then the well was pressed and circulated with plugging mud, and it returned to normal at 0:00 on August 1. During the whole well killing process, 692 m3 of killing fluid with density of 1.95-2.00g/cm3 and 356 m3 of leakage were pumped.

The second leakage occurred when drilling to 7405.70m on August 6, 2015. It was analyzed as formation fractured leakage. At that time, the mud density was 1.95g/cm3. During the plugging process, the pumped density was 1.75 and 1.95 plugging slurry, totaling 50 m3, and the leakage plugging slurry was 28.26 m3. The total amount of leakage is 48.06 m3, and the loss time is 11.67h.

The third loss occurred on 28 August 2015 drilling to 7496.25m, when the mud density was 1.95g/cm3. It was found that the vertical pressure decreased and the outlet return slurry decreased to loss of return. Before and after the leak plugging for many times. It is judged that the leakage layer is 7120.0-7253.0m, which is a formation fracture type leakage. The cumulative leakage is 532.15 m3, and the loss time is 10.65d.

Judging from the above three leakage conditions, the leakage horizon is distributed between 7120m-7405m in the lower section.

6) Well diameter and well deviation data

According to the electrical logging results, the average well diameter is 250.5mm, the well diameter enlargement rate is 3.8, the maximum well deviation is 7.76 °/6423m, and the azimuth angle is 172.49 °.

7) Well temperature data

Regional annual average temperature (℃)	Well depth (vertical depth) m	Ground temperature gradient (℃/100m)	Static bottom hole temperature (℃)	Bottom hole circulating temperature (℃)
15	7699	2.0	168.98	135.18

Note: On October 8, the electric logging bottom hole temperature was 160 ℃ (36h at rest), and the cement slurry test temperature was 135 ℃.

8) Drilling tool structure

Φ241.3mmHF617HX cone bit 630*431 joint float valve Φ177mm drill collar × 3 411 × 4A10 joint Φ165mm drill collar × 15 4A11 × 410 joint Φ127mm weighted drill pipe × 1 bypass valve Φ127mm weighted drill pipe × 14 Φ127mm drill pipe × 70 411 × ZY540 joint Φ139.7mm drill pipe.

9) Comprehensive logging interpretation of gas reservoir

floor number	Well interval (m)	Thickness (m)	formation	Interpretation Conclusion	floor number	Well interval (m)	Thickness (m)	formation	Interpretation Conclusion
1	6920.0-6926.2	6.2	O3w	gas-bearing layer	9	7205.5-7206.9	1.4	∈2d	gas-bearing layer
2	6926.2-6927.9	1.7	O2b	crack layer	10	7233.5-7243.1	9.6	∈2d	Gas-bearing water layer
3	6964.3-6965.6	1.3	O1m	crack layer	11	7290.3-7295.3	5.0	∈1l	Gas-bearing water layer
4	6967.0-6970.3	3.3	O1m	gas-bearing layer	12	7300.2-7301.9	1.7	∈1l	crack layer
5	7006.0-7010.0	4.3	∈3x	Gas-bearing water layer	13	7302.5-7310.7	8.2	∈1l	Gas-bearing water layer
6	7030.2-7036.7	6.5	∈3x	Gas-bearing water layer	14	7317.9-7320.9	3.0	∈1l	Gas-bearing water layer
7	7129.7-7131.4	1.7	∈3x	Gas-bearing water layer	15	7335.0-7361.0	26.0	∈1l	Gas-bearing water layer
8	7136.9-7138.9	2.0	∈3x	Gas-bearing water layer

10), after-effect display

Serial Number	Date of measurement	Location of hydrocarbon reservoir (m)	up-channeling velocity (m/h)	Total hydrocarbon (%)	Mud parameters		Bubble
Serial Number	Date of measurement	Location of hydrocarbon reservoir (m)	up-channeling velocity (m/h)	Total hydrocarbon (%)	Density (g/cm3)	Viscosity (s)	occurrence	(%)
1	2015.6.18	6345.00-6346.00	4.84	0.22 ↑ 2.52	1.60	68	None
2	2015.6.27	6926.00-6928.50	5.88	0.42 ↑ 1.61	1.74 ↓ 1.73	79↑80	None
3	2015.8.4	7352.00-7354.61	23.85	0.05↑0.70	1.96 ↓ 1.95	70↑72	needle tip	1
4	2015.8.10	7352.00-7355.00	39.73	0.10 ↑ 9.60	1.92 ↓ 1.87	64↑70	needle tip	2
5	2015.8.13	7352.00-7355.00	12.24	0.05↑1.07	1.93	77	needle tip	1
6	2015.8.14/15	7352.00-7355.00	8.28	0.04↑1.40	1.93	98	None
7	2015.8.16	7352.00-7355.00	9.63	0.08 ↑ 0.14	1.93	70	None
8	2015.8.18/19	7352.00-7355.00	9.48	0.03 ↑ 0.85	1.95	90	None
9	2015.8.22/23	7352.00-7355.00	9.79	0.09↑1.39	1.94 ↓ 1.93	86↑90	None
10	2015.8.27	7352.00-7355.00	11.53	0.04↑0.86	1.95 ↓ 1.94	95↑99	None
11	2015.9.6	7352.00-7355.00	9.35	0.09↑0.67	1.94 ↓ 1.93	110 ↓ 100	None

2. Purpose and method of cementing

The method of liner bottom cementing and then back-connecting is adopted to seal and fix the open hole section and casing overlap section of the fourth spuds, so as to create conditions for revealing the target layer and safe drilling in the next spuds.

3. Main technical difficulties in cementing

The high-pressure gas and water layer is active, and well leakage occurs, there are multiple sets of pressure systems with different fluids, in addition to the depth of the well, the mud density is high, the composition is complex, the primary sealing section is long, the annular space gap is small, and the cementing construction has many difficulties and risks:

1), ring air water risk. There are gas layers and active high-pressure water layers in the lower well section. High formation pressure, high pressure water into the cement slurry seriously damage the overall performance of the cement slurry, and even cause cementing failure, pressure stability, to ensure the water layer and its adjacent well interval cementing quality, to prevent the ring air, water channeling is the main difficulty of this cementing.

2) Risk of lost circulation. Three times of leakage occurred in this spout drilling, one during overflow and killing and two during drilling, belonging to fracture type leakage. Leakage prevention in the process of casing running and cementing is the difficulty of this cementing.

3) It is difficult to improve the displacement efficiency of deep wells:

① The geomagnetic force of the deep formation is strong, and there is magnetic iron powder in the mud weighting agent. The mud cake formed by the mud on the well wall and casing wall is thick and stubborn, and it is not easy to be washed clean, which seriously affects the displacement efficiency and the quality of interface cementation;

② The maximum outer diameter of the hanger body is 240mm, the unilateral clearance is only 2.71mm, the casing is thickened at 206.4mm outside the lower 6830-7699m interval, the unilateral clearance is 22.05mm, the flow area is small, the pump pressure is high, the construction displacement is limited, and turbulent displacement cannot be realized, which is very unfavorable to improving the displacement efficiency.

③ The density of spacer fluid is consistent with that of mud, and the density difference between cement slurry and mud is 0.10g/cm3. Small density difference is not conducive to effective displacement.

④ Casing without coupling, centralizer cannot be installed, and bottom cementing, casing centering degree is poor, which affects displacement effect.

4) Difficulties in narrow pressure window:

In the same section of open hole, high-pressure gas, water layer and leakage layer coexist, the pressure window of cementing construction is narrow, and it is difficult to balance pressure stability and leakage prevention, which is the difficulty of cementing design and construction.

5), well depth, small clearance, casing difficult.

241.3mm borehole, 193.7mm casing running depth 7699m, a record in China, and casing coupling diameter 215.9mm, unilateral spacing is only 12.7mm, annular space gap is small, casing running friction resistance is large. The coexistence of high-pressure layer and low-pressure leakage layer, there is a risk of differential pressure sticking, to ensure the safe and smooth running of the casing in place is a difficult point in this cementing.

6), construction safety difficulties.

Deep well, long open hole (1496m), high circulating pump pressure, limited displacement, sand in the borehole is not easy to circulate clean, cement slurry is easy to block the pump when returning, especially at the hanger, affecting construction safety.

7), deep well high temperature cement slurry debugging difficult:

① The high-pressure brine layer of Longwangmiao Formation has high requirements for pressure stabilization, salt resistance and water resistance of cement slurry, and fixing the high-pressure brine layer is a major difficulty in this cementing cement slurry;

② High temperature in deep wells requires high temperature stability of cement slurry system and strict thickening time. At the same time, high temperature has a great influence on the strength development of cement stone. Therefore, the cement slurry is required to have good high temperature resistance in terms of stability, rheology, thickening time, strength development, etc., and it is difficult to debug the cement slurry.

③ The lower gas layer, especially the water layer is active, and the pressure coefficient is high, which requires the cement slurry to have good anti-channeling performance.

④ Deep well high temperature mud composition complex, high degree of salinity, cement slurry at high temperature migration section and migration time is long, the cement slurry anti-pollution ability put forward high requirements, to ensure the construction safety of cement slurry is a major difficulty.

⑤ It is the first time to predict the bottom hole temperature in this area, and there may be a large error in the determination of the cement slurry experimental temperature, and the cement slurry may be super-retarded.

4. Main technical measures

1) Hole preparation and casing running

① The logging provides detailed data of double well diameter, well deviation, azimuth, well temperature, oil, gas and water layer location, etc.

② After electrical logging, the well shall be opened carefully, and three centralizers shall be added successively to strengthen the structure of the drilling tool. The drilling tool shall be equipped with three under-sized centralizers (three drill collars above the bit, one centralizer for each drill collar, and the outer diameter of the lowest centralizer shall not be less than 238mm) in the last pass to ensure that the rigidity of the drilling tool is greater than the casing string.

③ The well shall be connected thoroughly. The well shall be connected and ream repeatedly for the trip blocking section, the reduced diameter section and the well section with large borehole curvature change, and short trip inspection shall be conducted to ensure the smooth running of the casing; if it is not possible to confirm whether the drilling tool is suitable, the casing shall be used to simulate the successful running of the casing with 1 column of the most rigid casing before the formal running. If there is a problem in simulated casing running, continue to use more rigid drilling tools to open the well, and the casing running operation will not be carried out until the simulated casing running is successful.

④ After the circulation through the well to the bottom is normal, large displacement (not less than the maximum drilling displacement) circulation shall be carried out for at least two weeks to treat the mud until the mud performance of the inlet and outlet is the same. Under the condition of ensuring the stability of the borehole wall, the mud performance shall be adjusted as much as possible to reduce the friction resistance and improve the fluidity of the mud. To ensure that the casing smoothly to the design position.

⑤ Short tripping shall be carried out after the last pass through the well to the bottom, and solid lubricant and high temperature resistant material sealing fluid shall be injected into the complex well section after smooth tripping.

⑥ The casing runs down to the upper casing shoe for one late time.

⑦ When the liner hanger goes into the well, it is forbidden to bite the body with tongs to prevent damage to the matching clearance of internal parts and avoid accidents such as tool failure. The instructions for use shall be followed.

⑧ After the casing is run, the small displacement is jacked to prevent high pump pressure from leaking the formation. After normal operation, the displacement is gradually increased until the large displacement is fully circulated and washed, the bottom of the well is thoroughly cleaned, and the mud performance reaches the density balance of inlet and outlet. Before cementing, the density is 1.95g/cm3, the mud viscosity is ≤ 65s, and the initial cut is ≤ 6pa.

⑨ Before cementing, the water channeling velocity of oil and gas is less than 10 m/h, and the density difference between inlet and outlet is less than 0.02g/cm3.

2) Technical measures to improve displacement efficiency

① Reasonably design centralizers, one for every 3 casings in the overlapping section and one rigid swirl centralizers for every casing in the open hole section, so as to improve the centralization of the casing and change the flow pattern by using the swirl effect to improve the displacement efficiency.

② After running casing circulation is sufficient, use 20m3 fiber mud to carry sand for one week to clean the borehole.

③ The preflush combination system of pilot slurry, high-efficiency flushing fluid and high-suspension spacer fluid shall be adopted to effectively flush the cementing interface and isolate the slurry and cement slurry, and the contact time of each slurry shall not be less than 7 minutes to improve the displacement efficiency.

④ Pilot slurry, density 1.95g/cm3, viscosity ≤ 60s, initial shear ≤ 6Pa, dynamic shear force ≤ 12Pa.

⑤ Adjust the performance of flushing fluid to realize turbulent flow or effective laminar flow displacement when the displacement is 1.0-1.2 m3/min, thus improving the displacement efficiency.

⑥ Under the premise of maintaining no leakage underground, keep large displacement construction. Make the annulus return speed reach at least 1 m/s to improve the displacement efficiency.

3) Anti-channeling technical measures

① Effectively press and stabilize the gas layer, the density difference between the inlet and outlet of mud is <0.02g/cm3, the upward channeling speed of oil and gas is <10 m/h, and the total hydrocarbon of gas logging value is <5%.

② Effectively press the stable water layer, the density difference between the inlet and outlet of mud is less than 0.02g/cm3, the upward channeling speed of brine is less than 2 m/h, and the mud filtrate Cl-<40000mg/l (under normal conditions, the chloride ion content of mud is 35855mg/l).

③ Adopt the whole process balance cementing, design the reasonable slurry column structure and two coagulation interfaces, optimize the construction pump pressure and displacement, accurately calculate the back pressure value and formulate the pressurization measures. Before cementing, during cementing and during the period of waiting for setting, gas and water should be laminated stably, the gas and oil channeling speed should be less than 10 m/s, and the density difference between inlet and outlet of mud should be less than 0.02g/cm3. The specific anti-channeling measures include cement slurry and double coagulation interface design, pressure stability calculation, back pressure measures, waiting coagulation design, etc.

4) Leak-proof technical measures:

① Formation pressure requirements: do formation dynamic pressure test, with 2.10g/cm3 of 60m3 heavy slurry, according to the displacement of 28L/S into the well circulation for two weeks, no leakage is qualified.

If leakage occurs in the process of formation pressure density increase: if the formation pressure capacity cannot meet the designed slurry density requirements, the slurry column structure and slurry density and corresponding measures shall be adjusted according to the actual pressure capacity on the premise of meeting the pressure stabilizing gas and water layer; if the formation pressure capacity is far from meeting the designed slurry density requirements, the leakage shall be stopped first to improve the formation pressure capacity in order to ensure the cementing quality, then modify the cementing construction design or adjust the cement slurry density and other measures according to the actual bearing capacity of the formation.

If the leakage and overflow pressure window of the formation is very narrow, the slurry density shall be selected within the narrow window. The slurry density shall not be greater than the leakage density and not less than the pressure stability density. At the same time, the slurry consistency advantage shall be used for cementing construction.

If serious leakage occurs before running the casing, the leakage interval shall be blocked first to improve the pressure bearing capacity of the formation, and then the casing shall be run for cementing to ensure that leakage does not occur during cementing.

If serious leakage occurs during cementing, remedial measures shall be taken as soon as possible or a positive injection and reverse extrusion cementing scheme shall be adopted. When the positive injection and reverse extrusion cementing scheme is adopted, attention shall be paid to leaving a channel for cement slurry extrusion and preventing well control risks.

② Adjust the mud performance, minimize the viscous shear performance of the mud, and strive to return the cement slurry to the design position.

③ When running casing, strictly control the lowering speed of casing and drilling tools. The lowering time of each casing shall not be less than 45s, and the lowering time of each column of drilling tools shall not be less than 2 minutes to prevent excessive exciting pressure in the well. Special personnel shall be assigned to observe the slurry return situation, check the discharge volume, and deal with any abnormality in time.

④ After the casing is lowered to the bottom, the displacement of the pump is from small to large, and gradually raised to the design displacement after the pump pressure is normal.

⑤ Selection of slurry density: the density of the weighted spacer fluid shall be consistent with that of the mud, the density of the cement slurry collar and tail slurry shall be 2.05g/cm3, and the equivalent density of the annular liquid column after cementing shall be 1.97g/cm3, which is only increased by 0.02g/cm3, which is conducive to leakage prevention.

⑥ Add 0.2% plugging fiber with a length of 3~5mm into the weighted spacer and cement slurry to increase the plugging effect.

⑦ Optimize the construction displacement, adopt the variable displacement construction method, and control the construction displacement not higher than the circulating displacement.

5) Ensure construction safety measures

① All drill pipes, delivery tools (including nipples), casing and hanger shall be of standard drift diameter gauge (300mm × Φ75mm, 300mm × Φ65mm), and attention shall be paid to safety. It is strictly forbidden to fall into the well. The inner diameter and chamfer of drill pipe conversion joint shall meet the requirements for safe passage of rubber plug. Do strength check and flaw detection for well-entering pipe string.

② Weigh the drilling tools during well opening to provide basis for hand loss.

③ After the casing is running to the design well depth, control the pressure within 5MPa and circulate with a small displacement. After sufficient circulation, increase the displacement to avoid formation leakage.

④ Before cementing construction, the pressure test of 35MPa of construction equipment is qualified, and a set of standby high-pressure pipeline is reserved.

6). Measures for adding back pressure

Same as before. This section is omitted.

7) Other technical measures

① In order to ensure the sealing quality of the overlapping section, the tail pipe and the upper casing overlap 200m for the overlapping section, and the plug 77m is left to ensure the sealing quality of the casing shoe. In order to ensure the sealing quality of bell mouth, 150m of cement shall be reserved.

② In order to ensure the accuracy of the slurry displacement, the drilling team shall provide accurate measurement of the internal volume of the drilling tools. The displacement metering is subject to the metering of the mud tank of the drilling team, supplemented by logging pump flushing and cementing flowmeter metering.

③ Three-party testing is required for cement slurry test, and casing running and cementing can only be carried out after all requirements are met.

5. Cement slurry

1) Cement slurry technology

① Optimum cement slurry system, using double coagulation single density, double coagulation interface 6800m. The collar and tail slurry are all made of latex weighted cement slurry system, and the density of the collar and tail slurry is 2.05g/cm3.

The latex cement slurry has low water loss, the lead slurry has micro-expansion performance, the free water is zero or close to zero, and the water loss is within 50ml; the tail slurry latex cement slurry has good anti-gas and water channeling function, zero free water, and the water loss is within 50ml.

③ In order to ensure that the tail slurry is sealed in time, the thickening time of the tail slurry is longer than the construction time and not more than one hour. The thickening curves of the lead slurry and tail slurry shall be thickened at right angles, and the transition time shall not exceed 10 minutes. For the lead slurry 2.05g/cm3, tail slurry 2.15g/cm3 density divergence thickening experiment. Make the temperature divergence and thickening test of cement slurry at 130 ℃ for lead slurry and 140 ℃ for tail slurry.

④ The slurry has high settlement stability, and the density difference between upper and lower is less than 0.02g/cm3 after standing for 2h. The fluidity of the slurry is good. Not only the fluidity at high temperature is good, but also the fluidity at low temperature can be convenient for construction.

⑤ Adopt Jiahua G-grade cement with stability and good compatibility with admixtures;

⑥ Adopt functional admixture to control slurry performance and improve anti-channeling ability of slurry and cement stone

⑦ To ensure that the cement slurry has high early strength and high temperature strength stability, through the reasonable selection of silicon calcium ratio, to achieve high temperature conditions curing cement stone strength greater than 14MPa.

⑧ Adopt functional admixture to improve the leakage prevention ability of cement slurry

⑨ Reasonable adjustment of cement slurry fluid performance, and the use of functional front fluid to improve displacement efficiency

⑩ Make pre-contamination experiments with different mixing ratios of pilot slurry, spacer fluid, mud cake curing agent and lead slurry. The post-contamination experiment of different mixing ratios of tail slurry, pressure plug fluid and displacement slurry shall be carried out.

2) Test conditions of cement slurry

The temperature is 135 ℃, the pressure is 145MPa, and the heating and boosting time is 60min. Measure the thickening time under constant temperature and pressure.

3) Cement slurry formula:

Lead slurry: Jiahua Grade G Cement + GW-1(40%)+ BS500(3%)+ BS600(1%)+ BS300(1%)+ JZ-II(44%)+ BS100L-G(4%)+ BS200-G(7%)+ JR(12%)+ BP-1A(0.6)

Wet Blend/Dry Blend: 0.32; Dry Blend Pulping Rate: 0.62

Tail slurry: Jiahua Grade G Cement + GW-1(40%)+ BS500(3%)+ BS600(1%)+ BS300(1%)+ JZ-II(44%)+ BS100L-G(4%)+ BS200-G(5%)+ JR(12%)+ BP-1A(0.6)

Wet Blend/Dry Blend: 0.32; Dry Blend Pulping Rate: 0.62

4) Cement slurry performance

Project	latex collar slurry		latex tail slurry
Project	Design	Actual	Design	Actual
Density (g/cm3)	2.05	2.05	2.05	2.05
Water loss (ml)	≤50	44	≤50	24
Free liquid (%)	0	0	0	0
72h(167 ℃) compressive strength (MPa)	-	-	≥14	21.2
72h(135 ℃) top compressive strength (MPa)	≥14	18.6	-	-
Initial consistency (Bc)	≤20	20	≤20	19
100Bc thickening time (min)	400-460	438	180-240	225
Density high point (2.08g/cm3) time (min)	360-400	473 (shutdown)	160-220	183
Temperature high point (140 ℃) time (min)	360-400	361	160-220	-
Temperature high point (145 ℃) time (min)	-	-	-	145
Flow degree (cm)	≥ 20	21	≥ 20	21
Sedimentation stability (stationary for 2 hours) Density difference between upper and lower g/cm3	≤ 0.02	0.02	≤ 0.02,	0

5),Rheological data of cement slurry

Name	Φ600	Trillion 300	Φ200	Φ100	Φ6	Φ3
Collar	282	160	116	63	8	6
tail slurry	235	130	94	55	9	6

6）Pollution experiment

Pilot slurry	barrier fluid	Flushing fluid	Collar	tail slurry	Mud	Thickening time (min)
10%	10%	20%	60%			420min not thick
25%	25%	25%	25%			400min not thick
10%	20%		70%			400min not thick
33%	33%		33%			400min not thick
				70%	30%	212min thick

6. Casing running

Casing will be started at 23:30 on October 10, 2015, completed at 2:00 on October 12, and then transported by drilling tools. At 19:00 on October 13, drilling tools will transport liner to the bottom of the well to circulate mud. From 6:00 to 7:00 on October 14, 20m3 fiber mud was pumped into the borehole to purify the borehole. -8:00 hanger is released (casing is lowered to a well depth of 7699m and is connected to a top of 5985.79m. 7:10 Turn forward for 5 laps to release the torque and reverse for 1 laps, then turn forward for 11 laps to release the torque and reverse for 1 laps, then turn forward for 15 laps to release the torque and reverse for half a laps. The lifting weight of 1m is 190T, and the handle is successful);-9:30 Cementing preparation;

1) Pipe string structure (bottom-up)

Pipe string name	Size (mm)× steel grade × wall thickness (mm)× buckle type	Lower depth (m)
Return cylinder		5986.99
Hanger	F193.7mm×TP110TSS×TP-CQ	5990.34
Casing	Ф 193.7mm × TP110TSS mm × 12.7mm × TP-CQ mm × 79	6828.51
Variable buckle short	Ф 193.7mm × TP-CQ to Ф 206.4mm × TP-FJ	6830.01
Casing	Ф 206.4mm × TP110TSS mm × 19.05mm × TP-FJ mm × 75 pieces	7620.27
Ball Seat	Ф206.4mm×TP110TSS×19.05mm×TP-FJ	7620.62
Casing	Ф 206.4mm × TP110TSS mm × 19.05mm × TP-FJ mm × 1 root	7631.74
Float collar 2	Ф206.4mm×TP110TSS×19.05mm×TP-FJ	7631.99
Casing	Ф 206.4mm × TP110TSS mm × 19.05mm × TP-FJ mm × 3 pieces	7665.01
Float collar 1	Ф206.4mm×TP110TSS×19.05mm×TP-FJ	7665.26
Casing	Ф 206.4mm × TP110TSS mm × 19.05mm × TP-FJ mm × 3 pieces	7697.97
extended float shoes	Ф206.4mm×TP110TSS×19.05mm×TP-FJ	7699.0

Note:(1) The cement plug in the pipe is 77m;2), this layer and upper layerCasing Performance Data Sheet

Outer diameter mm	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Outer diameter of coupling mm	Tensile strength kN	Extrusion strength MPa	Internal pressure strength MPa
193.7	TP110TSS	12.7	TP-CQ	58.09	215.9	5477	80.70	87.03
206.4	TP110TSS	19.05	TP-FJ	87.97	206.4	4507	133.28	98.04
206.4	TP110TSS	19.05	TP-NF	89.97	215.9	5868	133.28	122.55
282.6	TP110TSS	17.32	TP-NF	115.80	293.50	7825	76.0	77.40
284.2	TP110TSS	18.12	TP-FJ	118.99	284.2	6089	80.40	67.72
273.1	TP110TSS	13.93	TP-CQ	91.50	293.45	7705	53.37	67.66
273.1	TP110TSS	13.93	TP-NF	91.44	283.00	6173	53.37	67.66

3), drill pipe performance data table:

Outer diameter mm	Steel Grade	Inner diameter mm	Drill pipe joint mm	Extrusion strength MPa	Internal pressure strength MPa	Tensile strength t
139.7	G105	118.6	184.2	96.5	95.6	316.24
127	G105	108.6	177.8	89.6	91.7	251.61

4), strength check:

Outer diameter mm	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Section weight t	Tired weight t	Safety factor
Outer diameter mm	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Section weight t	Tired weight t	Tensile	Anti-extrusion	Resistance to internal pressure
193.7	5990～6830	840	TP110TSS	12.7	TP-CQ	58.09	48.80	125.25	3.37	1.03	2.13
206.4	6830～7699	869	TP110TSS	19.05	TP- FJ	87.97	76.45	76.45	4.39	1.45	2.98

Note:(1) Hanging first and then connecting back to cementing. The casing strength calculation is based on the Structure and Strength Design of Casing String (SY/T 5724-2008).

5) Strength check of drilling tools fed into liner:

Outer diameter of tail pipe mm	drill pipe	Floating weight of drill pipe and liner (t)	Tension allowance t	Tensile safety factor
F193.7	Φ139.7mmG105 (wall thickness 10.54mm)* 2500m	236.81	79.46	1.33
F193.7	Ф 127mm G105 (wall thickness 9.19mm)* 3485m	167.67	83.93	1.50

61). Placement position of centralizer

well interval	From	To	Centralizer type	Centralizer specification mm * mm	Placement spacing (m)	Placement quantity (only)
Overlapping Segments	5990m	6203m	swirl rigidity	193.7*228	33	6
Open eye section	6203m	6830m	swirl rigidity	193.7*228	11	54
Open eye section	6830m	7699m	Without coupling sleeve, centralizer cannot be installed.

7. Cement injection and cementing construction

Cementing is ready at 9:30 on October 14, 2015.-Cementing construction at 14:30;-16:00 Trip-out of 15 columns (up to 5560.4m in depth);-18:00 Cyclic discharge of mixed slurry; -5 columns short at 18:30 (up to 5415.79m in depth);-6:00 pressure holding 12MPa waiting for coagulation.

1) Cement injection construction record

Sequence	Construction time (min)	Operation content	Workload (m3)	Density (g/cm3)	Displacement (m3/min)	Pressure (MPa)
1	14th 9:30~9:47	Manifold pressure test				35
2	9:47～10:27	Injection of pilot slurry	30	1.95	1.0	11
3	10:45～11:08	Injection of barrier fluid	15	1.95	1.0	11
4	11:08～11:12	Flushing Fluid Injection	3	1.02	1.0	14
5	11:22～12:25	Injection of collar latex	25	2.05	1.0	14
6	12:25～12:48	Injection tail slurry latex	18	2.05	1.0	14
7	12:48～12:50	Release the drill pipe rubber plug
8	12:50～12:52	Replacing the plug fluid	2	1.95	1.0	14
9	12:52～13:27	replace the mud	33	1.95	1.2-1.0	8～10
10	13:27～13:31	Roof protection fluid	2.5	1.95	0.8	16
11	13:32～14:25	replace the original mud	56.85	1.95	1.0	16-20
12	14:25～14:30	Touch pressure, check backflow	2.0	1.95	0.5	25-28
13	14:30～14:40	Unloading cement head
14	14:40～16:00	tripping out and continuous grouting	15 Pillar
15	16:00～18:00	Cycle 1 week	182	1.95	1.8	10
16	18:00～18:30	tripping out	5 Pillars
17	18:30~17 16:00	Well shut-in, pressure suppression and waiting for coagulation				12

2) Cementing quality:

At 21:00 on October 18, 2015, the upper plug surface was drilled to 5722m (the upper plug height was 263.79m).

At 9:00 on October 22, 2015, the lower plug surface was 7605m (the lower plug height was 15.27m).

On October 24, 2015, from 5:00 to 16:00, the sound amplitude was measured electrically (measuring section: 5987-7615m). Cementing quality is acceptable.

8. Summary of Fourth Opening Suspension Cementing

1) In order to ensure the smooth running of casing, the well-passage measures shall be formulated and strictly implemented for the small clearance borehole of deep well.

2) The deep well high temperature cement slurry system is properly selected, the performance adjustment is reasonable, and the deep well high temperature construction is safe.

3), the suspension cementing quality is qualified, but not high quality, the main reasons are:

① The salt water layer is active, which affects the sound amplitude.

② The amount of flushing fluid is too small, and the interface flushing effect is not good, which affects the quality of interface cementation.

③ The displacement of slurry displacement during construction is generally low, and the displacement efficiency is not high.

7. 5 146.1mm liner suspension cementing

1. Basic information

1) Well structure (see front)

2) Mud performance

Density (g/cm3)	Viscosity (s)	Initial/final cut (Pa)	Mud cake (mm)	Filtration loss (ml/30min)	Sand (%)
1.43	67	2/5	0.5	2.5	0.2
YP(Pa)	PV(mPa.s)	coefficient of friction	PH	Φ600	Trillion 300
2.5	38	0.081	11	81	43

3) Formation fracture pressure test

The well depth is 7714.63 m, the mud density is 1.62g/cm3, the wellhead pressure is 25MPa, the formation is not broken, and the equivalent density is 1.95g/cm3.

4) Pump condition and drilling parameters

Pump No.	Model	Cylinder diameter mm	Displacement L/S	Pump pressure MPa
1	F1600	150	15	16
2	F1600	150	15	16

Note: maximum drilling displacement: 15L/S, maximum pump pressure: 26MPa.

5) Well diameter and well deviation

According to the electrical logging well diameter, the average well diameter is 173.63mm and the well diameter enlargement rate is 5.17%. The maximum well deviation is 5.62 ° (well depth is 8365m, azimuth angle is 297.85 °).

6) Well temperature data

Regional annual average temperature (℃)	Well depth (vertical depth m)	Ground temperature gradient (℃/100m)	Static bottom hole temperature (℃)	Bottom hole circulating temperature (℃)
15	8418	1.904	175.1	157.5

Remarks: the test temperature of cement slurry shall be 160 ℃. Static temperature at bottom of electric logging hole is 175 ℃ (static for 48h).

7) Complicated situations

① When drilling 8053.47m, Party A requires coring, and then short trip is carried out immediately. After short trip, well leakage occurs when circulating oil and gas channeling speed is measured. At this time, the mud density is 1.59g/cm3, and the total amount of lost circulation is 7.8 m3.

② Main oil, gas and water layer display

horizon	Well interval m	lithology	Total hydrocarbon%	Mud parameters		Groove surface display	On-site explanation
				Density g/cm3	Viscosity s
Z2dy4	8108.50-8112.00	Grey siliceous and siliceous dolomite	0.08 ↑ 0.67	1.45	60	None	gas-bearing layer

Note: The gas-bearing layer of the fourth section of the Dengying Group is 3.5m/1 layer.

③ After-effect display

Serial Number	horizon	Location of hydrocarbon reservoir (m)	Gas channeling velocity (m/h)	Total hydrocarbon (%)	Mud parameters		Bubble
Serial Number	horizon	Location of hydrocarbon reservoir (m)	Gas channeling velocity (m/h)	Total hydrocarbon (%)	Density (g/cm3)	Viscosity (s)	occurrence	(%)
1	Z2dy4	8108.50-8112.00	45.74	0.04↑5.57	1.43 ↓ 1.42	70 ↑ 74	needle tip	1
2	Z2dy4	8108.50-8112.00	27.79	0.08↑7.78	1.44 ↓ 1.43	59 ↑ 62	needle tip	1
3	Z2dy4	8108.50-8112.00	26.77	0.10↑6.93	1.44 ↓ 1.43	61↑64	needle tip	1
4	Z2dy4	8108.50-8112.00	25.61	0.08↑8.64	1.44 ↓ 1.43	72↑75	needle tip	1
5	Z2dy4	8108.50-8112.00	27.97	0.09↑11.06	1.44 ↓ 1.43	68↑72	needle tip	2
6	Z2dy4	8108.50-8112.00	29.21	0.13 ↑ 5.73	1.43 ↓ 1.42	101↑110	needle tip	1
7	Z2dy4	8108.50-8112.00	9.85	0.10 ↑ 9.41	1.45 ↓ 1.44	101 ↑ 108	needle tip	1

8) Drilling tool structure

① Cone drilling: Φ165.1mm cone bit float valve Φ120.6mm drill collar × 1 Φ160mm centralizer Φ120.6mm drill collar × 8 bypass valves Φ88.9mm weighted drill pipe × 17 311 × ZY390 joint Φ101.6mm drill pipe × 473 ZY391 × ZY540 joint Φ139.7mm drill pipe.

② PDC drilling: Φ165.1mmPDC drill bit single straight screw arrow check valve Φ160mm centralizer Φ120.6mm drill collars × 6 bypass valves Φ88.9mm weighted drill rods × 17 311 × ZY390 joints Φ101.6mm drill rods × 473 ZY391 × ZY540 joints Φ139.7mm drill rods.

③ Core drilling: Φ165.1mmPC327 core drill bit Sichuan 5-4 core barrel double male float valve Φ160mm centralizer Φ120.6mm drill collars × 6 bypass valves Φ88.9mm heavy drill pipes × 16 311 × ZY390 joints Φ101.6mm drill pipes × 473 ZY391 × ZY540 joints Φ139.7mm drill pipes.

2. Purpose and method of cementing

The liner suspension cementing method is adopted to seal and fix the open hole section and casing overlap section of the fifth opening hole section to create conditions for the next operation. Dezhou continental shelf 7 5/8 "× 5 3/4" XGJ-A mechanical liner hanger is selected.

3. Analysis of cementing difficulties and technical measures

1) Deep well and high temperature:

The expected quiescent temperature is 175°C. Deep wells and high temperature affect the strength development, settlement stability, rheology and other properties of cement slurry, and affect the sealing of the hanger.

Targeted technical measures:

① Adopt mechanical tailpipe hanger, and the hanger, ball seat, float collar, float shoe, etc. adopt rubber with temperature resistance above 200 ℃;

② Use a latex anti-gas channeling cement slurry system with double coagulation single density and high temperature resistance of 200 ℃, with a double coagulation interface of 7900m (200m above the gas layer) and a cement slurry density of 1.90g/cm3. The cement slurry shall have anti-gas channeling capacity coefficient <3, water loss ≤ 50ml and high settlement stability.

③ In order to ensure the strength development under high temperature, add sand to cement slurry to enhance its high temperature strength stability, and do a good job of 7d, 14d, 21d, 28d maintenance strength development experiment.

④ Use Jiahua Class G cement with good stability and good compatibility with admixtures, and reserve cement with sufficient aging time and stable performance in advance for cement slurry experiment and construction.

⑤ Do a good job of cement slurry performance and pollution test to ensure construction safety.

⑥ The performance of cement admixture and small and large sample cement slurry shall be monitored and rechecked throughout the process to ensure the stable performance of cement slurry before cementing and meet the construction requirements.

2), improve the displacement efficiency:

The annular space gap is small, the theoretical value of unilateral clearance in the open hole annular space is only 9.5mm, and the unilateral clearance at the tail pipe hanger tie-back barrel is only 5.15mm. In addition, the deep well has large circulating pressure consumption and limited construction displacement, making it difficult to realize turbulent flow replacement. At the same time, the liner is casing without coupling, so centralizer cannot be added and the casing is difficult to center.

Targeted technical measures:

① The spacer with flushing function and high settlement stability is used, with a density of 1.55g/cm3, which has a certain density difference with mud and cement slurry. 20m3 spacer fluid is used, and sand is added to the spacer fluid to strengthen the scouring and isolation effect.

② Before construction, 30m3 of pilot mud with excellent performance, density of 1.43g/cm3, initial cutting ≤ 6Pa, dynamic cutting force ≤ 12Pa, calcium resistance and cooling shall be injected to improve displacement efficiency and reduce wellbore temperature.

③The viscosity of each liquid in the slurry column is reasonably adjusted, so that the viscosity relationship between the three is: cement slurry> spacer> mud, and the displacement efficiency is improved by the viscosity difference.

④ Use the Ф 146.1mm casing stump to increase the centering degree of unjointed casing and seal the gas interval.

⑤ Before water injection, the slurry shall be fully circulated to ensure that there is no sand sedimentation in the borehole, and the slurry performance shall reach the density balance between inlet and outlet. Before cementing, the slurry density shall be 1.43g/cm3, the viscosity shall be ≤ 65s, and the initial cut shall be ≤ 6Pa.

3). Anti-channeling:

There are gas reservoirs in the well at 8108.5 m-8112.0m, and the prevention of gas channeling in cementing is the focus of this cementing.

Targeted technical measures:

Using balanced cementing technology, gas pressure should be stabilized during the whole construction process and waiting for setting. Therefore, first of all, reasonable liquid injection structure should be designed to ensure stable pressure under dynamic and static conditions of cementing. Secondly, back pressure should be added. In addition, the use of good anti-channeling performance of latex cement slurry, anti-channeling capacity coefficient SPN value is less than 3.

4) Leak-proof:

Leakage occurred during the sputum drilling process. Now the mud density is 1.43g/cm3 and the cement slurry density is 1.90g/cm3. The injection pressure of annulus fluid in the later stage of cementing is increased by about 5MPa, and the equivalent density of bottom hole is 1.50g/cm3. Well leakage may occur in the later stage of cementing, so preventing leakage is also one of the key points of cementing.

Targeted technical measures:

① To ensure sufficient bearing capacity of the stratum, conduct the dynamic bearing test of the stratum or simulate the bearing test of water injection slurry to meet the design requirements before the next step of construction. Simulated cement injection pressure-bearing test method: 35m3 of mud with a density of 1.90g/cm3 is used and circulated for two weeks with a displacement of 15L/s, and the downhole leakage is regarded as qualified.

When running casing, strictly control the lowering speed of casing and drilling tools. After entering the open hole section, the lowering time of each casing shall not be less than 45s, and the lowering time of each column shall not be less than 3 minutes, so as to prevent excessive exciting pressure in the well. Special personnel shall be assigned to observe the slurry return situation, check the discharge volume, and report any abnormality in time.

③ After the casing is lowered to the bottom, the pump displacement is gradually raised to the design displacement from small to large.

④ The density of spacer fluid (1.55g/cm3) is slightly higher than the density of mud. At the same time, 4m3 flushing fluid (density 1.02g/cm3) is used to reduce the injection pressure of annulus fluid, which is conducive to leakage prevention.

5) Hole preparation measures:

① The logging provides detailed data of double well diameter, well deviation, azimuth, well temperature, oil, gas and water layer location, etc.

② Three drilling tools shall be used to carefully open the well and circulate mud with large displacement (15L/s) after the well is opened to the bottom.

③ Short tripping shall be carried out after the last pass through the well to the bottom, and the sealing fluid shall be drilled into the open hole section before running the casing.

④ Before running casing and cementing, it is strictly required that the water channeling speed of oil and gas shall be less than 10 m/h and the density difference between inlet and outlet shall be less than 0.02g/cm3.

6) Technical measures for casing running (same as previous measures)

7) Measures to ensure construction safety:

① The drill pipe and tools (including nipples), casing and hanger shall be subject to standard drift diameter gauge, and the inner diameter and chamfer of the drill pipe adapter shall meet the requirements for safe passage of rubber plugs; the strength check and flaw detection inspection shall be done for the string of pipes entering the well.

② Weigh the drilling tools during well opening to provide basis for hand loss.

③ After the casing is in place, start the pump with a small displacement (the pressure is controlled within 5MPa) for circulation, and gradually increase the displacement after the circulation is sufficient to avoid leakage of the formation.

④ Before cement injection, the pressure test of construction equipment is 35MPa, and a set of standby high-pressure pipeline is reserved.

⑤ The calculated pump pressure is 20MPa, the maximum displacement pressure is 23.6MPa, the collision pressure is increased by 3-5MPa, and the estimated construction pressure is 28MPa.

8), Hou Ning measures

① After the completion of cementing, pull out 10 columns, keep continuous grouting during the tripping out, open the pump to clean the well in circulation after tripping out, move the drilling tool in the circulation process, after the circulation is clean, lift another 5 columns, close the sealer, and gradually add back pressure to 8MPa (the pressure holding value is appropriately adjusted according to the construction slurry density) for coagulation. Specific reference to the front to add back pressure measures.

② During the process of waiting for coagulation, special personnel shall be assigned to observe the wellhead pressure. If the pressure rises, if the rising value exceeds 40%(30MPa) of the bearing capacity of the casing and wellhead, the well killing measures shall be taken immediately and the relevant situation shall be reported to Party A in time.

③ Do a good job of field cement slurry sample strength maintenance test, strength to meet the design requirements, timely report to Party A.

④ The setting time shall be at least 72 hours, and the specific time shall be notified by Party A.

9) Other technical measures

① In order to ensure the sealing quality of the open hole section, the tail pipe and the upper casing overlap by 300m. In order to ensure the sealing quality at the bell mouth, a plug of 200m is reserved, and a plug of 80m is reserved to ensure the sealing quality at the casing shoe.

③ Three-party testing is required for cement slurry test, and casing running and cementing can only be carried out after all requirements are met.

4. Cement slurry

1) Test conditions of cement slurry:

The temperature is 160 ℃, the pressure is 135MPa, and the heating and boosting time is 90min. Measure the thickening time under constant temperature and pressure.

2) Cement slurry formula:

Lead slurry: Jiahua G + GW-1(40%)+ BS600(1%)+ BS100(0.8) + WD-4(1%)+ BS100L-G(8%)+ JR

　　(12%)+BS200-G(5%)+BS200R(1%)+BP-1B(1%)+BS300-J(2%)+WD-2(1%)

Wet Blend/Dry Blend: 0.43; Dry Blend Pulping Rate: 0.74

Tail slurry: Jiahua Grade G + GW-1(40%)+ BS600(1%)+ BS100(0.8) + WD-4(1%)+ BS100L-G(8%)+ JR

　　(12%)+BS200-G(4%)+BS200R(1%)+BP-1B(1%)+BS300-J(2%)+WD-2(1%)

Wet Blend/Dry Blend: 0.43; Dry Blend Pulping Rate: 0.74

3) Cement slurry performance

Project	Collar		tail slurry
Project	Design	Actual	Design	Actual
Density (g/cm3)	1.90	1.90	1.90	1.90
Water loss (ml/6.9MPa × 30min)	≤50	46	≤50	48
72 hours compressive strength (180 ℃× 21MPa)	-	-	≥14	18.9
Top compressive strength at 72 hours (155 ℃× 21MPa)	≥14	16.5	-	-
Initial consistency (Bc)	≤20	16	≤20	12
Thickening time (min)	440-470	562	190-220	226
Density high point (1.93g/cm3) thickening time (min)	400-430	446	160-190	191
High temperature point (165 ℃)	400-430	454	160-190	187
Flow degree (cm)	≥ 20	21	≥ 20	21
Free liquid (%)	0	0	0	0
Settlement stability, density difference between upper and lower 2 hours at rest ≤	0.02	0	0.02	0

　　4),Rheological data of cement slurry

Name	Condition	Φ600	Trillion 300	Φ200	Φ100	Φ6	Φ3
Collar	Normal temperature	>300	205	146	85	9	6
Collar	160℃	>300	180	130	75	8	6
tail slurry	Normal temperature	>300	227	152	89	10	8
tail slurry	160℃	>300	196	135	77	9	6

　　5）Pollution experiment

Cement collar slurry	50%	70%	70%	1/3	/
barrier fluid	50%	20%	10%	1/3	50%
Mud	/	10%	20%	1/3	50%
thickening time	>430min	>430min	>430min	>430min	>430min

5. Casing running

The liner will be run at 0:00 on February 5, 2016, the liner will be run at 8:00 on February 7, and the drilling tools will be run. At 4:30 on February 9, the drilling tools will transport the liner to a well depth of 8414m (without bottoming). Start the pump for circulation, lower the drilling tool to the bottom of the well at 8418m at 10:30, and the hanger is successfully released.

1) Pipe string design

Pipe string name	Size (mm)× steel grade × wall thickness (mm)× buckle type	Lower depth (m)
Return cylinder	Ф146.1mm×TP125S×12.34×TP-FJ	7483.12
Hanger	Ф 146.1mm × Ф 193.7mm (continental shelf)	7485.11
Casing	Ф146.1mm×TP125S×12.34×TP-FJ	7931.39
Transition Section	F146.1mm × F139.7mm	7933.47
Casing	F139.7mm x SM2550 x 10.16×VOM-TOP	8149.51
Transition Section	F139.7mm × F146.1mm	8150.82
Casing	Ф146.1mm×TP125S×12.34×TP-FJ	8355.02
Ball Seat	Ф146.1mm×TP125S×12.34×TP-FJ	8356.17
Casing	Ф146.1mm×TP125S×12.34×TP-FJ	8373.42
Float collar 2	Ф146.1mm×TP125S×12.34×TP-FJ	8374.60
Casing	Ф146.1mm×TP125S×12.34×TP-FJ	8394.65
Float collar 1	Ф146.1mm×TP125S×12.34×TP-FJ	8395.70
Casing	Ф146.1mm×TP125S×12.34×TP-FJ	8417.06
extended float shoes	Ф146.1mm×TP125S×12.34×TP-FJ	8418.00

Note:(1) The test requires the pocket depth to be below 8350m (ball seat position).

　　2),Casing Performance Data Sheet:

Outer diameter mm	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Outer diameter of coupling mm	Tensile strength kN	Extrusion strength Mpa	Internal pressure strength Mpa
146.1	TP125S	12.34	TP-FJ	40.70	146.1	2462	133.4	101.9

　　3),Casing strength check:

Outer diameter mm	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Section weight t	Tired weight t	Safety factor
Outer diameter mm	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Section weight t	Tired weight t	Tensile	Anti-extrusion	Resistance to internal pressure
146.1	7485～8418	933	TP125S	12.34	TP-FJ	40.70	37.97	37.97	7.91	1.17	3.88

　　4),Strength check of drilling tools fed into liner:

Outer diameter of tail pipe mm	drill pipe	Floating weight (t)	Tension allowance t	Tensile safety factor
F146.1	Ф 139.7mm G105 (wall thickness 10.54mm)* 3000m	207.44	108.79	1.52
F146.1	Ф 101.6mm G105 (wall thickness 10.92mm)* 4400m	120.25	104.95	1.87

Remarks:①The external extrusion pressure of the casing is calculated as 40% hollowed out.②The section weight is empty weight, and the mud density is calculated as 1.43g/cm3.

　　5),Design of Casing Stalknits

well interval	From m	To m	Centralizer type	Placement spacing (m)	Placement quantity (only)
Lower Hanger First Sleeve	7499	7510	Fuzheng Short Section	11	1
Overlapping Segments	7510	7699	Fuzheng Short Section	55	3
Open eye section	7699	8000	Fuzheng Short Section	44	7
Open hole section (well section showing gas layer)	8000	8200	Fuzheng Short Section	22	9
Open eye section	8200	8350	Fuzheng Short Section	44	3
Open hole section (slug section)	8350	8418	Fuzheng Short Section	22	3

6. Cementing construction

At 10:30 on February 9, 2016, the hanger was released, the liner went down to a well depth of 8418m, and the top depth of the back-up tube was 7481.92m;-15:15 cementing preparation;-Cementing at 20:30;-22:00 Short start 15 columns (from well depth to 7051.26m);-3:00 cycle;-4:00 short start 5 columns (from well depth to 6905.96m);-6:00 hold pressure 8MPa waiting for coagulation.

1) Construction records

Sequence	Construction time (min)	Operation content	Workload (m3)	Density (g/cm3)	Displacement (m3/min)	Pressure (MPa)
1	February 9, 16:00~16:10	Manifold pressure test				35
2	15:15～16:30	Injection of pilot slurry	30	1.43	0.54	20
3	16:30～17:15	Injection of barrier fluid	20	1.55	0.54	20
4	17:15～17:25	Flushing fluid	4	1.02	0.54	20-22
5	17:25～17:55	Injection of lead slurry	11	1.88	0.54	22-20
6	17:55～18:08	Injection of tail slurry	6	1.94	0.54	22-20
7	18:08～18:10	Release the drill pipe rubber plug
8	18:12～18:18	Replacing the plug fluid	2	1.55	0.54	20
9	18:18～18:31	replace heavy mud	7	1.80	0.54	20
10	18:31～18:36	Roof protection fluid	2	1.55	0.54	20
11	18:36～20:16	replace the original mud	58.8	1.43	0.54	20-22
12	20:16～20:50	Touch pressure, check backflow				Not pressed
13	20:50～22:00	Unloading cement head, tripping out	15 Pillar
14	22:00-February 10, 3:00	Cycle 1 week	228	1.43	1.2-1.5
15	3:00～4:00	tripping out, continuous grouting	5 Pillars
16	4:00 to 9:00 on February 13	Well shut-in, pressure bouncing and waiting for coagulation				8

2) Cementing quality:

① At 1:30 on February 15, 2016, drill down to a well depth of 7049.7m to find the cement plug surface, with a plug height of 432.22m.

② On February 20, 2016, at 14:30, drill down to a well depth of 8355m (ball seat position) without plug.

③ Electric logging and cementing quality from 8:00 to 19:00 on February 22, 2016. The high quality rate is 93%. The cementing quality is high.

7. Summary of Cementing Well in the 5th Opening

1), latex cement slurry is suitable for deep well high temperature gas well cementing, with great advantages of cement slurry system.

2), slim hole cementing, less displacement, measurement accuracy requirements are very high.

3), small clearance cementing, the rheological characteristics of mud, cement slurry, pre-fluid requirements are high, so that there is a viscosity difference advantage, plus a certain density difference advantage, is conducive to improve the displacement efficiency, cementing quality can be guaranteed.

4), deep well cement slurry performance including pollution test, must be fine and strict, in order to ensure the construction safety.

8. 193.7mm casing back cementing

1. Basic information

1) Well structure (see front)

2) Mud performance

Density g/cm3	Viscosity s	Water loss ml	Mud cake mm	lubrication coefficient	Static shear force	PH
1.75	60	5.0	0.3	≤ 0.07	3.5/5	11

2. Cementing method

The mud density of the wellbore is reduced to 1.75g/cm3, the drilling tool is swept up to 20-30cm on the pull-back barrel, then the cement plug in the pull-back barrel is drilled, and finally the inner surface of the pull-back barrel is milled with a special milling shoe, and the pull-back casing is run into the pull-back casing for cementing.

3. Cementing difficulties and technical measures

1) Difficulties in cementing

① Mud cake is easy to form on the casing wall, which affects the cementing quality.

② After the end of the impact pressure, whether the return plug can smoothly enter the return cylinder and achieve effective sealing is the key to cementing.

③The rapid development of early strength of cement slurry under the condition of large temperature difference of 120 ℃ is the key to ensure the cementing quality.

2) Main technical measures for cementing

① Adjust the mud performance to require density of 1.75g/cm3, viscosity of less than 60s, initial shear ≤ 2, and dynamic shear force ≤ 8Pa.

② In order to improve the cementing quality, the upper casing shall be scraped before running the tieback casing, the mud cake shall be removed, and the inner wall of the tieback barrel shall be cleaned to make it smooth and smooth, which is conducive to the entry of the plug and effective sealing.

③ Carefully add casing centralizer to make casing center effectively.

④ After the casing string is in place, try to insert, make casing compression marks of different pressing tonnage, check the insertion situation, put forward plug after passing the test, select and match the casing short section, so that the pressing tonnage of the back-up cylinder is not less than 20 tons, the sitting tonnage of the casing mandrel is not less than 150 tons, the large displacement cycle, and cementing operation is carried out after normal.

⑤ Before the tieback plug is inserted into the tieback cylinder and pressed down, rinse the sealing surface of the mandrel of the casing head with clean water to ensure the sealing performance.

⑥ Use prestressing technology to cement the well. After the casing head mandrel is hung, inject clear water to pressurize 10MPa in the annulus and wait for coagulation.

⑦ Use high-quality and high-efficiency flushing function of the front liquid system 20m3, density 1.30-1.40g/cm3, viscosity about 60s, reduce the mixing slurry, effectively flush the cementing interface, improve the displacement efficiency of the slurry.

⑧ Jiahua Class G oil well cement is used to control the water loss of cement slurry ≤ 100ml.

Pet-name ruby in order to ensure the cementing quality, the upper collar slurry adopts density 1.90g/cm3 early strong micro-expansion non-permeable anti-channeling cement slurry, the 72-hour strength of the collar slurry is not less than 14MPa; The lower tail slurry 1000m adopts latex cement slurry system.

3) Emergency measures

① Before cement injection, all construction vehicles and equipment shall be put into trial operation, and construction can only be carried out after normal operation. During construction, if the main attack vehicle fails, the standby vehicle shall be activated immediately.

② When high pump pressure occurs in the process of slurry displacement, appropriately reduce the displacement to replace and move the casing up and down; if the wellhead cement slurry has been returned and the pressure continues to rise, the slurry displacement shall be stopped decisively and the plug shall be inserted into the tieback cylinder immediately.

③ The slurry displacement is mainly measured by the tank. If the designed volume is not pressed, the slurry displacement shall be stopped.

4. Cement slurry

1) Test conditions of cement slurry:

The temperature is 110 ℃; The pressure is 114MPa, and the heating and pressurizing time is 70min. The thickening time is measured under constant temperature and pressure.

2) Cement slurry formula:

Lead slurry: Jiahua G + BS500(2%)+ BS600(1.5) + BS300(0.75) + BS100(0.63) + TC-2(1.5)

　　+BS100L(4%)+BS200R(2.5%)+BP-1A(0.25%)

Wet Blend/Dry Blend: 0.44; Dry Blend Pulping Rate: 0.76

Tail slurry: Jiahua Grade G + GW-1(35%)+ BS500(2%)+ BS600(1%)+ BS100(0.7) + BS100L(3%)+ JR

　　(12%)+BS200R(2.5%)+BP-1B(1%)+BS300-J(1%)+WD-2(1%)

Wet Blend/Dry Blend: 0.41; Dry Blend Pulping Rate: 0.74

3) Performance of cement slurry:

Project	Cement slurry collar		Cement slurry tail slurry
Project	Design	Actual	Design	Actual
Density g/cm3	1.90	1.90	1.90	1.90
Water loss ml/7MPa × 30min	≤100	62	≤100	54
Compressive strength (normal temperature × 0.1Mpa × 48h)MPa	≥14.0	8.6	≥14.0	-
Compressive strength (110 ℃× 20.7Mpa × 24h)MPa	≥14.0	15.4	≥14.0	19.6
Initial consistency Bc	≤20	12	≤20	14
100Bc thickening time min	300～360	367	180～240	210
Free fluid%	＜0.5	0	＜0.5	0

　　4),Rheological data of cement slurry

Name	Condition	Φ600	Trillion 300	Φ200	Φ100	Φ6	Φ3
Collar	110℃	220	129	86	54	12	10
tail slurry	110℃	222	130	100	60	10	8

5）Pollution experiment

Cement collar slurry	barrier fluid	Mud	thickening time
70%	20%	10%	>305min
1/3	1/3	1/3	>318min

5. Casing running

Starting from 22:00 on February 26, 2016, running Φ 193.7mm Φ206.4mm composite casing, running 0:00 on February 29 to well depth 5987.14m, circulating mud.

1) Casing string structure: (from top to bottom)

Name	Size × steel grade × wall thickness × button type	Lower depth m
Mandrel Hanger		13.6
Double male short joint	F206.4mm×TP110TSS×19.05mm×TP-NF	15.61
Casing	F206.4mm×TP110TSS×19.05mm×TP-NF	843.48
Transition Section	Ф 206.4mm × TP-NF to Ф 193.7mm × TP-CQ	844.50
Casing	F193.7mm×TP110TSS×12.7mm×TP-CQ	5951.85
throttle float collar	F193.7mm×TP110TSS×12.7mm×TP-CQ	5952.10
Casing	F193.7mm×TP110TSS×12.7mm×TP-CQ	5985.46
Return plug	F193.7mm×TP110TSS×12.7mm×TP-CQ	5985.79

2),Performance data sheet of this layer and upper layer casing:

Outer diameter mm	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Outer diameter of coupling mm	Tensile strength kN	Extrusion strength Mpa	Internal pressure strength Mpa
193.7	TP110TSS	12.7	TP-CQ	58.09	215.9	5477	80.70	87.03
206.4	TP110TSS	19.05	TP-NF	89.97	215.9	5868	133.28	122.55

3),Casing strength check:

Outer diameter mm	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Section weight t	Tired weight t	Safety factor
Outer diameter mm	Well interval m	Length m	Steel Grade	Wall thickness mm	Buckle type	Weight per meter kg/m	Section weight t	Tired weight t	Tensile	Anti-extrusion	Resistance to internal pressure
193.7	843～5986	5144	TP110TSS	12.7	TP-CQ	58.09	301.31	373.29	1.89	1.51	2.02
206.4	0～843	843	TP110TSS	19.05	TP-NF	89.97	71.98	71.98	10.50	11.8	2.84

4),Centralizer placement

Top depth of well interval (m)	Bottom depth of well section (m)	Centralizer type	Centralizer specification (mm)	Placement spacing (m)	Placement quantity (only)
843	5700	Rigidity	193.7mm centralizer	55	90
5700	5986	Rigidity	193.7mm centralizer	22	13

6. Back-up cementing construction

From 6:00 to 9:00 on February 29, 2016, the cycle will be circulated (during which the plug will be plugged back, the pressure will be suppressed by 9MPa, and there will be no pressure drop after stabilizing the pressure for 5min);-Cementing at 17:30, without touching the pressure;-6:00 Hold Pressure 10MPa Wait for Setting.

1) Construction records

Sequence	Construction time	Operation content	Workload (m3)	Density (g/cm3)	Displacement (m3/min)	Pressure (MPa)
1	17:30～17:40	Pipeline pressure test				30
2	18:15～18:30	Flushing Spacer	20	1.4	1～1.4	12～18
3	18:35～19:45	Injection collar slurry	91	1.88	1.2～1.5	22～0
4	19:45～20:08	Injection latex tail slurry	31	1088	1.2～1.5	22～0
5	20:08～20:15	Open gear pin press rubber plug	4.0	1.02	1.0	0
6	20:15～21:45	Open gear pin press rubber plug	128.58	1.75	1.6～0.5	0-21
7	20:45～21:50	Impact pressure				Not pressed
8	21:50～23:00	Lower insertion of return cylinder seating sleeve head
9	~ March 3, 20:00	Ring pressure suppression Hou coagulation				10

Note: ① In order to ensure good sealing of the casing head mandrel, it is required to flush the wellhead while lowering it, first flush with clean water, then flush with air, and the drilling team shall prepare air supply pipelines and joints in advance.

② Reasonably adjust the length of the pipe string. When it is required to press down 20 tons, insert the tieback cylinder completely.

2) Cementing quality

① On March 4, 2016, at 21:30, drill down to a well depth of 5838m to find the cement plug surface (the cement plug height is 114m).

② The sound amplitude was measured at 11:00 on March 7, 2016, and the cementing quality was high.

7. Summary of tieback cementing

1), back cementing scraping pipe, eliminate mud cake, ensure the quality of interface bonding.

2), adding high-efficiency early strength agent, the early strength development of large temperature difference cement slurry is of great benefit.

3), the use of flushing type front liquid effective flushing interface and adhere to large displacement construction, can improve the efficiency of slurry displacement.

4) Prestressed cementing ensures cementing quality

None

HOT BLOG

Repost | A super-deep gas field has been discovered in the Sichuan Basin!

A super‑deep shale gas field containing 235.6 billion cubic meters has been discovered in the Sichuan Basin, with daily production of one million cubic meters—making it the world’s oldest gas‑producing formation. From Fuling to Ziyang, China’s shale gas reserves have surpassed 4 trillion cubic meters, further bolstering energy security.

2026-05-15

China has discovered an ultra-deep shale gas field!

May 13 Sinopec’s “Deep-Earth Project: Sichuan–Chongqing Natural Gas Base” has achieved another breakthrough. The Ministry of Natural Resources has released its mineral exploration results.

2026-05-13

Good News: Sinopec Achieves New Breakthrough in “Deep-Earth Engineering”

Recently, Sinopec’s “Deep-Earth Engineering–Sichuan–Chongqing Natural Gas Base” has once again reported a significant breakthrough. The Yonghong-1 well, a key ultra-deep tight sandstone exploration well deployed by Sinopec Exploration Branch in Bazhong City, Sichuan Province, has successfully tested high-producing gas flows, marking an important new stratigraphic breakthrough in the Jurassic system of the Sichuan Basin. This discovery confirms the favorable exploration and development potential of the Jurassic tight sandstones in the Bazhong area, suggesting the prospect of establishing a new resource base for increasing reserves and boosting production in the Sichuan Basin.

2026-04-25

+862823239080

E-mail: hskj@schsh.com.cn

liu manager of the technical department: +8613330685370

Focus on us

Business License

SEO

Cookie

Our website uses cookies and similar technologies to personalize the advertising shown to you and to help you get the best experience on our website. For more information, see our Privacy & Cookie Policy

Cookie

Required

These cookies are necessary for basic functions such as payment. Standard cookies cannot be turned off and do not store any of your information.

Analyze

These cookies collect information, such as how many people are using our site or which pages are popular, to help us improve the customer experience. Turning these cookies off will mean we can't collect information to improve your experience.

Feature

These cookies enable the website to provide enhanced functionality and personalization. They may be set by us or by third-party providers whose services we have added to our pages. If you do not allow these cookies, some or all of these services may not function properly.

Advertise

These cookies help us understand what you are interested in so that we can show you relevant advertising on other websites. Turning these cookies off will mean we are unable to show you any personalized advertising.