CN-121993088-A - Pressure control method for well cementation operation, sealing device and application thereof

Abstract

The invention relates to the technical field of oil and gas well drilling and completion, in particular to a pressure control method for well cementation operation, a sealing device and application thereof, wherein the pressure control method comprises the steps of judging whether overflow occurs in the well cementation operation process; if so, calculating the well closing casing pressure, calculating the equivalent slurry density or equivalent completion fluid density of the balanced formation pressure according to the well closing casing pressure, calculating the required equivalent wellhead back pressure, keeping wellhead annulus seal, maintaining the equivalent wellhead back pressure obtained by the calculation in the step of maintaining the wellhead by controlling the opening of the throttle valve, gradually increasing the slurry density or the completion fluid density, correspondingly controlling the opening of the throttle valve, and continuing the well cementation operation process. By the pressure control method, the sealing device and the application thereof, the annular pressure profile of the shaft can be controlled during well cementation operation, the underground pressure abnormality can be manually interfered in a plurality of links such as casing running, well cementation and the like, the well control risk of the well cementation operation is greatly improved, and the well cementation operation quality is improved.

Inventors

• ZHAO WENZHUANG
• WANG LEI
• YANG BIN
• GAO YONGWEI
• LIU KEQIANG
• ZHAO HANGBO
• CHEN CAIZHENG
• ZHOU WENBING
• LI XIAOLI
• LI YANZE

Assignees

• 中国石油天然气集团有限公司
• 中国石油集团川庆钻探工程有限公司

Dates

Publication Date

20260508

Application Date

20241105

Claims (10)

1. 1. A pressure control method for well cementation operation is characterized by comprising the following steps: S 1 , judging whether overflow occurs in the well cementation operation process, if so, entering a step S 2 ; S 2 , calculating the well closing casing pressure; S 3 , calculating the equivalent mud density or equivalent completion fluid density for balancing the formation pressure according to the shut-in casing pressure: Wherein ρ When (when) is equivalent mud density or equivalent completion fluid density, P Consumption of is annular circulating pressure consumption, P Shut-in well is well closing casing pressure, g is gravity acceleration, and H is well depth vertical depth; S 4 , calculating required equivalent wellhead back pressure P Returning to : pHui= (ρ when- ρ real) g.H+P consumption Wherein ρ Real world is the actual mud density or the actual completion fluid density; S 5 , maintaining wellhead annulus sealing, and maintaining equivalent wellhead back pressure P Returning to calculated in the step S 4 at the wellhead by controlling the opening of a throttle valve; S 6 , gradually increasing the slurry density or the well completion fluid density, correspondingly controlling the opening of a throttle valve, and continuing the well cementation operation process.
2. 2. A method of controlling pressure for a well cementing operation as recited in claim 1, wherein the well cementing operation comprises a casing running operation and a cementing operation.
3. 3. The method for controlling pressure of well cementing operation according to claim 2, wherein when the fixing operation is a casing running operation, the step S 6 comprises: S 611 , continuing the casing running operation; s 612 , aggravating the density of the completion fluid; S 613 , circularly replacing low-density completion fluid in the well, and gradually opening the throttle valve to a full-open state in the replacement process until overflow is eliminated; s 614 , continuing the casing running operation.
4. 4. The method of claim 3, wherein if the casing is blocked during the well cementing operation, the blocking is eliminated by means of pump-on circulation, casing rotation and casing lifting and lowering.
5. 5. The method for controlling pressure of well cementing operation according to claim 2, wherein when the fixing operation is a cementing operation, the step S 6 comprises: S 621 , gradually increasing the density of cement slurry until the formation pressure can be balanced, and gradually opening a throttle valve to reduce the wellhead back pressure value in the process; S 622 , normal cementing operation; s 623 , maintaining the annular sealing of the wellhead and waiting for solidification; S 624 , after the weather condensation is finished, finishing the operation.
6. 6. The method of claim 5, wherein if the density of the cement slurry is increased in step S 621 and the formation pressure cannot be balanced to the upper limit, the corresponding wellhead back pressure value is maintained at the wellhead all the time by controlling the opening of the throttle valve, and the wellhead is kept to be subjected to waiting solidification until the waiting solidification is finished.
7. 7. The method of claim 6, wherein the back pressure value of the wellhead is recorded and the back pressure is adjusted in time according to the calculation method in step S 4 .
8. 8. A sealing device for well cementation operation is characterized in that the sealing device is used in the pressure control method according to any one of claims 1-7 and used for keeping wellhead annulus sealed.
9. 9. The sealing device for well cementation operation according to claim 8, wherein the sealing device comprises a shell (1), a rotary assembly (2) and a casing string (3), the lower end of the shell (1) is connected with a wellhead blowout preventer stack, the casing string (3) comprises a casing (4) and a centralizer (5) sleeved on the casing (4), the centralizer (5) comprises a plurality of centralizing blocks (6) which are arranged at intervals, the rotary assembly (2) is arranged in the shell (1) and can perform relative rotary motion with the shell (1), an upper rubber core (7) and a lower rubber core (8) for sealing the casing (4) are arranged in the rotary assembly (2), the upper rubber core (7) and the lower rubber core (8) are arranged one above the other, and the distance between the upper rubber core (7) and the lower rubber core (8) is larger than the length of the centralizer (5).
10. 10. Use of a sealing device for cementing operations according to claim 9, wherein: the blocking is eliminated by the modes of pumping circulation, sleeve rotation and sleeve lifting in the process of sleeve operation.

Description

Pressure control method for well cementation operation, sealing device and application thereof Technical Field The invention relates to the technical field of oil and gas well drilling and completion, in particular to a pressure control method for well cementation operation, a sealing device and application thereof. Background At present, the national standard technical specification of petroleum exploitation industry clearly states that before casing is put down, a ram blowout preventer should replace a ram which is consistent with the size of the casing to be put down and test pressure. The purpose of replacing ram blowout preventers is to prevent the annulus from being rapidly controlled when overflow is found in the casing running process, and to reduce formation fluid entering the annulus as much as possible, so that well control accidents are caused. The history of adopting ram blowout preventer equipment and a technological method thereof is long, and the gas equipment and the technological method have the following defects: 1. And disassembling the original ram core of the single ram blowout preventer, replacing the ram core which is consistent with the casing pipe in size, then testing the pressure, and then performing casing pipe running operation after the pressure test is successful. The process is time-consuming and labor-consuming, and the time-consuming long-space well waits for increasing well control risks, and the average valve core replacement time is more than 4 hours. 2. When the original technology encounters stratum overflow, the pressure control can only be carried out through a choke manifold, and the weighting circulation well killing is carried out. The existing choke manifold design is only an emergency device, and does not meet the special requirement of long-time large-displacement circulation. 3. In recent years, with the large-scale development of a side exploratory well, the formation pressure abnormal region often drills narrow safety density window layers such as overflow, leakage, overflow and leakage on the same layer, the polygon and the complexity of the formation are increasingly complex, and the existing casing ram blowout preventer cannot meet the increasingly complex working condition demands. 4. Along with the increasing use of oil and gas resources, the exploration scale of deep wells and ultra-deep wells is also enhanced, and the technical requirement on primary return of well cementation cement paste in well cementation operation is urgent. The low-density and ultra-low-density well cementation cement paste technology brought by the method has urgent requirements on the pressure control well cementation technology in the aspect of balancing the formation pressure, but cannot meet the pressure control well cementation technology requirements under the existing equipment technical conditions. In the prior art, a Chinese patent document with publication number of CN115324483A and publication date of 2022, 11 and 11 is proposed, and the technical scheme disclosed in the patent document is that the whole process sealing and casing pressing method comprises the steps of designing a set of sealing device on a wellhead, wherein the sealing device comprises a pipe joint communicated with the wellhead, an upper sealing structure and a lower sealing structure which are arranged in the pipe joint, opening the upper sealing structure when a casing with a centralizer is arranged, closing an annulus by adopting the lower sealing structure, normally pressing the casing, closing the upper sealing structure when the casing centralizer is arranged in a cavity between the upper sealing structure and the lower sealing structure, opening the lower sealing structure when the upper sealing structure is arranged to finish the cavity closing, continuing casing pressing operation, closing the lower sealing structure again after the casing centralizer is arranged in a shaft as a whole, and discharging the drilling fluid with pressure in the cavity by using a pressure release valve. In the practical use process, the technical scheme has the following problem that the annular pressure profile of the shaft cannot be controlled in the well cementation operation. Disclosure of Invention In order to solve the technical problems, the invention provides a pressure control method, a sealing device and application thereof for well cementation operation, which can control the annular pressure profile of a shaft in well cementation operation, realize manual intervention on underground pressure abnormality in a plurality of links such as casing running, well cementation and the like, greatly improve well control risk of well cementation operation and improve well cementation operation quality. The invention is realized by adopting the following technical scheme: a pressure control method for well cementing operations, comprising the steps of: S 1, judging whether overflow occurs in the well cementatio