Extrusion sealing pressure-bearing leak stoppage method based on fine pressure control

Abstract

This invention discloses a pressure-sealing plugging method based on precise pressure control, comprising: S1 preparing the plugging working fluid; S2 lowering the plugging drill string to a designated position downhole and pumping in the plugging working fluid; S3 turning on the rotary blowout preventer to shut in the well and setting a pressure control value; S4 turning on the rotary table or top drive to rotate the drill string; S5 starting the drilling pump to continuously inject the plugging working fluid into the leaking formation; S6 metering the amount of fluid returning from the wellhead, and stopping the pump to stabilize the pressure when the amount of fluid returning from the wellhead increases to be equivalent to the current pumping volume of the drilling pump; S7 increasing the pressure control setting value and continuing pressure-sealing plugging, stopping the pump to stabilize the pressure when the amount of fluid returning from the wellhead increases to be equivalent to the current pumping volume of the drilling pump; S8 repeating S7 multiple times until the pressure control setting value is increased to the target pressure value; S9 adjusting the valve opening to gradually release pressure and open the well, completing the pressure-sealing plugging plugging. This method can precisely control the extrusion sealing pressure, and the drill bit rotates continuously during the extrusion sealing and pressure plugging process, effectively preventing the occurrence of drill bit sticking failure and achieving long-term continuous extrusion sealing.

Description

Technical Field

[0001] This invention relates to the field of oil drilling technology, and specifically to a method for sealing and plugging leaks based on precise pressure control. Background Technology

[0002] Loss in drilling refers to the phenomenon where drilling fluid leaks into the formation under pressure differential during the drilling process of oil and gas wells. In recent years, significant progress has been made in the research of loss-sealing methods and processes both domestically and internationally, among which pressure-bearing loss-sealing technology is widely used. This technology involves selecting loss-sealing materials (which may include cement, chemical gels, particulate matter, etc.) that match the formation characteristics to prepare a working fluid. This fluid is then pumped into the target formation using pumping equipment and a loss-sealing drill string. With the assistance of a blowout preventer (BOP), the working fluid is transported under pressure to fractures, pores, or loss channels in the formation, filling the pores and fractures and compacting them to form a sealing layer of a certain thickness. This sealing layer can withstand a certain pressure, thus improving the formation's pressure-bearing capacity and preventing drilling fluid loss during drilling. While this method offers good pressure-bearing sealing performance, it has certain shortcomings in field drilling applications. Firstly, after conventional blowout preventers (BOPs) are shut in, the wellbore is completely sealed, and controlling the sealing pressure by starting and stopping the pump results in large pressure fluctuations, making precise control difficult. Secondly, during the pressure-bearing sealing process after shutting down the BOP, the drill string remains stationary for extended periods, leading to frequent sticking and jamming. Thirdly, the sealing fluid in the wellbore stratifies due to static settling, resulting in unsatisfactory pressure-bearing sealing. Given these prominent issues, a pressure-bearing sealing method that is easy to control precisely and offers high safety is urgently needed.

[0003] Existing technologies, such as the pressure-sealing plugging method disclosed in application number CN201710333423.9, which discloses a fine sand plugging slurry annular reverse injection and reverse extrusion plugging method, are highly adaptable to different leakage channels, improving the matching ability of the plugging agent to the leakage channels and enabling it to be squeezed into different leakage channels. The fine sand in the plugging slurry easily accumulates in the fractures, forming a high-strength plugging wall after extrusion, making it less prone to well leakage recurrence. The annular reverse injection and reverse extrusion method reduces the movement range of the plugging slurry due to the presence of the drill string in the well, forcing the plugging slurry to enter the leaking layer more easily. The annular reverse injection and reverse extrusion method better suits the gravity settling characteristics of high-density fine sand plugging slurry, allowing the slurry to freely enter the leaking layer during the settling process. Further squeezing through well shut-in forces more plugging slurry into the leaking layer. However, it does not solve the problems of precise control of the extrusion pressure, minimizing fluctuations, drill string sticking risk, and slurry stratification. Summary of the Invention

[0004] The purpose of this invention is to provide a pressure-sealing and leak-sealing method based on precise pressure control, so as to overcome the above-mentioned technical defects.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A pressure-sealing and leak-sealing method based on precise pressure control includes the following steps: S1. Prepare the sealing fluid; S2. Lower the plugging drill string to the designated position downhole, and pump in the plugging working fluid prepared in S1 until the plugging working fluid flows out of the drill string water hole and reaches the leak point; S3. Open the rotary blowout preventer to close the well, adjust the valve opening, and set the control pressure value; S4. Turn on the rotary table or top drive to rotate the drill string; S5. Start the drilling pump and continuously inject plugging fluid into the lost circulation zone; S6. Measure the amount of fluid returned from the wellhead. When the amount of fluid returned from the wellhead increases to be equivalent to the current pumping rate of the drilling pump, stop the pump and stabilize the pressure. S7. Increase the pressure control setting value, continue to control the pressure and continuously inject the plugging fluid. When the amount of fluid returned from the wellhead increases to be equivalent to the current pumping volume of the drilling pump, stop the pump and stabilize the pressure. S8. Repeat step S7 multiple times until the pressure control set value is increased to the target pressure value and stabilized; S9. Adjust the valve opening to gradually release pressure and open the well, completing the pressure sealing and plugging process.

[0006] Furthermore, the preparation method of the plugging working fluid includes the following steps: S101. Prepare a base slurry with properties comparable to drilling fluid, or use the original drilling fluid as the base slurry; S102. Add 5-10% by weight of fiber plugging material, 10-15% by weight of bridge plug plugging agent, and 5-8% by weight of rigid particles to the base slurry, mix evenly, and obtain the plugging working fluid.

[0007] Preferably, the fiber plugging material is XW-1 modified fiber for drilling fluid pressure-bearing plugging agent or XW-2 modified fiber for drilling fluid pressure-bearing plugging agent.

[0008] Preferably, the bridge plug plugging agent is drilling fluid bridge plug plugging agent QD-Ⅰ or drilling fluid bridge plug plugging agent QD-Ⅱ.

[0009] Preferably, the rigid particles are 20-80 mesh calcium carbonate.

[0010] Furthermore, in step S2, the term "the plugging drill bit is lowered to a designated position downhole" specifically means that the plugging drill bit is lowered to a position 10-15 meters above the leakage point.

[0011] Preferably, in step S3, the set pressure control value is 1 / 3 to 1 / 2 of the target pressure value.

[0012] Preferably, in step S4, the drill bit rotates at a speed of 20 to 40 revolutions per minute.

[0013] Preferably, in step S5, the injection rate of the plugging working fluid is 10-15 L / s.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The pressure-sealing and plugging method based on fine pressure control described in this invention can precisely control the pressure of the squeeze sealing. The drill bit rotates continuously during the pressure-sealing and plugging process, effectively preventing the drill bit from sticking and achieving long-term continuous squeeze sealing. At the same time, it agitates the plugging fluid in the well, avoiding stratification and sedimentation. It has strong applicability to field production and is very worthy of promotion and application.

[0015] 2. This invention combines precise pressure control with pressure-sealing and leak-stopping technology by utilizing a rotary pressure control device, thus achieving a simple, reliable, safe, and efficient method that is suitable for on-site use.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a flowchart of a pressure-sealing and leak-sealing method based on precise pressure control. Detailed Implementation

[0018] The invention can be further understood in conjunction with the following detailed description of preferred embodiments and included examples. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. If any definition of a specific term disclosed in the prior art differs from any definition provided herein, the definition provided herein shall prevail.

[0019] In a typical embodiment of this application, such as Figure 1 As shown, a method for sealing pressure-bearing leaks based on precise pressure control is provided, including the following steps: S1. Prepare the sealing fluid, the specific method is as follows: S101. Prepare a base slurry with properties comparable to drilling fluid, or use the original drilling fluid as the base slurry; S102. Add 5-10% by weight of fiber plugging material, 10-15% by weight of bridge plug plugging agent and 5-8% by weight of rigid particles to the base slurry, mix evenly to obtain the plugging working fluid. S2. Lower the plugging drill bit to 10-15 meters above the leak point, and pump in the plugging working fluid prepared in S1 until the plugging working fluid flows out of the drill bit water hole and reaches the leak point. S3. Open the rotary blowout preventer to close the well, adjust the valve opening, and set the control pressure value; S4. Turn on the rotary table or top drive to rotate the drill bit at a speed of 20-40 revolutions per minute; S5. Start the drilling pump and continuously inject plugging fluid into the lost circulation zone at a displacement of 10-15 L / s; S6. Measure the amount of fluid returned from the wellhead. When the amount of fluid returned from the wellhead increases to be equivalent to the current pumping rate of the drilling pump, stop the pump and stabilize the pressure. S7. Increase the pressure control setting value, continue to control the pressure and continuously inject the plugging fluid. When the amount of fluid returned from the wellhead increases to be equivalent to the current pumping volume of the drilling pump, stop the pump and stabilize the pressure. S8. Repeat step S7 multiple times until the pressure control set value is increased to the target pressure value and stabilized; S9. Adjust the valve opening to gradually release pressure and open the well, completing the pressure sealing and plugging process.

[0020] In some preferred embodiments, the fiber plugging material is drilling fluid pressure-bearing plugging agent modified fiber XW-1 or drilling fluid pressure-bearing plugging agent modified fiber XW-2. The bridging plugging agent is drilling fluid bridging plugging agent QD-Ⅰ or drilling fluid bridging plugging agent QD-Ⅱ. The rigid particles are 20-80 mesh calcium carbonate.

[0021] In some preferred embodiments, the pressure control value set in step S3 is 1 / 3 to 1 / 2 of the target pressure value.

[0022] The following specific embodiments illustrate the pressure-sealing and leak-stopping method based on precise pressure control and its effects.

[0023] Example 1 Well H15-3 is a horizontal well with a designed depth of 3408 meters. The target formation is Chang 7. A density of 1.20 g / cm³ is used. 3 When the drilling fluid reached a depth of 1806 meters (vertical depth 1610 meters, well inclination 80°, formation length 7 meters), well leakage occurred at a rate of 30 cubic meters per hour. A pressure-sealing method based on precise pressure control was used to seal the leakage. The implementation steps of this method are as follows: ① Drilling fluid loss occurred at a depth of 1806 meters. Prepare 40 cubic meters of 20% bridge plug plugging working fluid and lower the plugging drill to a depth of 1796 meters.

[0024] ② Pump in 22.5 cubic meters of plugging working fluid and return it from the outlet.

[0025] ③ Turn on the rotary blowout preventer to shut off the well, and set the automatic pressure control value to 0.5 MPa.

[0026] ④ Turn on the rotary table or top drive and rotate the drill string at a speed of 30 revolutions per minute.

[0027] ⑤ Continuously inject the plugging working fluid at a displacement of 10-15L / s and observe the amount of fluid returned from the outlet.

[0028] ⑥ When 1.5 cubic meters are injected, and the amount of liquid returning from the outlet increases significantly to close to the injection volume, stop the pump and stabilize the pressure at 0.5 MPa; then increase the pressure control setting to 1 MPa and continue injection.

[0029] ⑦ When 3.5 cubic meters are injected, and the amount of liquid returning from the outlet increases significantly to close to the injection volume, stop the pump and stabilize the pressure at 1 MPa; increase the pressure control setting to 1.5 MPa and continue injection.

[0030] ⑧ When 5.5 cubic meters are injected, and the amount of liquid returning from the outlet increases significantly to close to the injection volume, stop the pump and stabilize the pressure at 1.5 MPa; increase the pressure control setting to 2.0 MPa and continue injection.

[0031] ⑨ When 8.2 cubic meters are injected, and the amount of liquid returning from the outlet increases significantly to close to the injection volume, stop the pump and stabilize the pressure at 2.0 MPa; then increase the pressure control setting to 2.5 MPa and continue injection.

[0032] ⑩ When 10 cubic meters are squeezed in, the amount of liquid returning from the outlet is close to the amount squeezed in. Stop squeezing, stabilize the pressure at 2.5 MPa, reach the target pressure value, and complete the squeezing and sealing of the leak.

[0033] Usage results: After well H15-3 experienced a leakage rate of 30 cubic meters per hour, a pressure-sealing plugging method based on precise pressure control was successfully used. No drill string sticking occurred after two hours of continuous pressure sealing, and the pressure-bearing equivalent density was 1.35 g / cm³. 3 After pressure sealing, the remaining well section was treated with a density of 1.25–1.30 g / cm³. 3 Drilling fluid was injected until the drilling was completed, and no further drilling fluid loss occurred.

[0034] Example 2: Well H15-1 is a horizontal well with a designed depth of 3603 meters. The target formation is Chang 7. A density of 1.25 g / cm³ is used. 3 When the drilling fluid reached a depth of 3082 meters (vertical depth 1612 meters, well inclination 90°, formation length 7), well leakage occurred at a rate of 25 cubic meters per hour. A pressure-sealing method based on precise pressure control was used to seal the leakage. The implementation steps of this method are as follows: ① Drilling fluid loss occurred at a depth of 3082 meters. Prepare 60 cubic meters of 15% bridge plug plugging working fluid and lower the plugging drill to a depth of 3072 meters.

[0035] ② Pump in 38 cubic meters of plugging working fluid and return it from the outlet.

[0036] ③ Turn on the rotary blowout preventer to shut off the well, and set the automatic pressure control value to 0.5 MPa.

[0037] ④ Turn on the rotary table or top drive and rotate the drill string at a speed of 40 revolutions per minute.

[0038] ⑤ Continuously inject the plugging working fluid at a displacement of 10-15L / s and observe the amount of fluid returned from the outlet.

[0039] ⑥ When 3.6 cubic meters are injected, and the amount of liquid returning from the outlet increases significantly to close to the injection volume, stop the pump and stabilize the pressure at 0.5 MPa; then increase the pressure control setting to 1 MPa and continue injection.

[0040] ⑦ When 8.5 cubic meters are injected, and the amount of liquid returning from the outlet increases significantly to close to the injection volume, stop the pump and stabilize the pressure at 1 MPa; increase the pressure control setting to 1.6 MPa and continue injection.

[0041] ⑧ When 12 cubic meters are squeezed in, the amount of liquid returning from the outlet is close to the amount squeezed in. Stop squeezing, stop the pump and stabilize the pressure at 1.6 MPa to reach the target pressure value, and complete the squeezing and sealing of the leak.

[0042] Usage results: After a wellbore loss at a rate of 25 cubic meters per hour, the leak was successfully plugged using a pressure-sealing method based on precise pressure control. No drill string sticking occurred after 2.5 hours of continuous pressure sealing, and the pressure-bearing equivalent density was 1.35 g / cm³. 3 After pressure sealing, the remaining well section was treated with a density of 1.30–1.32 g / cm³. 3 Drilling fluid was injected until the drilling was completed, and no further drilling fluid loss occurred.

[0043] In summary, the pressure-sealing plugging method based on precise pressure control described in this invention can precisely control the sealing pressure. The drill string rotates continuously during the pressure-sealing plugging process, effectively preventing drill string sticking and enabling long-term continuous sealing. Simultaneously, it agitates the plugging fluid in the well, preventing sedimentation and stratification of the plugging material. It has strong applicability to field production and is highly worthy of widespread application.

[0044] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A method for sealing pressure-bearing leaks based on precise pressure control, characterized in that, Includes the following steps: S1. Prepare the sealing fluid; S2. Lower the plugging drill string to the designated position downhole, and pump in the plugging working fluid prepared in S1 until the plugging working fluid flows out of the drill string water hole and reaches the leak point; S3. Open the rotary blowout preventer to close the well, adjust the valve opening, and set the control pressure value; S4. Turn on the rotary table or top drive to rotate the drill string; S5. Start the drilling pump and continuously inject plugging fluid into the lost circulation zone; S6. Measure the amount of fluid returned from the wellhead. When the amount of fluid returned from the wellhead increases to be equivalent to the current pumping rate of the drilling pump, stop the pump and stabilize the pressure. S7. Increase the pressure control setting value, continue to control the pressure and continuously inject the plugging fluid. When the amount of fluid returned from the wellhead increases to be equivalent to the current pumping volume of the drilling pump, stop the pump and stabilize the pressure. S8. Repeat step S7 multiple times until the pressure control set value is increased to the target pressure value and stabilized; S9. Adjust the valve opening to gradually release pressure and open the well, completing the pressure sealing and plugging process.

2. The method for sealing pressure-bearing leaks based on precise pressure control according to claim 1, characterized in that, In step S1, the preparation method of the plugging working fluid includes the following steps: S101. Prepare a base slurry with properties comparable to drilling fluid, or use the original drilling fluid as the base slurry; S102. Add 5-10% by weight of fiber plugging material, 10-15% by weight of bridge plug plugging agent, and 5-8% by weight of rigid particles to the base slurry, mix evenly, and obtain the plugging working fluid.

3. The method for sealing and plugging leaks based on precise pressure control according to claim 2, characterized in that: The fiber plugging material is either XW-1 or XW-2 modified fiber for drilling fluid pressure-bearing plugging agent.

4. The method for sealing pressure-bearing leaks based on precise pressure control according to claim 2, characterized in that: The bridge plug plugging agent is drilling fluid bridge plug plugging agent QD-Ⅰ or drilling fluid bridge plug plugging agent QD-Ⅱ.

5. The method for sealing pressure-bearing leaks based on precise pressure control according to claim 2, characterized in that: The rigid particles are 20-80 mesh calcium carbonate.

6. The method for sealing pressure-bearing leaks based on precise pressure control according to claim 1, characterized in that: In step S2, the term "the plugging drill bit is lowered to a designated position downhole" specifically means that the plugging drill bit is lowered to a position 10-15 meters above the leakage point.

7. The method for sealing pressure-bearing leaks based on precise pressure control according to claim 1, characterized in that: In step S3, the set pressure control value is 1 / 3 to 1 / 2 of the target pressure value.

8. The method for sealing pressure-bearing leaks based on precise pressure control according to claim 1, characterized in that: In step S4, the drill bit rotates at a speed of 20-40 revolutions per minute.

9. The method for sealing pressure-bearing leaks based on precise pressure control according to claim 1, characterized in that: In step S5, the injection rate of the plugging working fluid is 10-15 L / s.

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