Blowout prevention well completion pipe string in oil and gas active well liner pipe and operation method of blowout prevention well completion pipe string

Abstract

The invention relates to the technical field of petroleum engineering well completion, in particular to a blowout prevention well completion pipe string in a lining pipe of an oil gas active well and an operation method of the blowout prevention well completion pipe string. Comprising a production pipe column and a liner pipe column, the production pipe column is arranged above the liner pipe column, and the production pipe column is connected with the liner pipe column; the liner string comprises a casing packer, a POP valve and a lower oil pipe, the lower oil pipe is arranged on the lower portion of the casing packer, and the POP valve is arranged in the lower oil pipe; the production pipe column comprises an upper oil pipe, a telescopic pipe and a circulating valve which are sequentially connected from top to bottom; the POP valve is arranged between the anchoring sealing back-inserting barrel and the lower oil pipe, upward movement of high-pressure fluid in the oil pipe can be effectively isolated, upward movement of high-pressure fluid in an oil sleeve annulus can be effectively isolated after the casing packer is set, then well control safety during well completion of an oil and gas active well is guaranteed, and meanwhile reservoir pollution caused by leakage of a large amount of drilling fluid is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas well completion in petroleum engineering, and particularly to an anti-blowout completion string inside a liner for an oil and gas active well and an operation method thereof. Background Art

[0002] Well completion is the last link of a drilling project. In oil exploitation, oil and gas well completion includes opening the oil layer, selecting a well completion method, cementing, perforating operations, etc. Well completion methods include: perforating completion method, open-hole completion method, liner completion method, gravel packing completion method. The fractured carbonate reservoir in Shunbei is often completed with a liner. A common liner completion string is as Figure 1 shown. The liner is used to mechanically support the reservoir in the open-hole section to prevent the collapse of the open-hole wellbore and the shutdown of the oil and gas well caused by excessive production pressure difference. A casing packer is used to seal the annulus between the casing and the liner to prevent high-pressure and acidic natural gas from entering the casing, avoid leakage of the casing caused by long-term corrosion under high pressure and acidic media, and improve well control safety.

[0003] However, for carbonate oil and gas active reservoirs, the oil and gas upward migration speed is fast, the lost circulation probability is high, and the safety window is narrow. The existing completion string cannot ensure well control safety during well completion. High-pressure gas moves rapidly upward through the wellbore. After the pressure is released, the volume of the high-pressure gas expands rapidly, and the wellbore liquid column pressure decreases. If the density of the drilling fluid in the wellbore is not properly controlled or the drilling fluid is not replenished in time, well kick and blowout are likely to occur. And high-density drilling fluid or excessive slurry replenishment volume will exacerbate the massive loss of drilling fluid into the formation, causing pollution to the fractured reservoir. Relying on the natural energy of the formation for production often results in difficult production, and additional reservoir stimulation is required, which not only increases the input cost, but also the plugging removal effect of some wells is not ideal.

[0004] Therefore, the present invention provides an anti-blowout completion string inside a liner for an oil and gas active well and an operation method thereof. Summary of the Invention

[0005] The present invention solves the technical problems existing in the prior art, and provides an anti-blowout completion string inside a liner for an oil and gas active well and an operation method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] An anti-blowout completion string inside a liner for an oil and gas active well includes a production string and a liner string. The production string is arranged above the liner string and is connected to the liner string. The liner string includes a casing packer, a POP valve, and a lower tubing. The lower tubing is arranged below the casing packer, and the POP valve is arranged inside the lower tubing. The production string includes an upper tubing, a telescopic pipe, and a circulation valve connected in sequence from top to bottom.

[0008] Further, an anchoring and sealing back - insertion cylinder is arranged inside the casing packer. The upper end of the lower tubing is connected to the anchoring and sealing back - insertion cylinder. An anchoring and sealing back - insertion joint is arranged at the lower end of the circulation valve. The anchoring and sealing back - insertion joint cooperates with the anchoring and sealing back - insertion cylinder to achieve anchoring.

[0009] Furthermore, a downhole safety valve is also arranged on the upper tubing.

[0010] Furthermore, the downhole safety valve is arranged at 100 m below the surface of the well.

[0011] Further, the lower tubing is connected to a screen pipe, and the screen pipe is located at the open - hole section of the horizontal well section.

[0012] Furthermore, the screen pipe is a perforated screen pipe.

[0013] Furthermore, the screen pipe is a slotted screen pipe.

[0014] Furthermore, the end of the screen pipe is communicated with a guide shoe.

[0015] Furthermore, the end of the guide shoe is in an arc - shaped structure.

[0016] Further, the blowout - preventer completion string inside the liner of the oil - gas active well further includes a casing. The casing is arranged in the vertical well section, and the casing packer is arranged inside the lower end of the casing.

[0017] Further, the valve core of the POP valve is made of a drillable and soluble material.

[0018] An operation method of a blowout - preventer completion string inside the liner of an oil - gas active well, which uses any one of the above - mentioned blowout - preventer completion strings inside the liner of an oil - gas active well for operation, includes the following steps:

[0019] S1. Lower the liner string into the oil - gas well with open - hole completion through a drill pipe, and set the casing packer.

[0020] S2. After the casing packer is set, lift and rotate the drill pipe forward to release it.

[0021] S3. Use a solids - free completion fluid to displace all the drilling fluid in the wellbore above the casing packer.

[0022] S4. Lower the production string. After the production string reaches the designated position, back - insert it.

[0023] S5. Inject an annulus protection fluid into the oil - casing annulus until the fluid properties at the inlet and outlet are the same, and complete the fluid displacement operation.

[0024] S6. After the displacement fluid is completed, insert the ball matching the circulation valve. After the matching ball reaches the designated position, apply pressure to the tubing to close the circulation valve, and continue to apply pressure inside the tubing to knock down the valve core of the POP valve to establish an oil and gas production channel.

[0025] Further, it is characterized in that the specific gravity of the solid-free completion fluid required in step S3 is preferably equal to or greater than the gas reservoir pressure coefficient.

[0026] Furthermore, it is characterized in that for a leaking well, the wellbore liquid level is lower than the wellhead, and the specific gravity of the solid-free completion fluid is equal to the gas reservoir pressure coefficient; for a non-leaking well, the wellbore liquid level is at the wellhead, and the specific gravity of the solid-free fluid is higher than the gas reservoir pressure coefficient.

[0027] Furthermore, it is characterized in that for a non-leaking well, the specific gravity of the solid-free fluid is 0.03 - 0.05 higher than the gas reservoir pressure coefficient.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The blowout prevention completion string inside the liner of the oil and gas active well provided by the present invention is provided with a POP valve between the anchor sealing back-in cylinder and the lower tubing, which can effectively isolate the upward movement of the high-pressure fluid inside the tubing. After the casing packer is set, it can effectively isolate the upward movement of the high-pressure fluid in the oil-casing annulus, thereby ensuring well control safety during the completion of the oil and gas active well, and at the same time avoiding reservoir pollution caused by a large amount of drilling fluid leakage.

[0030] (2) The present invention realizes the integration of the liner string and the production string. The string is full-bore, and the dropped valve core is soluble, which is convenient for later operation measures and production logging.

[0031] (3) The production string in the present invention does not carry a casing packer, and the production string can be quickly replaced later, improving the production efficiency of oil and gas wells.

[0032] (4) A small-diameter concentric pipe can be lowered into the production string in the present invention to meet the requirements of gas lift for drainage gas production. Description of the Drawings

[0033] Figure 1 is a schematic structural diagram of the liner completion string in the prior art of the present invention.

[0034] Figure 2 is a schematic structural diagram of the liner string of the present invention.

[0035] Figure 3 is a schematic structural diagram of the connection between the production string and the liner string of the present invention.

[0036] Description of the Reference Numerals:

[0037] 101. Casing, 102. Casing packer, 103. Release tool, 104. Support pipe, 201. Casing, 202. Anchor and seal back - insert cylinder, 203. Casing packer, 204. POP valve, 205. Lower tubing, 206. Screen pipe, 207. Guide shoe, 208. Upper tubing, 209. Downhole safety valve, 210. Telescopic pipe, 211. Circulation valve, 212. Anchor and seal back - insert joint. Detailed implementation mode

[0038] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention. It should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0039] The current conventional liner completion string structure is as Figure 1 shown. An upper tubing and a lower tubing are arranged inside the casing 101. A casing packer 102 is arranged at the bottom of the upper tubing. A release tool 103 is arranged at the upper part of the lower tubing. The lower tubing is connected to the support pipe 104. A liner is used to mechanically support the reservoir in the open - hole section. For carbonate oil - gas active reservoirs, this type of structure is prone to well - kick and blow - out accidents.

[0040] The present invention provides an anti - blowout completion string inside the liner for an oil - gas active well, including a production string and a liner string. The production string is arranged above the liner string and is connected to the liner string. As Figure 2 shown, the liner string includes an anchor and seal back - insert cylinder 202, a casing packer 203, a POP valve 204, a lower tubing 205, and a casing 201. The casing 201 is arranged in the vertical well section. The casing packer 203 is arranged inside the lower end of the casing 201. The anchor and seal back - insert cylinder 202 is connected to the lower tubing 205. The casing packer 203 is arranged outside the anchor and seal back - insert cylinder 202. The POP valve 204 is arranged inside the lower tubing 205.

[0041] The lower tubing 205 is connected to the screen pipe 206, and the screen pipe 206 is located at the open-hole section of the horizontal well section. The screen pipe 206 is a perforated screen pipe or a slotted screen pipe, and the position of the screen pipe 206 is opposite to the favorable reservoir body. The end of the screen pipe 206 is communicated with the guide shoe 207. The end of the guide shoe 207 is in an arc shape, such as a hemispherical shape, and no through holes are provided at the guide shoe 207 to prevent debris, mud mixtures, etc. from blocking the holes. The guide shoe 207 is located at the bottom of the liner string, which is convenient for the liner string to be lowered into the well.

[0042] Among them, the valve core of the POP valve 204 is made of a drillable and soluble material, which dissolves rapidly in the high-temperature formation water environment underground. After dissolution, it is in a powder state and will not block the tubing and the wellhead choke.

[0043] As Figure 3 shown, the production string includes an upper tubing 208, a telescopic pipe 210, a circulation valve 211, and an anchor seal back-off joint 212 connected in sequence from top to bottom. The circulation valve 211 is located between the telescopic pipe 210 and the anchor seal back-off joint 212, and the anchor seal back-off joint 212 cooperates with the anchor seal back-off cylinder 202 to achieve anchoring.

[0044] An underground safety valve 209 is also provided on the upper tubing 208. The underground safety valve 209 is installed at 100 m underground and can achieve emergency well shut-in underground.

[0045] After the casing packer 203 is set and released, the drilling fluid in the wellbore above the casing packer 203 is completely displaced with a solids-free completion fluid. The displacement and well flushing displacement are increased as much as possible to ensure the cleanliness of the wellbore above the casing packer 203 and prevent solid-phase deposition from blocking the POP valve 204. The specific gravity of the solids-free completion fluid is recommended to be equal to or slightly greater than the gas reservoir pressure coefficient to ensure well control safety during the completion operation. For a leaking well, the wellbore liquid level is below the wellhead, and the specific gravity of the solids-free completion fluid is equal to the gas reservoir pressure coefficient; for a non-leaking well, the wellbore liquid level is at the wellhead, and the specific gravity of the solids-free completion fluid is 0.03 - 0.05 higher than the gas reservoir pressure coefficient. The POP valve 204 can effectively isolate the upward movement of the high-pressure fluid in the tubing, and after the casing packer 203 is set, it can effectively isolate the upward movement of the high-pressure fluid in the casing-tubing annulus, thereby ensuring that the entire wellbore is in a safe and controllable state.

[0046] After the liner string is released, the wellbore is already in a safe and controllable state. As Figure 3For the production string shown, the telescopic pipe 210 is located above the circulation valve 211 and as close to the circulation valve 211 as possible. It is run in with contraction (with pins), and the weight of the tubing or tool suspended at the bottom of the telescopic pipe 210 is minimized as much as possible to avoid shearing of the pins due to uncontrollable external forces during the running-in of the telescopic pipe 210 or the backinsertion of the tubing, which may cause premature separation and thus fail to ensure the safety of the completion string under the acid fracturing construction conditions. The circulation valve 211 is located above the anchor and seal backinsertion joint 212 and as close to the anchor and seal backinsertion joint 212 as possible. The fluid inlet hole is normally open in the downhole state. The anchor and seal backinsertion joint 212 is located at the bottom of the production string. After backinsertion with the anchor and seal backinsertion barrel 202, it realizes the functions of anchoring and sealing. After backinsertion, the liner string and the production string are integrated, facilitating subsequent workovers and production logging.

[0047] After the production string is backinserted and the gas production wellhead device is installed, the solid-free completion fluid in the wellbore is displaced out of the wellhead through the circulation valve 211 using the annulus protection fluid slurry. The displacement rate is increased as much as possible to flush the inner cavity of the tubing above the POP valve 204. A ball is dropped to close the circulation valve 211. The valve core of the POP valve 204 is knocked down by gradually applying positive pressure inside the tubing. The valve core falls into the liner above the guide shoe 207. The valve core is made of a drillable and soluble material, which rapidly dissolves in the high-temperature formation water environment downhole and becomes powdery after dissolution, without blocking the tubing and the wellhead choke.

[0048] When the production string needs to be replaced due to factors such as leakage or severe corrosion in the later stage, the tubing is pressured with a kill fluid in a flat push manner. The recommended specific gravity of the kill fluid is equal to or slightly greater than the gas reservoir pressure coefficient by 0.03 - 0.05. After installing the wellhead blowout preventer, the tubing is lifted and rotated clockwise to disengage the anchor and seal backinsertion joint 212 from the anchor and seal backinsertion barrel 202. After circulating and washing the well with the kill fluid until the fluid properties at the inlet and outlet are the same, the original production string in the well is pulled out, and a new production string is run in and backinserted. The production string does not carry a casing packer, making the running and pulling operations safe and convenient.

[0049] When water production occurs in the formation in the later stage, a small-diameter concentric pipe can be run into the production string, and the gas lift method for water drainage and gas production can be adopted. Nitrogen is injected into the production string, and gas production is carried out through the small-diameter concentric pipe.

[0050] The present invention also provides an operation method for a blowout prevention completion string in the liner of an oil and gas active well, comprising the following steps:

[0051] S1. Run the liner string into the oil and gas well with open-hole completion through the drill pipe, and set the casing packer 203;

[0052] S2. After the casing packer 203 is set, lift and rotate the drill pipe clockwise to release it;

[0053] S3. Displace all the drilling fluid in the wellbore above the casing packer 203 with solid-free completion fluid;

[0054] S4, lowering the production string, and inserting it back after it reaches the designated position;

[0055] S5. First, inject annular protection liquid with a specific gravity of 1.02 into the casing annulus in a small displacement. After the circulation is unobstructed, inject in a large displacement until the inlet and outlet liquid properties are consistent, completing the liquid replacement operation;

[0056] S6. After the fluid replacement is completed, the supporting ball of the circulation valve 211 is put in. After the supporting ball reaches the designated position, the oil pipe is pressurized to close the circulation valve 211. The oil pipe is further pressurized to knock down the valve core of the POP valve 204 to establish an oil and gas production channel.

[0057] Furthermore, the specific gravity of the solid-free completion fluid required for step S3 is preferably equal to or slightly greater than the gas layer pressure coefficient; for lost circulation wells, the wellbore liquid level is lower than the wellhead, and the specific gravity of the solid-free completion fluid is equal to the gas layer pressure coefficient; for non-lost circulation wells, the wellbore liquid level is at the wellhead, and the specific gravity of the solid-free liquid is higher than the gas layer pressure coefficient, and the specific gravity of the solid-free liquid is preferably 0.03-0.05 higher than the gas layer pressure coefficient.

[0058] Furthermore, when the production tubing needs to be replaced due to leakage or severe corrosion, the well is killed by horizontal push in the tubing, and the specific gravity of the killing fluid is preferably equal to or greater than the gas layer pressure coefficient of 0.03-0.05.

[0059] Example

[0060] Take Shunbei Oil and Gas Field as an example. This oil and gas field is high pressure, high yield, high hydrogen sulfide content, and the oil and gas reservoir is buried at a depth of about 7500-8000m. The pressure coefficient of the Yijianfang and Yingshan formation gas layers is about 1.24, and the gas layer pressure is about 91-97MPa. The reservoir fractures and cracks are developed, and the probability of drilling loss is high. The oil and gas are relatively active, and the hydrogen sulfide content is high. The well control risk of completion operations is extremely high. In the early stage, the liner string was dropped by hand. During the period when the production string was lowered, the wellbore was always in an unstable state of loss and leakage. The well control risk was extremely high. At the same time, a large amount of drilling fluid leakage could easily cause reservoir pollution. The production string uses a completion string that lifts up to unseal the packer. After the production string leaks, the tubing is generally reversed or cable cutting is used to first pull out part of the tubing, and then the casing packer is salvaged. However, the salvage cycle is long, complex factors are uncontrollable, and replacement is difficult.

[0061] By adopting the blowout prevention completion string in the liner of an active oil and gas well provided by the present invention, for an oil and gas well completed in an open hole, the liner string can be lowered using a drill pipe. Since the drill pipe is usually lowered in an assembled column, the lowering speed is fast, which can reduce the empty wellbore time and reduce the well control risk.

[0062] After the casing packer 203 is set, the wellbore above the casing packer 203 is isolated from the formation and in a stable state. The drill pipe is lifted and rotated clockwise to be run in to achieve releasing. This well is a lost circulation well. The designed mud weight for killing the well is equal to the formation pressure coefficient. Circulate and displace the mud with a large displacement until the fluid properties at the inlet and outlet are the same. Even if the casing packer 203 and the POP valve 204 are in a leaking state, the wellhead is in a safe and controllable state.

[0063] After the well killing is stable, the drill pipe run in can be safely and quickly pulled out, and then the production string is run in. Since the production string uses 4-1 / 2″ tubing with gas-tight connections and is equipped with a downhole safety valve 209 and the hydraulic pipeline supporting the downhole safety valve, the running speed of the production string is relatively slow. However, the wellbore is in a stable state, and the well control risk during running in the production string is relatively low.

[0064] After the production string is run to the designed depth, it is back inserted, the tubing hanger is set, the wellhead is installed, pressure tested, the pipelines are connected. First, inject the annulus protection fluid with a specific gravity of 1.02 into the annulus between the tubing and the casing at a small displacement. After the circulation is smooth, inject it at a large displacement until the fluid properties at the inlet and outlet are the same. Since the wellbore is in a stable state, the casing pressure is only the frictional resistance of the fluid during displacement, without the back pressure caused by the formation pressure.

[0065] After the displacement is completed, the ball matching the circulation valve 211 is dropped in. After the ball reaches the position, pressure is applied to the tubing to close the circulation valve 211. Then, continue to apply pressure to the tubing to knock down the valve core of the easily drillable POP valve 204 to establish the oil and gas production channel.

[0066] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than limiting the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art shall not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A blowout preventer completion string inside the liner of an oil and gas active well, characterized in that, It includes a production string and a liner string. The production string is arranged above the liner string and the production string is connected to the liner string. It is characterized in that the liner string includes a casing packer, a POP valve, and a lower tubing string. The lower tubing string is arranged below the casing packer, and the POP valve is arranged inside the lower tubing string. The production string includes an upper tubing string, a telescopic pipe, and a circulation valve that are connected in sequence from top to bottom.

2. The blowout preventer completion string inside the liner of the oil and gas active well according to claim 1, characterized in that An anchor sealing and backinsertion cylinder is arranged inside the casing packer. The upper end of the lower tubing string is connected to the anchor sealing and backinsertion cylinder. An anchor sealing and backinsertion joint is arranged at the lower end of the circulation valve. The anchor sealing and backinsertion joint cooperates with the anchor sealing and backinsertion cylinder to achieve anchoring.

3. The blowout preventer completion string inside the liner of the oil and gas active well according to claim 2, characterized in that, A downhole safety valve is also arranged on the upper tubing string.

4. The blowout preventer completion string inside the liner of the oil and gas active well according to claim 3, wherein, The downhole safety valve is arranged at 100 m below the wellhead.

5. The blowout preventer completion string inside the liner of the oil and gas active well according to claim 1, characterized in that, The lower tubing string is connected to a screen pipe, and the screen pipe is located at the open hole section of the horizontal well section.

6. The blowout preventer completion string inside the liner of the oil and gas active well according to claim 5, characterized in that, The screen pipe is a perforated screen pipe.

7. The blowout prevention completion string inside the liner of an oil and gas active well according to claim 5, wherein The screen pipe is a slotted screen pipe.

8. The blowout preventer completion string inside the liner of the oil and gas active well according to claim 5, characterized in that, The end of the screen pipe is communicated with a guide shoe.

9. The blowout preventer completion string inside the liner of an oil and gas active well according to claim 8, characterized in that, The end of the guide shoe is in an arc-shaped structure.

10. The blowout preventer completion string inside the liner of the oil and gas active well according to claim 1, characterized in that, The blowout preventer completion string inside the liner of the oil and gas active well also includes a casing, and the casing is arranged in the vertical well section. The casing packer is arranged inside the lower end of the casing.

11. The blowout prevention completion string inside the liner of the oil and gas active well according to claim 1, characterized in that, The valve core of the POP valve is made of a drillable and soluble material.

12. An operating method for an inner blowout preventer completion string in a liner of an oil and gas active well, characterized in that, Operating with a blowout preventer completion string inside the liner of an oil and gas active well according to any one of claims 1-11 includes the following steps: S1. Lower the liner string into the oil and gas well with open hole completion through a drill pipe, and set the casing packer. S2. After the casing packer is set, lift and rotate the drill pipe forward to release it. S3. Displace all the drilling fluid in the wellbore above the casing packer with a solids-free completion fluid. S4. Lower the production string, and backinsert it after it reaches the designated position. S5. Inject an annulus protection fluid into the oil-casing annulus until the fluid properties at the inlet and outlet are the same, and complete the displacement operation. S6. After the displacement is completed, drop the matching ball for the circulation valve. After the matching ball reaches the designated position, apply pressure to the tubing to close the circulation valve, and continue to apply pressure to the tubing to knock down the valve core of the POP valve to establish an oil and gas production channel.

13. The operation method of the blowout preventer completion string in the liner of an oil and gas active well according to claim 12, characterized in that, The specific gravity of the solids-free completion fluid required in step S3 is equal to or greater than the gas reservoir pressure coefficient.

14. The operating method of an anti-blowout completion string in the liner of an oil and gas active well according to claim 13, wherein For a lost circulation well, the wellbore liquid level is lower than the wellhead, and the specific gravity of the solids-free completion fluid is equal to the gas reservoir pressure coefficient; for a non-lost circulation well, the wellbore liquid level is at the wellhead, and the specific gravity of the solids-free fluid is higher than the gas reservoir pressure coefficient.

15. The operating method of an anti-blowout completion string in the liner of an oil and gas active well according to claim 14, characterized in that, For a non-lost circulation well, the specific gravity of the solids-free fluid is 0.03-0.05 higher than the gas reservoir pressure coefficient.

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