Downhole self-absorption pressurized drainage gas production external downhole tool and operation method thereof

Abstract

The invention relates to an external downhole tool for downhole self-absorption pressurization drainage gas production and an operation method thereof. The downhole tool comprises a ground tank, a control valve, a ground pump, a gas inlet coupling, a buoyancy ball, an oil pipe, a liquid inlet coupling and a check valve coupling. The air inlet coupling is arranged at the upper end of the oil pipe, the liquid inlet coupling and the check valve coupling are arranged at the lower end of the oil pipe, and the buoyancy ball is arranged in the oil pipe and used for blocking the air inlet coupling or the liquid inlet coupling. The ground pump is connected with the ground tank through the control valve, and the ground tank is connected with the air inlet coupling through the capillary tube. According to the method, the tank is pressed through the ground, gas in the tank is squeezed into an underground tool, the underground tool discharges liquid through gas injection, and therefore ground control gas drive drainage is achieved. No mechanical friction moving part exists, the service life is longer, overhauling can be completed by mainly maintaining the ground pump, and the maintenance cost is saved.

Description

Technical Field

[0001] The present invention relates to the field of downhole operations of petroleum and natural gas, and more specifically to an external downhole tool for self-priming, pressurized water drainage and gas production and an operation method thereof. Background Art

[0002] As the number of oil and gas wells continues to increase, the problem of water discharge from wellbores is also increasing. Failure to promptly handle the liquid accumulation in the wellbore will directly affect the gas well production volume and efficiency. Therefore, drainage and gas production is an important measure to ensure the production volume and efficiency of natural gas.

[0003] The main feature of the late stage of gas wells is insufficient formation energy, and water accumulation in the wellbore will further restrict the formation gas output, resulting in reduced production or even shutdown. At present, there are three types of drainage methods used at home and abroad: one is the gas dynamic method, including periodic blowdown, optimal pipe string, siphon pipe flushing, etc.; the second is the chemical method, including injection of foam activator, etc.; the third is the mechanical method, such as plunger lifting, deep pumping, etc. The gas dynamic method is based on the principles of reducer fluid mechanics and siphon field, and has certain requirements for bottom hole pressure and gas-water ratio. Foam drainage has certain requirements for the pressure and viscosity of the bottom hole. It must be pressurized or depressurized before production can be carried out. The foam fluid generated in the process will slow down the gas flow rate in the well. It is generally not used for low-pressure and low-yield gas wells. The mechanical method has a wide range of applications and can be well applied to low-pressure and low-yield gas wells, but it has low energy efficiency, high investment, and large losses. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an external downhole self-priming pressurized water drainage and gas production downhole tool with a relatively simple structure and low maintenance difficulty and an operating method thereof.

[0005] The technical solution adopted by the present invention to solve the technical problem is: constructing an underground self-priming pressurized water drainage gas production external underground tool, including a ground tank, a control valve and a ground pump arranged on the ground; and also including an air intake coupling, a buoyancy ball, an oil pipe, a liquid intake coupling and a check valve coupling arranged in the underground;

[0006] The air inlet coupling is arranged at the upper end of the oil pipe, the liquid inlet coupling and the check valve coupling are arranged at the lower end of the oil pipe, the check valve coupling is provided with a first check valve that only allows the accumulated liquid in the well to flow into the oil pipe in one direction, and a second check valve that only allows the liquid in the oil pipe to be discharged outward in one direction; the buoyancy ball is arranged inside the oil pipe to block the air inlet coupling or the liquid inlet coupling;

[0007] The ground pump is connected to a ground tank through a control valve, and the ground tank is connected to the air inlet coupling through a capillary tube.

[0008] According to the above scheme, when the surface tank is pressurized by a surface pump, the gas in the surface tank enters the oil pipe through the air inlet coupling along the capillary tube; the liquid in the oil pipe is discharged through the second one-way valve. After the liquid in the oil pipe is emptied, the buoyancy ball contacts the liquid inlet coupling to close the diameter of the oil pipe.

[0009] According to the above scheme, when the surface tank is depressurized by the surface pump, the gas in the oil pipe is depressurized accordingly, and the accumulated liquid in the well enters the oil pipe through the liquid inlet coupling. The buoyancy ball moves upward and finally contacts the air inlet coupling. The oil pipe is filled with liquid and the water absorption is completed.

[0010] According to the above scheme, the air intake coupling connects the upper and lower adjacent oil pipes, and a side hole is provided on the air intake coupling. The liquid flowing out of the second one-way valve of the lower oil pipe is discharged into the upper oil pipe through the capillary and the side hole.

[0011] According to the above scheme, the oil pipe located at the bottom is connected to the screen through a screen coupling. An introduction head is provided at the lower end of the screen. The extension pipe of the screen coupling extends to the introduction head. The accumulated liquid in the well enters from the side wall of the screen. The liquid is deposited in the introduction head, and then the extension pipe enters the oil pipe through the screen coupling.

[0012] According to the above scheme, two ground tanks are provided, and the two ground tanks are respectively connected to the air intake couplings corresponding to the two oil pipes through capillaries.

[0013] According to the above scheme, the control valve is a two-position four-way valve.

[0014] The present invention also provides an operation method of an external downhole tool for self-priming, pressurized water drainage and gas production, comprising the following steps:

[0015] S1. When the surface tank is pressurized by the surface pump, the gas in the surface tank enters the oil pipe through the air inlet coupling along the capillary tube; the liquid in the oil pipe is discharged through the second one-way valve. After the liquid in the oil pipe is emptied, the buoyancy ball contacts the liquid inlet coupling to close the oil pipe diameter, thus completing the drainage;

[0016] S2. When the surface tank is depressurized by the surface pump, the gas in the oil pipe is depressurized accordingly, and the accumulated liquid in the well enters the oil pipe through the liquid inlet coupling. The buoyancy ball moves upward and finally contacts the air inlet coupling. The oil pipe is filled with liquid and the water absorption is completed.

[0017] The implementation of the downhole self-priming pressurized drainage gas production external downhole tool and its operation method of the present invention has the following beneficial effects:

[0018] 1. The present invention can realize ground pressure injection into the tank, squeeze the gas in the tank into the downhole tool, and the downhole tool discharges the liquid by gas injection, thereby realizing ground-controlled gas drive drainage;

[0019] 2. The downhole tool of the present invention has no mechanical friction moving parts, has a longer service life, and can be repaired by mainly maintaining the surface pump, thus saving maintenance costs;

[0020] 3. The present invention realizes the control of drainage efficiency through a two-position four-way valve, can realize ground gas drive controlled drainage, discharge liquid during gas injection, and collect wellbore accumulated liquid during gas extraction. The process structure is simple and can connect multiple ground equipment and downhole tools at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0022] Figure 1 It is a schematic diagram of the double-stroke structure of the downhole self-priming pressurized water drainage gas production external downhole tool of the present invention;

[0023] Figure 2 It is a schematic diagram of the structure of the underground self-priming pressurized drainage gas production external downhole tool located in the underground part;

[0024] Figure 3 It is a schematic diagram of a screen tube coupling and a screen tube. DETAILED DESCRIPTION

[0025] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0026] like Figure 1-3 As shown, the downhole self-priming pressurized drainage gas production external downhole tool of the present invention includes a surface process and a downhole process, and the surface process includes a surface tank 101, a control valve 102, a surface pump 103, and a capillary 104. The downhole process includes a capillary 104, an air intake coupling 105, a buoyancy ball 106, an oil pipe 107, a liquid intake coupling 108, a check valve coupling 109, a screen coupling 110, a screen 111, and an introduction head 112.

[0027] The surface pump 103 pumps liquid into or extracts liquid from the surface tank 101 through the control valve 102. There is inert gas in the surface tank 101, and the capillary 104 is connected to the surface tank 101 and the downhole process through an elbow. The control valve 102 can realize the circulation reversal of pumping in or extracting liquid by setting the working cycle. The control valve 102 in this embodiment is a two-position four-way valve. The two-position four-way valve can set the reversing cycle, and complete the reversal of drainage and water absorption once per cycle. Through the reversing of the two-position four-way valve, multiple surface tanks 101 can be connected to improve the drainage efficiency of the process. The surface tank 101 is connected to the air intake coupling 105 through the capillary 104. The capillary 104 is fixed on the outer wall of the oil pipe and inserted. The air intake coupling 105 can connect the capillary 104 and the inner cavity of the oil pipe 107.

[0028] When the surface tank 101 is pressurized, liquid enters the tank, causing the gas in the tank to flow into the oil pipe 107 through the air inlet coupling 105 along the capillary 104. The oil pipe 107 is provided with a buoyancy ball 106, and the liquid in the oil pipe 107 is squeezed out through the check valve coupling 109. After the liquid is emptied, the buoyancy ball 106 contacts the liquid inlet coupling 108, closing the diameter of the oil pipe 107. At this time, the pressure in the tank rises, and the drainage is completed.

[0029] When hydraulic oil is pumped out from the ground tank 101, the gas in the oil pipe 107 expands and reduces pressure, and the accumulated liquid in the well enters the oil pipe 107 through the liquid inlet coupling 108. As the amount of liquid increases, the buoyancy ball 106 moves upward and finally contacts the ball seat of the air inlet coupling 105. The oil pipe is filled with liquid, and the water absorption is completed.

[0030] Preferably, the air intake coupling 105 connects and separates the upper and lower oil pipes 107, and the capillary tube 104 injects high-pressure gas into the oil pipe 107 through the air intake coupling 105. The air intake coupling 105 is designed with a side hole, and the liquid in the capillary tube 104 on the other side is discharged to the upper oil pipe 107 through the side hole.

[0031] Preferably, the upper end of the oil pipe 107 is connected to the air inlet coupling 105 , and the lower end is connected to the liquid inlet coupling 108 , and the liquid inlet coupling 108 is connected to the check valve coupling 109 .

[0032] Preferably, the one-way valve coupling 109 realizes one-way flow of liquid at two locations, ensuring that the liquid at the first one-way valve B flows into the first one-way valve B in one direction, preventing the liquid in the first one-way valve B from flowing out. It ensures that the liquid at the second one-way valve A flows out to the capillary 104 in one direction, preventing the liquid in the capillary 104 from flowing in.

[0033] Preferably, the accumulated liquid in the well enters from the side wall of the screen tube 111. Since the screen tube coupling 110 is provided with a small diameter extension tube, and the extension tube is extended to the introduction head 112, the liquid is deposited in the introduction head 112 due to its density being greater than that of air, and then enters the oil pipe along the small diameter extension tube through the screen tube coupling 110, thereby ensuring that gas does not enter the tool and affect the drainage.

[0034] Preferably, the screen collar 110 and the screen 111 can prevent the gas in the wellbore from entering the oil pipe 107 and prevent debris from clogging the tool.

[0035] Preferably, two surface tanks 101 are provided, and the two surface tanks 101 are connected to the air intake couplings 105 corresponding to the two oil pipes 107 through the capillary tubes 104. The present invention as a whole is not limited to the double-stroke structure in the drawings. By adding surface equipment and matching downhole tools, a combination of multi-stroke processes can be realized to further improve drainage efficiency.

[0036] The present invention also provides an operation method of an external downhole tool for self-priming, pressurized water drainage and gas production, comprising the following steps:

[0037] S1. When the surface tank 101 is pressurized by the surface pump 103, the gas in the surface tank 101 enters the oil pipe 107 through the air inlet coupling 105 along the capillary tube 104; the liquid in the oil pipe 107 is discharged through the second one-way valve. After the liquid in the oil pipe 107 is emptied, the buoyancy ball 106 contacts the liquid inlet coupling 108, closes the diameter of the oil pipe 107, and completes the drainage;

[0038] S2. When the surface tank 101 is depressurized by the surface pump 103, the gas in the oil pipe 107 is depressurized accordingly, and the accumulated liquid in the well enters the oil pipe 107 through the liquid inlet coupling 108. The buoyancy ball 106 moves upward and finally contacts the air inlet coupling 105. The oil pipe 107 is filled with liquid and the water absorption is completed.

[0039] When two ground tanks 101 are provided, the operation mode of the double-stroke structure includes the following steps:

[0040] S1. After the tool is connected to the ground, the oil pipe is used to lower the tool to the designed well depth, and the capillary 104 is fixed to the outer wall of the oil pipe during lowering;

[0041] S2, after being lowered into place, the capillary 104 is passed through the wellhead and connected to the surface tank 101; at the same time, after the surface tank 101 is connected to the surface pump 103, hydraulic liquid and inert gas are added into the tank;

[0042] S3, the ground two-position four-way valve is set up and the pump is turned on after the working cycle. When the ground pump 103 increases the pressure to the ground tank 101 on the left through the two-position four-way valve, the ground tank 101 on the right releases the pressure. Thus, the air intake coupling 105, oil pipe 107, liquid intake coupling 108, and check valve coupling 109 located above are used for drainage, and the air intake coupling 105, oil pipe 107, liquid intake coupling 108, and check valve coupling 109 located below are used for water absorption.

[0043] S4. After the first cycle operation is completed, the left ground tank 101 is depressurized by switching the two-position four-way valve, and the right ground tank 101 is pressurized. Thus, the air intake coupling 105, oil pipe 107, liquid intake coupling 108, and check valve coupling 109 located above are used for water absorption, and the air intake coupling 105, oil pipe 107, liquid intake coupling 108, and check valve coupling 109 located below are used for water discharge.

[0044] By repeating the periodic operation of the bidirectional pump in steps S3-S4, the accumulated water in the wellbore can be discharged.

[0045] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A self-priming, pressurized, water-draining and gas-collecting external downhole tool, characterized in that: It comprises a surface tank (101), a control valve (102) and a surface pump (103) arranged on the surface; it also comprises an air intake coupling (105), a buoyancy ball (106), an oil pipe (107), a liquid intake coupling (108) and a check valve coupling (109) arranged underground; The air inlet coupling (105) is arranged at the upper end of the oil pipe (107), the liquid inlet coupling (108) and the check valve coupling (109) are arranged at the lower end of the oil pipe (107), and the check valve coupling (109) is provided with a first check valve that only allows the accumulated liquid in the well to flow into the oil pipe (107) in one direction, and a second check valve that only allows the liquid in the oil pipe (107) to be discharged outward in one direction; the buoyancy ball (106) is arranged inside the oil pipe (107) to block the air inlet coupling (105) or the liquid inlet coupling (108); The surface pump (103) is connected to the surface tank (101) via a control valve (102), and the surface tank (101) is connected to the air intake coupling (105) via a capillary tube (104).

2. The downhole self-priming pressurized water drainage gas production external downhole tool according to claim 1, characterized in that: When the surface tank (101) is pressurized by the surface pump (103), the gas in the surface tank (101) enters the oil pipe (107) through the capillary tube (104) and the air inlet coupling (105); the liquid in the oil pipe (107) is discharged through the second one-way valve. After the liquid in the oil pipe (107) is emptied, the buoyancy ball (106) contacts the liquid inlet coupling (108) to close the diameter of the oil pipe (107).

3. The downhole self-priming pressurized water drainage gas production external downhole tool according to claim 1, characterized in that: When the surface tank (101) is depressurized by the surface pump (103), the gas in the oil pipe (107) is depressurized accordingly, and the accumulated liquid in the well enters the oil pipe (107) through the liquid inlet coupling (108). The buoyancy ball (106) moves upward and finally contacts the air inlet coupling (105), and the oil pipe (107) is filled with liquid, thereby completing the water absorption.

4. The downhole self-priming pressurized water drainage gas production external downhole tool according to claim 1, characterized in that: The air intake coupling (105) connects the upper and lower adjacent oil pipes (107). The air intake coupling (105) is provided with a side hole. The liquid flowing out of the second one-way valve of the lower oil pipe (107) is discharged into the upper oil pipe (107) through the capillary tube (104) and the side hole.

5. The downhole self-priming pressurized water drainage gas production external downhole tool according to claim 1, characterized in that: The oil pipe (107) at the bottom is connected to the screen pipe (111) through a screen pipe coupling (110). An introduction head (112) is provided at the lower end of the screen pipe (111). An extension pipe of the screen pipe coupling (110) extends to the introduction head (112). The accumulated liquid in the well enters through the side wall of the screen pipe (111), and the liquid is deposited in the introduction head (112). Then, the extension pipe enters the oil pipe through the screen pipe coupling (110).

6. The downhole self-priming pressurized water drainage and gas production external downhole tool according to claim 1, characterized in that: Two ground tanks (101) are provided, and the two ground tanks (101) are connected to air intake collars (105) corresponding to the two oil pipes (107) through capillaries (104) respectively.

7. The downhole self-priming pressurized water drainage gas recovery external downhole tool according to claim 6, characterized in that: The control valve (102) is a two-position four-way valve.

8. An operating method of the downhole self-priming pressurized water drainage gas recovery external downhole tool according to claim 1, characterized in that: The steps include: S1. When the surface tank (101) is pressurized by the surface pump (103), the gas in the surface tank (101) enters the oil pipe (107) through the capillary tube (104) and the air inlet coupling (105); the liquid in the oil pipe (107) is discharged through the second one-way valve. After the liquid in the oil pipe (107) is emptied, the buoyancy ball (106) contacts the liquid inlet coupling (108), closes the diameter of the oil pipe (107), and completes the drainage; S2. When the surface tank (101) is depressurized by the surface pump (103), the gas in the oil pipe (107) is depressurized accordingly, and the accumulated liquid in the well enters the oil pipe (107) through the liquid inlet coupling (108). The buoyancy ball (106) moves upward and finally contacts the air inlet coupling (105), and the oil pipe (107) is filled with liquid, completing the water absorption.

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