Oil-water valve controlled pipe string and same-well injection-production process using the same

Abstract

The present invention relates to the technical field of downhole operation tools, and specifically discloses an oil-water valve-controlled pipe string and a same-well injection and production process method using the pipe string. The design can integrate a reinjection valve, an oil extraction valve, and a water extraction valve on the pipe string, and can link the water extraction valve to open when the reinjection valve is opened, and link the oil extraction valve to close when the water extraction valve is opened, making the switching between oil production and water extraction and injection operations more convenient and flexible, laying the foundation for realizing the same-well injection and production process.

Description

Technical Field

[0001] The present invention relates to the technical field of downhole operation tools, and in particular to an oil-water valve-controlled pipe string and a same-well injection-production process method using the pipe string. Background Art

[0002] The same-well injection-production technology is an important technical measure to achieve economically sustainable production in the late stage of oil fields with extremely high water cut.

[0003] The same-well injection-production technology mainly uses downhole packers to separate the production layer and the reinjection layer to form two independent pressure systems. The oil production pump and water injection pump are arranged downhole to operate simultaneously.

[0004] However, current downhole oil-water separation and simultaneous injection and production technologies have also revealed many shortcomings through field trials. For example, the existing technology uses dual pumps in a single well, which is expensive. Furthermore, driving the dual pumps simultaneously requires high torque, which costs around 300,000 yuan to achieve this output capacity. The power supply cost is also very high, making it unfavorable for future industrial promotion and application.

[0005] Therefore, it is necessary to develop an oil-water valve-controlled pipe string that can be used in conjunction with a single injection and production pump to achieve the process distribution of water extraction, oil production and reinjection. Summary of the Invention

[0006] The purpose of the present invention is to address the defects of the existing technology and provide an oil-water valve-controlled pipe string and a same-well injection and production process method using the pipe string. The design can integrate a reinjection valve, an oil extraction valve and a water extraction valve on the pipe string, and can link the water extraction valve to open when the reinjection valve is opened, and link the oil extraction valve to close when the water extraction valve is opened, so that the switching between oil production operations and water extraction and injection operations is more convenient and flexible, laying the foundation for realizing the same-well injection and production process.

[0007] The technical solution of the present invention is: an oil-water valve controlled injection and production string comprises an injection valve, a bridge joint and an oil-water valve connected in sequence from top to bottom, wherein a first channel and a second channel are opened on the upper wall of the bridge joint;

[0008] The water injection valve includes a first outer cylinder, the bottom of the first outer cylinder is connected to the outer peripheral side of the top of the bridge joint, an upper tube is coaxially arranged in the cavity of the first outer cylinder, the bottom of the upper tube is connected to the inner peripheral side of the top of the bridge joint, and a first annular flow channel is formed between the first outer cylinder and the upper tube;

[0009] A conical valve head is provided in the first annular flow channel and is connected to the outer side of the upper tube in a sliding sealing manner. The inner circumferential surface of the first outer cylinder is provided with a conical first sealing surface that cooperates with the conical valve head to open and close the first annular flow channel. The conical valve head is downwardly connected to a valve stem. A second annular flow channel is provided between the valve stem and the upper tube, and a first through hole is provided on the water injection valve stem to connect the first annular flow channel with the second annular flow channel.

[0010] A piston portion is provided at the middle portion of the outer side of the valve stem and is slidably and sealingly matched with the inner wall of the first outer cylinder. A sliding seat and a fixed seat are respectively provided on the upper and lower sides of the piston portion in the cavity of the first outer cylinder. The sliding seat and the fixed seat cooperate with the piston portion to form an upper pressure chamber and a lower pressure chamber for driving the piston portion to move up and down.

[0011] The fixing seat is provided with a third channel and a fourth channel, the third channel is connected to the first channel, and the fourth channel is connected to the second channel via a pressure transmission tube. The first outer cylinder wall is provided with a pressure injection channel connected to the upper pressure chamber and the fourth channel, and an upper water injection channel connected to the lower pressure chamber and the first channel.

[0012] The oil-water valve includes a second outer cylinder, the top of which is connected to the outer peripheral side of the bottom of the bridge joint, the bottom of which is connected to a bridge joint, and the wall of the bridge joint is provided with an inner oil production channel and an outer water injection channel;

[0013] An oil-water pipe is coaxially provided in the second outer cylinder, an oil hole is provided in the middle of the oil-water pipe, an oil-water valve sleeve is slidably and sealingly connected to the lower outer portion of the oil-water pipe, a valve core is coaxially arranged in the oil-water valve sleeve, a conical second sealing surface is provided at the bottom of the oil-water pipe to cooperate with the valve core head, a second through hole is provided on the wall of the valve core, a lower pipe is slidably and sealingly connected to the lower inner portion of the oil-water valve sleeve, and the lower end of the outer wall of the lower pipe is connected to the inner wall of the bridge joint;

[0014] The second outer cylinder is provided with a pressure transmission seat, a piston cylinder and a piston sleeve from top to bottom in sequence, an upper step portion and a lower step portion are provided in the second outer cylinder, and an upper flow channel and a lower flow channel are opened on the upper step portion and the lower step portion, the lower flow channel is connected with the external water injection channel, the bottom of the piston sleeve is installed in the top inner cavity of the bridge joint, the middle part of the piston sleeve is provided with an annular boss which is in contact and sealed with the lower step portion, an annular gap flow channel is provided between the piston sleeve and the lower tube, the top of the piston sleeve and the bottom of the oil-water valve sleeve are provided with a third sealing surface which cooperates with each other to open and close the gap flow channel, when the gap flow channel is opened, the valve core head cooperates with the second sealing surface to close the bottom channel of the oil-water pipe, and when the gap flow channel is closed, the valve core moves downward to open the bottom channel of the oil-water pipe;

[0015] The lower end of the piston cylinder is slidably connected to the annulus between the lower step portion and the upper end of the piston sleeve, and a lower piston chamber is formed between the bottom of the piston cylinder and the annular boss. A well pressure channel is provided on the annular boss to connect the lower piston chamber with the external water injection channel. An oil flow channel is opened on the wall of the piston cylinder to connect the oil hole and the gap flow channel.

[0016] The upper end of the piston cylinder is slidably connected in the annulus between the upper step portion and the oil-water pipe. The pressure transmission seat is installed between the upper step portion and the oil-water pipe, and an upper piston cavity for driving the piston cylinder is formed between the pressure transmission seat and the piston cylinder. The pressure transmission seat is provided with a pressure transmission channel connecting the second channel with the piston cavity, and a flow groove connecting the first channel with the upper flow channel below.

[0017] Preferably, the bottom of the lower tube is downwardly connected to a water intake pipe.

[0018] Preferably, an oil extraction pipe is downwardly connected to the inner peripheral side of the bridge joint, and an annular oil extraction channel is formed between the oil extraction pipe and the water extraction pipe. The oil extraction channel is connected to the gap flow channel through the inner oil production channel of the bridge joint.

[0019] Preferably, a compensation pipe is downwardly connected to the outer peripheral side of the bridge joint, and an annular space reinjection channel is formed between the compensation pipe and the oil extraction pipe.

[0020] A same-well injection and production process method, using the above-mentioned oil-water valve to control the injection and production string;

[0021] The same-well injection-production process comprises the following steps:

[0022] First, connect the inlet of the injection pump to the upper pipe to form a combined pipeline for the water and oil extraction pipelines. The top of the piston sleeve contacts the third sealing surface at the bottom of the oil-water valve sleeve to form an oil extraction valve, and the head of the valve core contacts the second sealing surface at the bottom of the oil-water pipe to form a water extraction valve.

[0023] Then, the outlet end of the injection pump is divided into two paths. One path is connected to the production pipeline pumped out of the surface, and a production valve is installed on the production pipeline. The other path is connected to the first annular flow channel as a reinjection pipeline pumped into the well. The conical valve head and the first sealing surface cooperate to form a reinjection valve.

[0024] During water injection operation: hydraulic pressure is injected into the injection channel. A part of the hydraulic pressure enters the upper pressure chamber, pushing the piston part to drive the valve stem and the conical valve head downward, so that the conical valve head is separated from the first sealing surface, thereby opening the return valve. The other part of the hydraulic pressure enters the piston chamber through the fourth channel, the pressure transmission pipe, the second channel, and the pressure transmission channel, pushing the piston cylinder to drive the oil-water valve sleeve and the valve core downward, so that the valve core head is separated from the second sealing surface, thereby opening the water intake valve and making the top of the piston sleeve contact and cooperate with the bottom of the oil-water valve sleeve to close the oil intake valve.

[0025] Downhole water enters the oil-water pipe through the lower pipe, the inner cavity of the valve core, and the second through hole, and then enters the injection pump through the inner cavity of the bridge joint and the upper pipe. The injection pump then injects water back into the downhole water injection layer through the first annular flow channel, the first through hole, the first channel, the upper flow channel, the lower flow channel, and the external water injection channel;

[0026] During oil production operation: open the production valve and stop injecting hydraulic pressure into the injection and pressure channel. The well pressure enters the lower piston chamber through the external water injection channel and the well pressure channel, pushing the piston cylinder to drive the oil-water valve sleeve and the valve core upward, so that the head of the valve core contacts the second sealing surface, thereby closing the water intake valve and separating the top of the piston sleeve from the bottom of the oil-water valve sleeve, opening the oil intake valve;

[0027] The well pressure also enters the lower pressure chamber through the lower flow channel of the external water injection channel, the upper flow channel, the first channel, and the upper water injection channel, thereby pushing the piston to drive the valve stem and the conical valve head upward, so that the conical valve head contacts and cooperates with the first sealing surface, thereby closing the re-injection valve;

[0028] The oil in the well enters the oil-water pipe cavity through the internal oil production channel, gap flow channel, oil flow channel, and oil hole, and then enters the injection pump through the inner cavity of the bridge joint and the inner cavity of the upper pipe. The injection pump pumps the oil to the ground through the production pipeline.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The oil-water valve control string integrates the back-injection valve, oil extraction valve and water extraction valve. When the back-injection valve is opened, the water extraction valve can be opened in conjunction with it, and when the water extraction valve is opened, the oil extraction valve can be closed in conjunction with it, making the switching between oil production and water extraction and injection operations more convenient and flexible, laying the foundation for the realization of the same-well injection and production technology.

[0031] This process method can adopt a single pump operation structure with high stability. The single pump is matched with a set of oil production pipelines and a set of separation water reinjection pipelines. The oil production operation and water injection operation can be switched at will according to the operation needs. It is very flexible and convenient. More importantly, the use of a single pump in the same well to drive the pump has much lower requirements than a single machine to drive two pumps. Therefore, the production and maintenance costs are also much lower. This is also the main reason for the large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the upper structure of the present invention in a water-filled state;

[0033] Figure 2 This is a schematic diagram of the lower structure of the present invention in a water-filled state;

[0034] Figure 3 Schematic diagram of the upper structure of the present invention in the oil production state;

[0035] Figure 4This is a schematic diagram of the lower structure of the present invention in the oil production state;

[0036] Figure 5 Schematic diagram of the process flow;

[0037] In the picture:

[0038] 1. Upper tube, 2. First outer cylinder, 3. Conical valve head, 4. Sliding seat, 5. Valve stem, 6. Fixed seat, 7. Upper water injection channel, 8. Bridge joint, 9. Second outer cylinder, 10. Flow trough;

[0039] 11. Pressure transmission seat, 12. Upper flow channel, 13. Oil and water pipes, 14. Piston cylinder, 15. Oil and water valve sleeve, 16. Lower flow channel, 17. Piston sleeve, 18. Gap flow channel, 19. Bridge joint, 20. External water injection channel;

[0040] 21. Reinjection channel, 22. Oil extraction channel, 23. First annular flow channel, 24. Pressure injection channel, 25. First sealing surface, 26. First through hole, 27. Second annular flow channel, 28. Upper pressure chamber, 29. Piston portion, 30. Lower pressure chamber;

[0041] 31. Third channel, 32. Fourth channel, 33. Pressure transmission tube, 34. First channel, 35. Second channel, 36. Pressure transmission channel, 37. Upper step, 38. Upper piston chamber, 39. Second sealing surface, 40. Valve core;

[0042] 41. Third sealing surface, 42. Lower step, 43. Annular boss, 44. Lower pipe, 45. Internal oil production channel, 46. Compensating pipe, 47. Water intake pipe, 48. Oil intake pipe, 49. Reinjection valve, 50. Water intake valve;

[0043] 51. Oil extraction valve, 52. Lower piston chamber, 53. Well pressure channel, 54. Oil hole, 55. Oil flow channel, 56. Second through hole, 57. Injection and production pump, 58. Production valve. DETAILED DESCRIPTION

[0044] The present invention is further described below with reference to the accompanying drawings and embodiments. Example 1

[0045] like Figures 1 to 5 The oil-water valve-controlled injection and production string includes an injection valve, a bridge joint 8 and an oil-water valve connected in sequence from top to bottom. A first channel 34 and a second channel 35 are opened on the upper wall of the bridge joint 8.

[0046] The water injection valve includes a first outer cylinder 2, the bottom of the first outer cylinder 2 is connected to the outer peripheral side of the top of the bridge joint 8, an upper tube 1 is coaxially provided in the cavity of the first outer cylinder 2, the bottom of the upper tube 1 is connected to the inner peripheral side of the top of the bridge joint 8, and a first annular flow channel 23 is formed between the first outer cylinder 2 and the upper tube 1.

[0047] A conical valve head 3 is provided in the first annular space flow channel 23 and is slidingly sealed and connected to the outside of the upper tube 1. The inner circumference of the first outer cylinder 2 is provided with a conical first sealing surface 25 that cooperates with the conical valve head 3 to open and close the first annular space flow channel 23. The conical valve head 3 is connected downwardly to a valve stem 5. A second annular space flow channel 27 is provided between the valve stem 5 and the upper tube 1, and a first through hole 26 that connects the first annular space flow channel 23 and the second annular space flow channel 27 is provided on the water injection valve stem 5.

[0048] A piston portion 29 is provided in the middle of the outer side of the valve stem 5, which is slidingly and sealingly matched with the inner wall of the first outer cylinder 2. A sliding seat 4 and a fixed seat 6 are respectively provided on the upper and lower sides of the piston portion 29 in the cavity of the first outer cylinder 2. The sliding seat 4 and the fixed seat 6 respectively cooperate with the piston portion 29 to form an upper pressure chamber 28 and a lower pressure chamber 30 that drive the piston portion 29 to move up and down.

[0049] A third channel 31 and a fourth channel 32 are provided on the fixed seat 6. The third channel 31 is connected to the first channel 34. The fourth channel 32 is connected to the second channel 35 through the pressure transmission tube 33. The wall of the first outer cylinder 2 is provided with a pressure injection channel 24 connected to the upper pressure chamber 28 and the fourth channel 32, and an upper water injection channel 7 connecting the lower pressure chamber 30 with the first channel 34.

[0050] The oil-water valve includes a second outer cylinder 9, the top of which is connected to the outer peripheral side of the bottom of the bridge joint 8, and the bottom of the second outer cylinder 9 is connected to a bridge joint 19, on the wall of which an internal oil production channel 45 and an external water injection channel 20 are provided.

[0051] An oil-water pipe 13 is coaxially provided in the second outer cylinder 9, and an oil hole 54 is provided in the middle of the oil-water pipe 13. The lower outer side of the oil-water pipe 13 is slidingly and sealingly connected to the oil-water valve sleeve 15. A coaxially arranged valve core 40 is provided in the oil-water valve sleeve 15. The bottom of the oil-water pipe 13 is provided with a conical second sealing surface 39 that cooperates with the head of the valve core 40. A second through hole 56 is provided on the wall of the valve core 40. The lower part of the inner cavity of the oil-water valve sleeve 15 is slidingly and sealingly connected to the lower pipe 44. The lower end of the outer wall of the lower pipe 44 is connected to the inner wall of the bridge joint 19.

[0052] The second outer cylinder 9 is provided with a pressure transmission seat 11, a piston cylinder 14 and a piston sleeve 17 from top to bottom in sequence, and an upper step 37 and a lower step 42 are provided in the second outer cylinder 9, and an upper flow channel 12 and a lower flow channel 16 are opened on the upper step 37 and the lower step 42. The lower flow channel 16 is connected with the external water injection channel 20, and the bottom of the piston sleeve 17 is installed in the top inner cavity of the bridge joint 19, and the middle part of the piston sleeve 17 is provided with an annular boss 43 that contacts and seals with the lower step 42. An annular gap flow channel 18 is provided between the piston sleeve 17 and the lower tube 44, and a third sealing surface 41 is provided on the top of the piston sleeve 17 and the bottom of the oil-water valve sleeve 15 for cooperating with each other to switch the gap flow channel 18. When the gap flow channel 18 is opened, the head of the valve core 40 cooperates with the second sealing surface 39 to close the bottom channel of the oil-water pipe 13. When the gap flow channel 18 is closed, the valve core 40 descends to open the bottom channel of the oil-water pipe 13.

[0053] The lower end of the piston cylinder 14 is slidably connected in the annular space between the lower step portion 42 and the upper end of the piston sleeve 17, and a lower piston chamber 52 is formed between the bottom of the piston cylinder 14 and the annular boss 43. The annular boss 43 is provided with a well pressure channel 53 that connects the lower piston chamber 52 with the external water injection channel 20, and the cylinder wall of the piston cylinder 14 is provided with an oil flow channel 55 that connects the oil hole 54 and the gap flow channel 18.

[0054] The upper end of the piston cylinder 14 is slidably connected in the annulus between the upper step 37 and the oil-water pipe 13. The pressure transmission seat 11 is installed between the upper step 37 and the oil-water pipe 13, and an upper piston cavity 38 for driving the piston cylinder 14 is formed between the pressure transmission seat 11 and the piston cylinder 14. The pressure transmission seat 11 is provided with a pressure transmission channel 36 connecting the second channel 35 with the piston cavity, and a flow groove 10 connecting the first channel 34 with the upper flow channel 12 below. Example 2

[0055] This embodiment is further optimized based on the above embodiment, specifically:

[0056] The bottom of the lower tube 44 is connected downwardly to a water intake pipe 47, and the inner peripheral side of the bridge joint 19 is connected downwardly to an oil intake pipe 48. An annular oil intake channel 22 is formed between the oil intake pipe 48 and the water intake pipe 47. The oil intake channel 22 is connected to the gap flow channel 18 through the internal oil production channel 45 of the bridge joint 19.

[0057] A compensation pipe 46 is downwardly connected to the outer peripheral side of the bridge joint 19 , and an annular space reinjection channel 21 is formed between the compensation pipe 46 and the oil extraction pipe 48 . Example 3

[0058] like Figure 5 This embodiment adopts the same-well injection and production process method of the oil-water valve-controlled injection and production string in the above embodiment.

[0059] The process specifically comprises the following steps:

[0060] First, the inlet of the injection pump 57 is connected to the upper pipe 1 as a combined pipeline of the water intake pipeline and the oil intake pipeline. The top of the piston sleeve 17 contacts the third sealing surface 41 at the bottom of the oil-water valve sleeve 15 to form an oil intake valve 51, and the head of the valve core 40 contacts the second sealing surface 39 at the bottom of the oil-water pipe 13 to form a water intake valve 50.

[0061] Then, the outlet end of the injection pump 57 is divided into two paths, one of which is connected to the production pipeline pumped out of the ground, and a production valve 58 is installed on the production pipeline, and the other is connected to the first annular space flow channel 23 as a reinjection pipeline pumped into the well, and the conical valve head 3 and the first sealing surface 25 are combined to form a reinjection valve 49.

[0062] like Figure 1 and Figure 2 During the water injection operation: hydraulic pressure is injected into the injection channel 24, and a part of the hydraulic pressure enters the upper pressure chamber 28 to push the piston part 29 to drive the valve stem 5 and the conical valve head 3 downward, so that the conical valve head 3 is separated from the first sealing surface 25, thereby opening the back-injection valve 49, and the other part of the hydraulic pressure enters the upper piston chamber 38 through the fourth channel 32, the pressure transmission pipe 33, the second channel 35, and the pressure transmission channel 36, pushing the piston cylinder 14 to drive the oil-water valve sleeve 15 and the valve core 40 downward, so that the head of the valve core 40 is separated from the second sealing surface 39, thereby opening the water intake valve 50, and at the same time making the top of the piston sleeve 17 contact and cooperate with the bottom of the oil-water valve sleeve 15, closing the oil intake valve 51.

[0063] Downhole water enters the oil-water pipe 13 through the lower pipe 44, the inner cavity of the valve core 40, and the second through hole 56, and then enters the injection pump 57 through the inner cavity of the bridge joint 8 and the upper pipe 1, and is then re-injected into the downhole water injection layer by the injection pump 57 through the first annular space flow channel 23, the first through hole 26, the second annular space flow channel 27, the first channel 34, the upper flow channel 12, the lower flow channel 16, and the external water injection channel 20.

[0064] like Figure 3 and Figure 4 During oil production operations: the production valve 58 is opened, and the injection of hydraulic pressure into the injection and pressure channel 24 is stopped. The well pressure enters the lower piston chamber 52 through the external water injection channel 20 and the well pressure channel 53, pushing the piston cylinder 14 to drive the oil-water valve sleeve 15 and the valve core 40 upward, so that the head of the valve core 40 contacts the second sealing surface 39, thereby closing the water intake valve 50 and separating the top of the piston sleeve 17 from the bottom of the oil-water valve sleeve 15, opening the oil intake valve 51.

[0065] The well pressure also enters the lower pressure chamber 30 through the external water injection channel 20, the lower flow channel 16, the upper flow channel 12, the first channel 34, and the upper water injection channel 7, thereby pushing the piston part 29 to drive the valve stem 5 and the conical valve head 3 upward, so that the conical valve head 3 contacts and cooperates with the first sealing surface 25, thereby closing the re-injection valve 49.

[0066] The oil in the well enters the oil-water pipe 13 cavity through the internal oil production channel 45, the gap flow channel 18, the oil flow channel 55, and the oil hole 54, and then enters the injection pump 57 through the inner cavity of the bridge joint 8 and the inner cavity of the upper pipe 1. The injection pump 57 pumps the oil to the ground through the production pipeline.

[0067] Through the design of this tubing string, the re-injection valve 49, the oil extraction valve 51 and the water extraction valve 50 can be opened and closed. When the re-injection valve 49 is opened, the water extraction valve 50 can be opened in conjunction with it, and when the water extraction valve 50 is opened, the oil extraction valve 51 can be closed in conjunction with it, making the switching between oil production and water extraction and injection operations more convenient and flexible, laying the foundation for realizing the same-well injection and production technology.

[0068] This process method can adopt a single pump operation structure with high stability. The single pump is matched with a set of oil production pipelines and a set of separation water reinjection pipelines. The oil production operation and water injection operation can be switched at will according to the operation needs. It is very flexible and convenient. More importantly, the use of a single pump in the same well to drive the pump has much lower requirements than a single machine to drive two pumps. Therefore, the production and maintenance costs are also much lower. This is also the main reason for the large-scale promotion.

[0069] The present invention is not limited to the above-mentioned embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. The contents after the changes still fall within the scope of protection of the present invention.

Claims

1. Oil and water valve control string, characterized by: It includes a water injection valve, a bridge joint and an oil-water valve connected in sequence from top to bottom, and a first channel and a second channel are opened on the upper wall of the bridge joint; The water injection valve includes a first outer cylinder, the bottom of the first outer cylinder is connected to the outer peripheral side of the top of the bridge joint, an upper tube is coaxially arranged in the cavity of the first outer cylinder, the bottom of the upper tube is connected to the inner peripheral side of the top of the bridge joint, and a first annular flow channel is formed between the first outer cylinder and the upper tube; A conical valve head is provided in the first annular flow channel and is connected to the outer side of the upper tube in a sliding sealing manner. The inner circumferential surface of the first outer cylinder is provided with a conical first sealing surface that cooperates with the conical valve head to open and close the first annular flow channel. The conical valve head is downwardly connected to a valve stem. A second annular flow channel is provided between the valve stem and the upper tube, and a first through hole is provided on the water injection valve stem to connect the first annular flow channel with the second annular flow channel. A piston portion is provided at the middle portion of the outer side of the valve stem and is slidably and sealingly matched with the inner wall of the first outer cylinder. A sliding seat and a fixed seat are respectively provided on the upper and lower sides of the piston portion in the cavity of the first outer cylinder. The sliding seat and the fixed seat cooperate with the piston portion to form an upper pressure chamber and a lower pressure chamber for driving the piston portion to move up and down. The fixing seat is provided with a third channel and a fourth channel, the third channel is connected to the first channel, and the fourth channel is connected to the second channel via a pressure transmission tube. The first outer cylinder wall is provided with a pressure injection channel connected to the upper pressure chamber and the fourth channel, and an upper water injection channel connected to the lower pressure chamber and the first channel. The oil-water valve includes a second outer cylinder, the top of which is connected to the outer peripheral side of the bottom of the bridge joint, the bottom of which is connected to a bridge joint, and the wall of the bridge joint is provided with an inner oil production channel and an outer water injection channel; An oil-water pipe is coaxially provided in the second outer cylinder, an oil hole is provided in the middle of the oil-water pipe, an oil-water valve sleeve is slidably and sealingly connected to the lower outer portion of the oil-water pipe, a valve core is coaxially arranged in the oil-water valve sleeve, a conical second sealing surface is provided at the bottom of the oil-water pipe to cooperate with the valve core head, a second through hole is provided on the wall of the valve core, a lower pipe is slidably and sealingly connected to the lower inner portion of the oil-water valve sleeve, and the lower end of the outer wall of the lower pipe is connected to the inner wall of the bridge joint; The second outer cylinder is provided with a pressure transmission seat, a piston cylinder and a piston sleeve from top to bottom in sequence, an upper step portion and a lower step portion are provided in the second outer cylinder, and an upper flow channel and a lower flow channel are opened on the upper step portion and the lower step portion, the lower flow channel is connected with the external water injection channel, the bottom of the piston sleeve is installed in the top inner cavity of the bridge joint, the middle part of the piston sleeve is provided with an annular boss which is in contact and sealed with the lower step portion, an annular gap flow channel is provided between the piston sleeve and the lower tube, the top of the piston sleeve and the bottom of the oil-water valve sleeve are provided with a third sealing surface which cooperates with each other to open and close the gap flow channel, when the gap flow channel is opened, the valve core head cooperates with the second sealing surface to close the bottom channel of the oil-water pipe, and when the gap flow channel is closed, the valve core moves downward to open the bottom channel of the oil-water pipe; The lower end of the piston cylinder is slidably connected to the annulus between the lower step portion and the upper end of the piston sleeve, and a lower piston chamber is formed between the bottom of the piston cylinder and the annular boss. A well pressure channel is provided on the annular boss to connect the lower piston chamber with the external water injection channel. An oil flow channel is opened on the wall of the piston cylinder to connect the oil hole and the gap flow channel. The upper end of the piston cylinder is slidably connected in the annulus between the upper step portion and the oil-water pipe. The pressure transmission seat is installed between the upper step portion and the oil-water pipe, and an upper piston cavity for driving the piston cylinder is formed between the pressure transmission seat and the piston cylinder. The pressure transmission seat is provided with a pressure transmission channel connecting the second channel with the piston cavity, and a flow groove connecting the first channel with the upper flow channel below.

2. The oil-water valve control string according to claim 1, characterized in that: The bottom of the lower pipe is downwardly connected with a water intake pipe.

3. The oil-water valve control string according to claim 2, characterized in that: An oil extraction pipe is downwardly connected to the inner peripheral side of the bridge joint, and an annular oil extraction channel is formed between the oil extraction pipe and the water extraction pipe. The oil extraction channel is connected to the gap flow channel through the inner oil extraction channel of the bridge joint.

4. The oil-water valve control string according to claim 3, characterized in that: A compensation pipe is downwardly connected to the outer peripheral side of the bridge joint, and an annular space reinjection channel is formed between the compensation pipe and the oil extraction pipe.

5. A same-well injection-production process, characterized by: An oil-water valve control string according to any one of claims 1 to 4 is used; The same-well injection-production process comprises the following steps: First, connect the inlet of the injection pump to the upper pipe to form a combined pipeline for the water and oil extraction pipelines. The top of the piston sleeve contacts the third sealing surface at the bottom of the oil-water valve sleeve to form an oil extraction valve, and the head of the valve core contacts the second sealing surface at the bottom of the oil-water pipe to form a water extraction valve. Then, the outlet end of the injection pump is divided into two paths. One path is connected to the production pipeline pumped out of the surface, and a production valve is installed on the production pipeline. The other path is connected to the first annular flow channel as a reinjection pipeline pumped into the well. The conical valve head and the first sealing surface cooperate to form a reinjection valve. During water injection operation: hydraulic pressure is injected into the injection channel. A part of the hydraulic pressure enters the upper pressure chamber, pushing the piston part to drive the valve stem and the conical valve head downward, so that the conical valve head is separated from the first sealing surface, thereby opening the return valve. The other part of the hydraulic pressure enters the piston chamber through the fourth channel, the pressure transmission pipe, the second channel, and the pressure transmission channel, pushing the piston cylinder to drive the oil-water valve sleeve and the valve core downward, so that the valve core head is separated from the second sealing surface, thereby opening the water intake valve and making the top of the piston sleeve contact and cooperate with the bottom of the oil-water valve sleeve to close the oil intake valve. Downhole water enters the oil-water pipe through the lower pipe, the inner cavity of the valve core, and the second through hole, and then enters the injection pump through the inner cavity of the bridge joint and the upper pipe. The injection pump then injects water back into the downhole water injection layer through the first annular flow channel, the first through hole, the first channel, the upper flow channel, the lower flow channel, and the external water injection channel; During oil production operation: open the production valve and stop injecting hydraulic pressure into the injection and pressure channel. The well pressure enters the lower piston chamber through the external water injection channel and the well pressure channel, pushing the piston cylinder to drive the oil-water valve sleeve and the valve core upward, so that the head of the valve core contacts the second sealing surface, thereby closing the water intake valve and separating the top of the piston sleeve from the bottom of the oil-water valve sleeve, opening the oil intake valve; The well pressure also enters the lower pressure chamber through the lower flow channel of the external water injection channel, the upper flow channel, the first channel, and the upper water injection channel, thereby pushing the piston to drive the valve stem and the conical valve head upward, so that the conical valve head contacts and cooperates with the first sealing surface, thereby closing the re-injection valve; The oil in the well enters the oil-water pipe cavity through the internal oil production channel, gap flow channel, oil flow channel, and oil hole, and then enters the injection pump through the inner cavity of the bridge joint and the inner cavity of the upper pipe. The injection pump pumps the oil to the ground through the production pipeline.

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