Downhole two-stage safety control and production integrated string and method

Abstract

This invention relates to the field of oil extraction technology, and particularly to a downhole dual-stage safety control and production integrated tubing string and method. The technical solution is as follows: A plug, three safety production valves, three packers, a sliding sleeve, and a landing section are connected and mounted at the wellhead via tubing, forming an oil-bearing section production safety control system. Then, a second electric pump lifting system is run in parallel. First, an electric pump and a check valve are run through the annulus, and a cable is connected to the upper part of the electric pump. The lower part of the Y-connector is connected to the tubing and the upper part to the cable packer. Cables and control cables pass through the cable packer. Tubing and a downhole safety valve are connected to the main channel of the cable packer, and a second pipeline connects to the vent valve. The beneficial effects are: This invention, through a two-stage safety control system, not only meets the production needs of oil and gas wells in medium and deep water areas, but also improves the reliability of downhole safety production and avoids the failure of the entire downhole safety control system.

Description

Technical Field

[0001] This invention relates to the field of oil extraction technology, and in particular to a downhole dual-stage safety control and production integrated tubing string and method. Background Technology

[0002] Currently, offshore oil and gas extraction is the main force for increasing oil and gas reserves and production in my country. Based on the differences in water depth in the operating sea area, the main extraction methods and facilities can be divided into shallow water areas (such as shallower than 12 meters), medium water depth areas, and deep water areas. In shallow water areas, artificial islands are usually built, followed by drilling and laying of subsea pipelines. In medium water depth areas, fixed oil production platforms are mainly built, on which multiple vertical or deviated wells can be drilled to control a larger oil reservoir area. In deep water areas, floating oil production platforms (such as semi-submersible platforms and tension leg platforms) are widely used. The extracted oil and gas are positioned by mooring systems and transported via subsea pipelines or tankers.

[0003] However, existing mid- and deep-water oil and gas fields are characterized by harsh environments and complex reservoir and well conditions, resulting in high extraction risks; any incident could be a major disaster. To ensure the safe and efficient development of offshore oil and gas wells, downhole safety control systems must be installed below 30 meters from the seabed. In the event of an accident such as a fire or pipeline leak on the platform, the downhole safety valve can be controlled from the platform or a remote control panel to close the tubing annulus and the casing annulus via a cable packer, thus shutting down the wellbore and preventing oil and gas leaks. In addition, to meet the requirements of backwashing during production and sealing through cables and capillary tubes, the cable packer is equipped with tools such as cable seals and vent valves. If any of these tools fails, the entire downhole safety control system will fail.

[0004] Therefore, in order to further improve the safe development of oil and gas wells in the mid-deep sea area, a downhole two-level safety control and production integrated tubing system and method are proposed. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned deficiencies in existing technologies by providing a downhole dual-level safety control and production integrated tubing string and method. This method enables both stratified oil production in medium and deep water oil and gas wells and dual-level downhole safety control of the oil layer and the upper part of the wellbore, thereby improving the reliability of the downhole safety control system for medium and deep water oil and gas wells and preventing the failure of the entire downhole safety control system.

[0006] The present invention discloses a downhole dual-stage safety control and production integrated tubing string, including tubing, and further including a downhole safety valve, cable, cable packer, second pipeline, vent valve, Y-joint, check valve, electric pump, landing sub, control cable, sliding sleeve, first packer, first safety production valve, and plug. The plug, first safety production valve, first packer, sliding sleeve, and landing sub are connected and mounted at the wellhead in sequence from bottom to top through the tubing to form an oil layer production safety control system. The first safety production valve is equipped with a permanent magnet and a safety production valve sliding sleeve. The safety production valve sliding sleeve is provided with a flow channel. When continuously energized, the safety production valve sliding sleeve is away from the permanent magnet and is in an open fluid flow state. When an accident occurs and the power is cut off, the safety production valve sliding sleeve resets and is in a closed protection state. Next, another electric pump lifting system is lowered in parallel. First, the electric pump and check valve are lowered into the annulus between the tubing and casing, and a cable is connected to the upper part of the electric pump. Then, the tubing located above the short section and the tubing above the check valve are connected to the two lower connection ports of the Y-type joint. The upper part of the Y-type joint is connected to the tubing and the cable packer. The cable and the control cable pass through the cable packer respectively. The cable is sealed with the cable packer by a cable sealing tool. The control cable passes through the cable packer and is connected to the ground control system. Connect the tubing and downhole safety valve to the main channel of the cable packer, connect the second pipeline to the vent valve, and after the downhole safety valve passes the pressure test, lower the entire tubing string into the designed position inside the casing through the tubing. The first safety production valve includes an upper connector, a safety production valve cable, an outer pipe, a central pipe, a permanent magnet, an electromagnetic coil, a retaining ring, a safety production valve sleeve, a spring, and a lower connector. The outer pipe is provided at the outer end of the central pipe. One end of the central pipe and the outer pipe are connected to the upper connector, and the other end is connected to the lower connector. A permanent magnet is installed in the annular space between the central pipe and the outer pipe through the retaining ring. A safety production valve sleeve is installed on the outer ring of the permanent magnet. An electromagnetic coil is wound around the upper outer ring of the safety production valve sleeve and is connected to the wellhead on the ground through the safety production valve cable. A flow channel is provided at the lower part of the safety production valve sleeve. An inner liquid passage hole is provided on the middle and lower side of the central pipe, and an outer liquid passage hole is provided on the middle and lower side of the outer pipe. A spring is installed at the lower part of the safety production valve sleeve.

[0007] Preferably, the Y-type connector has two lower connection ports at the bottom, which are respectively connected to the central oil pipe and the outlet above the check valve, and an upper connection port at the top of the Y-type connector, which is connected to the upper oil pipe, so that the two systems can be brought together through the Y-type connector.

[0008] Preferably, the first safety production valve is connected to a second packer, a second safety production valve, a third packer, and a third safety production valve below it, so as to realize the independent mining of the three oil layers, or the combined mining of two layers or all three layers. The first safety production valve, the second safety production valve, and the third safety production valve are all electrically driven and are respectively connected to control cables.

[0009] Preferably, the aforementioned cable packer has cable passage holes on both sides, allowing a cable to pass through on one side and be sealed to the cable packer by a cable sealing tool, and a control cable to pass through on the other side and be sealed to the cable packer. The lower part of the control cable passes through the first packer and connects to the first safety production valve, passes through the second packer and connects to the second safety production valve, and passes through the third packer and connects to the third safety production valve. The upper end of the control cable is connected to the surface control system. In addition, an vent valve is connected to the side flow channel of the cable packer, allowing the annulus between the tubing and the casing to be connected to the surface wellhead through the vent valve and the second pipeline.

[0010] Preferably, the aforementioned short section is located above the sliding sleeve, and the inner wall of the short section is provided with a liquid passage. By inserting a plug and placing it in the liquid passage, the liquid passage can be opened and closed.

[0011] Preferably, the aforementioned sliding sleeve is connected to the oil pipe above the first packer. By inserting a steel wire into the ground, the sliding sleeve is opened, thereby allowing the liquid in the oil pipe to communicate with the inner cavity of the casing.

[0012] Preferably, the downhole safety valve adopts a hydraulic structure. The upper part of the downhole safety valve is connected to the surface control system through a first pipeline. The surface control system controls the opening and closing of the downhole safety valve by actively pressurizing or depressurizing. In the event of a major accident such as a fire or pipeline leak at the platform wellhead, the downhole safety valve is triggered to close the space inside the tubing.

[0013] The method for using the integrated downhole dual-level safety control and production tubing mentioned in this invention includes the following process: (1) Insertion of tubing: First, an oil production safety control system is run along the casing at the wellhead on the offshore platform. From bottom to top, the plug, third safety production valve, third packer, second safety production valve, second packer, first safety production valve, first packer, sliding sleeve, and landing sub are connected and mounted at the wellhead via tubing. Then, another electric pump lifting system is run in parallel. The electric pump is first run into the annulus between the tubing and casing. A check valve and cable are connected to the electric pump, and it is connected via tubing to a lower connection port at the lower end of a Y-joint. The upper end of the landing sub... The tubing connects to another lower connection port at the lower end of the Y-type connector. The upper part of the Y-type connector connects the tubing and the cable packer. The cable and control cable pass through the cable packer respectively. The cable is sealed to the cable packer by a cable sealing tool. The control cable passes through the cable packer and connects to the surface control system. The tubing and downhole safety valve are connected to the main channel of the cable packer. The second pipeline is connected to the vent valve. After the downhole safety valve passes the pressure test, the entire tubing string is lowered into the designed position inside the casing through the tubing. (2) Packer setting, sealing, and delamination: The oil pipe passage of the oil layer section stratified oil production safety control system is closed by the first, second, and third safety production valves. The electric pump lifting system is closed by the check valve. The oil pipe is pressurized to the design value. The first, second, and third packers and the cable packer are set. The first packer and the cable packer form two oil casing seals. The second and third packers divide the entire oil layer section into three oil layers, which can be independently controlled by the corresponding safety production valves. When the control is energized, the safety production valve sleeves of the first, second, and third safety production valves are away from the permanent magnet and are in the open liquid-flow state. In the event of an accident and power failure, the corresponding safety production valve sleeves are reset and in the closed protection state. (3) Layered segmented production control: At the wellhead of the offshore platform, a steel wire is lowered along the tubing. The sliding sleeve is opened first through the steel wire operation, then the plug is inserted and fixed to the short section. Finally, the first, second, and third safety production valves corresponding to the three oil layers are connected through the control cable to realize the independent production of the three oil layers, or the combined production of two or three layers. The oil and gas fluid enters the tubing, flows through the first packer and the sliding sleeve, and flows along the side hole of the sliding sleeve to the annulus of the tubing and casing above the first packer. It is then pressurized and lifted by the electric pump in the electric pump lifting system, and enters the tubing connected above the Y-joint through the check valve and Y-joint. It then flows through the cable packer and downhole safety valve to be extracted to the surface. (4) Downhole two-level safety control: In the event of a major accident such as a fire or pipeline leak at the wellhead of an offshore platform, the downhole safety valve is triggered, closing the space inside the tubing and sealing the annulus via the cable packer, thereby closing the upper wellbore and achieving the first level of downhole safety control. Simultaneously, the first, second, and third packers seal the annulus of the three oil layers, and the first, second, and third safety production valves close, forming the second level of safety control system for the oil layer section, achieving two-level safety control for the flow of formation fluids out of the wellbore.

[0014] Preferably, the present invention further includes a reverse circulation well washing process as follows: First, the vent valve is opened via the second pipeline control. Then, a steel wire is lowered along the tubing at the wellhead on the offshore platform, and the plug is retrieved using the steel wire. Next, the reverse circulation well-washing fluid is injected from the wellhead on the offshore platform along the annulus, passes through the vent valve and the side flow channel on the cable packer, and enters the annulus between the cable packer and the first packer. The reverse circulation well-washing fluid then flows into the tubing cavity through the side hole of the sliding sleeve, and then flows through the landing sub and the Y-joint. Because the other lower connection port of the Y-joint is blocked by a check valve, the reverse circulation well-washing fluid can only continue to flow upward along the upper connection port of the Y-joint, through the main channel of the cable packer and the downhole safety valve, and then flow out of the surface along the tubing, thus realizing the reverse washing operation.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention establishes a first-level downhole safety control system for the upper part of the casing through downhole safety valves and cable packers. Then, through the first, second, and third packers, the oil layer section is sealed, achieving both annular sealing and layering of the oil layer. The first, second, and third safety production valves control whether oil fluid enters the tubing. Through these three levels of packing and safety production valves, independent control and a second-level safety control system are achieved in the oil layer section. Therefore, this two-level safety control system not only meets the production needs of oil and gas wells in medium and deep water areas but also improves the reliability of downhole safety production, preventing the failure of the entire downhole safety control system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the invention being lowered into the well; Figure 3 This is a schematic diagram of the setting of packers at various levels; Figure 4 This is a schematic diagram of segmented production; Figure 5 This is a schematic diagram of a two-level safety control system in the well. Figure 6This is a schematic diagram of reverse circulation well washing; Figure 7 This is a structural diagram of a safety production valve; Figure 8 This is a schematic diagram of the structure when the safety production valve is open; Figure 9 This is a schematic diagram of the structure when the safety production valve is closed; In the diagram: 1. Tubing; 2. First pipeline; 3. Downhole safety valve; 4. Cable; 5. Cable sealing tool; 6. Cable packer; 7. Second pipeline; 8. Vent valve; 9. Y-joint; 10. Check valve; 11. Electric pump; 12. Blocker; 13. Settling sub; 14. Control cable; 15. Sliding sleeve; 16. First packer; 17. First safety production valve; 18. Second packer; 19. Second safety production valve; 20. Third packer; 21. Plug; 22. Casing; 23. 17.1 Pressure cap, 17.2 Upper connector, 17.3 Safety production valve cable, 17.4 First sealing ring, 17.5 Outer tube, 17.6 Central tube, 17.7 Permanent magnet, 17.8 Electromagnetic coil, 17.9 Retaining ring, 17.10 Second sealing ring, 17.11 Safety production valve sliding sleeve, 17.12 Spring, 17.13 Lower connector, 17.14 Outer liquid passage, 17.15 Inner liquid passage, 17.16 Flow passage, N pole, S pole. Detailed Implementation

[0017] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0018] Example 1, referring to Figure 1The present invention mentions a downhole dual-stage safety control and production integrated tubing string, taking three independent oil layers as an example. It includes tubing 1, a downhole safety valve 3, a cable 4, a cable packer 6, a second pipeline 7, an air vent valve 8, a Y-connector 9, a check valve 10, an electric pump 11, a landing section 13, a control cable 14, a sliding sleeve 15, a first packer 16, a first safety production valve 17, a second packer 18, a second safety production valve 19, a third packer 20, a third safety production valve 21, and a plug 22. These components are connected sequentially from bottom to top: plug 22, third safety production valve 21, third packer 20, second safety valve 21, and third safety production valve 22. Production valve 19, second packer 18, first safety production valve 17, first packer 16, sliding sleeve 15 and landing section 13 are connected by tubing 1 and mounted at the wellhead to form an oil production safety control system for an oil layer section; a permanent magnet 17.7 and a safety production valve sliding sleeve 17.11 are installed inside the first safety production valve 17. The safety production valve sliding sleeve 17.11 is provided with a flow passage 17.16. When continuously energized, the safety production valve sliding sleeve 17.11 is away from the permanent magnet 17.7 and is in the open fluid flow state. When an accident occurs and the power is cut off, the safety production valve sliding sleeve 17.11 resets and is in the closed protection state; Next, another electric pump lifting system is lowered in parallel. First, electric pump 11 and check valve 10 are lowered into the annulus between oil pipe 1 and casing 23, and cable 4 is connected to the upper part of electric pump 11. Then, oil pipe 1 located above short section 13 and oil pipe 1 above check valve 10 are connected to the two lower connection ports of Y-type connector 9. The upper part of Y-type connector 9 is connected to oil pipe 1 and cable packer 6. Cable 4 and control cable 14 pass through cable packer 6 respectively. Cable 4 is sealed to cable packer 6 by cable sealing tool 5. Control cable 14 is connected to ground control system after passing through cable packer 6. Connect tubing 1 and downhole safety valve 3 to the main channel of the cable packer 6, connect the second pipeline 7 to the vent valve 8, and after the downhole safety valve 3 passes the pressure test, lower the entire tubing string into the designed position inside the casing 23 through tubing 1.

[0019] Reference Figures 7-9The first safety production valve 17 mentioned in this invention includes a pressure cap 17.1, an upper connector 17.2, a safety production valve cable 17.3, a first sealing ring 17.4, an outer tube 17.5, a central tube 17.6, a permanent magnet 17.7, an electromagnetic coil 17.8, a retaining ring 17.9, a second sealing ring 17.10, a safety production valve sliding sleeve 17.11, a spring 17.12, a lower connector 17.13, an outer liquid passage hole 17.14, an inner liquid passage hole 17.15, and a flow channel 17.16. The outer end of the central tube 17.6 is provided with an outer tube 17.5. One end of the central tube 17.6 and the outer tube 17.5 are connected to the upper connector 17.2, and the other end is connected to the lower connector 17.13. A permanent magnet 17.7 is installed in the annular space between the central tube 17.6 and the outer tube 17.5 through the retaining ring 17.9. The safety production valve is installed on the outer ring of the permanent magnet 17.7. The safety production valve slide sleeve 17.11 has an electromagnetic coil 17.8 wound around its upper outer ring and connected to the wellhead via a safety production valve cable 17.3. A flow passage 17.16 is provided at the lower part of the safety production valve slide sleeve 17.11. An inner fluid passage hole 17.15 is provided on the lower middle side of the central tube 17.6, and an outer fluid passage hole 17.14 is provided on the lower middle side of the outer tube 17.5. A spring 17.12 is installed at the lower part of the safety production valve slide sleeve 17.11. The safety production valve cable 17.3 passes through cable holes provided on the side walls of the upper connector 17.2 and the lower connector 17.13 and is sealed by pressure caps 17.1 respectively. Additionally, a first sealing ring 17.4 is installed between the central tube 17.6 and the upper connector 17.2, and multiple second sealing rings 17.10 are provided between the safety production valve slide sleeve 17.11 and the central tube 17.6.

[0020] Its working principle is: I. When the first safety production valve 17 is open, the oil production state is activated: the safety production valve cable 17.3 is energized, and the electromagnetic coil 17.8 generates electromagnetic and magnetic poles under the action of current, such as... Figure 7 The upper end of the electromagnetic coil 17.8 is the N pole, and the lower end is the S pole. The upper end of the installed permanent magnet 17.7 is also the N pole, and the lower end is the S pole. When the magnetic poles generated by the electromagnetic coil and the permanent magnet 17.7 are the same, they repel each other, pushing the safety production valve sleeve 17.11 downwards against the spring force of the spring 17.12. This achieves internal and external communication of the first safety production valve 17. The flow channel 17.16 is located between the external liquid passage 17.14 and the internal liquid passage 17.15, forming a liquid passage. The first safety production valve 17 is in the open state, allowing for oil extraction and production operations. Figure 8 As shown; II. When the first safety production valve 17 is closed, it is in a safe state: Under abnormal circumstances, the safety production valve cable 17.3 cannot be powered, and the electromagnetic coil 17.8 cannot generate magnetic force. At this time, the safety production valve sleeve 17.11 moves upward under the elastic force of the spring 17.12, closing the first safety production valve 17. Figure 9 As shown, the flow passage 17.16 is separated from the outer liquid passage hole 17.14 and the inner liquid passage hole 17.15, so that a liquid passage cannot be formed, and the first safety production valve 17 is in a safe closed state.

[0021] In addition, the second safety production valve 19 and the third safety production valve 21 have the same structure and operating principle as the first safety production valve 17, and will not be described further.

[0022] Furthermore, the Y-type connector 9 mentioned in this invention has two lower connection ports at its lower part, which are respectively connected to the central oil pipe 1 and the outlet above the check valve 10. An upper connection port is provided at the upper part of the Y-type connector 9, which is connected to the upper oil pipe 1, so that the two systems can be brought together through the Y-type connector 9.

[0023] In addition, the cable packer 6 mentioned in this invention has cable passage holes on both sides, allowing cable 4 to pass through on one side and be sealed with the cable packer 6 by the cable sealing tool 5, and control cable 14 to pass through on the other side and be sealed with the cable packer 6. The lower part of the control cable 14 passes through the first packer 16 and connects to the first safety production valve 17, passes through the second packer 18 and connects to the second safety production valve 19, passes through the third packer 20 and connects to the third safety production valve 21, and the upper end of the control cable 14 is connected to the ground control system.

[0024] The vent valve 8 mentioned in this invention is connected to the side flow channel of the cable packer 6, so that the annulus between the tubing 1 and the casing 23 is connected to the surface wellhead through the vent valve 8 and the second pipeline 7.

[0025] The short section 13 mentioned in this invention is located above the sliding sleeve 15, and the inner wall of the short section 13 is provided with a liquid passage. By inserting the plug 12 and placing it in the liquid passage, the liquid passage can be opened and closed.

[0026] The sliding sleeve 15 mentioned in this invention is connected to the oil pipe 1 above the first packer 16. By inserting a steel wire into the ground, the sliding sleeve 15 is opened, thereby allowing the liquid in the oil pipe 1 to communicate with the inner cavity of the casing 23.

[0027] The first safety production valve 17, the second safety production valve 19 and the third safety production valve 21 mentioned in this invention adopt an electrically driven structure and are respectively connected to the control cable 14.

[0028] The downhole safety valve 3 mentioned in this invention adopts a hydraulic structure. The upper part of the downhole safety valve 3 is connected to the surface control system through the first pipeline 2. The surface control system realizes the on / off control of the downhole safety valve 3 by actively pressurizing or depressurizing. In the event of a major accident such as fire or pipeline leakage at the wellhead of the offshore platform in medium and deep water areas, the downhole safety valve 3 is triggered to close the space inside the oil pipe 1.

[0029] Additionally, it should be noted that the downhole safety valve 3 and sliding sleeve 15 mentioned in this invention are existing technologies well known to those skilled in the art, therefore, their structures will not be described in detail here.

[0030] The method for using the integrated downhole dual-level safety control and production tubing mentioned in this invention includes the following process: (1) Insertion of tubing: Reference Figure 2 First, an oil production safety control system is lowered into the wellhead along the casing 23 on the offshore platform. From bottom to top, the plug 22, third safety production valve 21, third packer 20, second safety production valve 19, second packer 18, first safety production valve 17, first packer 16, sliding sleeve 15, and landing section 13 are connected and mounted at the wellhead via tubing 1. Then, another electric pump lifting system is lowered in parallel. The electric pump 11 is first lowered into the annulus between tubing 1 and casing 23. A check valve 10 and cable 4 are connected to the electric pump 11, and it is connected to a lower connection port at the lower end of the Y-connector 9 via tubing 1. The upper end of the short section 13 is connected to another lower connection port at the lower end of the Y-type connector 9 via tubing 1. The upper part of the Y-type connector 9 is connected to tubing 1 and cable packer 6. Cable 4 and control cable 14 pass through the cable packer 6 respectively. Cable 4 is sealed to the cable packer 6 by cable sealing tool 5. The control cable 14 passes through the cable packer 6 and is connected to the surface control system. Tubing 1 and downhole safety valve 3 are connected to the main channel of the cable packer 6. The second pipeline 7 is connected to the vent valve 8. After the downhole safety valve 3 passes the pressure test, the entire tubing string is lowered into the designed position inside the casing 23 via tubing 1. (2) Packer setting, sealing, and delamination: Reference Figure 3The oil pipe 1 of the oil layer section stratified oil production safety control system is closed by the first safety production valve 17, the second safety production valve 19 and the third safety production valve 21. The electric pump lifting system is closed by the check valve 10. The oil pipe 1 is pressurized to the design value. The first packer 16, the second packer 18, the third packer 20 and the cable packer 6 are set. The first packer 16 and the cable packer 6 form two oil casing seals. The second packer 18 and the third packer 20 divide the entire oil layer section into three oil layers, which facilitates independent control of the corresponding safety production valves. When the control is energized, the safety production valve sleeves 17.11 of the first safety production valve 17, the second safety production valve 19 and the third safety production valve 21 are away from the permanent magnet 17.7 and are in the open liquid flow state. When an accident occurs and the power is cut off, the corresponding safety production valve sleeves 17.11 are reset and in the closed protection state. (3) Layered segmented production control: Reference Figure 4 At the wellhead of the offshore platform, a steel wire is lowered along the tubing 1. The sliding sleeve 15 is opened first through the steel wire operation, and then the plug 12 is put in and fixed on the landing section 13. Finally, the first safety production valve 17, the second safety production valve 19 and the third safety production valve 21 corresponding to the three oil layers are connected through the control cable 14 to realize the independent production of the three oil layers, or the combined production of two layers or all three layers. The oil and gas fluid enters the tubing 1, flows through the first packer 16 and the sliding sleeve 15, flows along the side hole of the sliding sleeve 15 to the annulus of the tubing 1 and the casing 23 above the first packer 16, is pressurized and lifted by the electric pump 11 in the electric pump lifting system, and enters the tubing 1 connected above the Y-type connector 9 through the single-flow valve 10 and the Y-type connector 9. It then flows through the cable packer 6 and the downhole safety valve 3 and is extracted to the surface. (4) Downhole two-level safety control: Reference Figure 5 In the event of a major accident such as a fire or pipeline leak at the wellhead of the offshore platform, the downhole safety valve 3 is triggered, closing the space inside the tubing 1 and sealing the annulus through the cable packer 6, thereby closing the upper wellbore and achieving the first level of downhole safety control. At the same time, the first packer 16, the second packer 18, and the third packer 20 seal the annulus of the three oil layers, and the first safety production valve 17, the second safety production valve 19, and the third safety production valve 21 close, forming the second level of safety control system for the oil layer section, achieving two-level safety control for the formation fluid to flow out of the wellbore.

[0031] Example 2, the method of using the integrated downhole dual-level safety control and production tubing mentioned in this invention differs from Example 1 in that: This invention also includes a reverse circulation well washing process: Reference Figure 6First, the vent valve 8 is opened by controlling the second pipeline 7. Then, a steel wire is lowered into the tubing 1 at the wellhead of the offshore platform, and the plug 12 is retrieved by the steel wire operation. Then, the reverse circulation well-washing fluid is injected from the wellhead of the offshore platform along the annulus, passes through the vent valve 8 and the side flow channel on the cable packer 6, and enters the annulus between the cable packer 6 and the first packer 16. The reverse circulation well-washing fluid then flows into the inner cavity of the tubing 1 through the side hole of the sliding sleeve 15, and then flows through the short section 13 and the Y-joint 9. Since the other lower connection port of the Y-joint 9 is blocked by the check valve 10, the reverse circulation well-washing fluid can only continue to flow upward along the upper connection port of the Y-joint 9 through the main channel of the cable packer 6 and the downhole safety valve 3, and then flow out of the surface along the tubing 1, thus realizing the reverse well-washing operation.

[0032] The above description is merely a partial preferred embodiment of the present invention. Any person skilled in the art can modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, any simple modifications or equivalent transformations made based on the technical solutions of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A downhole two-stage safety control and production integrated string, comprising a tubing (1), characterized in that: It also includes a downhole safety valve (3), cable (4), cable packer (6), second pipeline (7), vent valve (8), Y-connector (9), check valve (10), electric pump (11), landing sub (13), control cable (14), sliding sleeve (15), first packer (16), first safety production valve (17), and plug (22). The plug (22), first safety production valve (17), first packer (16), sliding sleeve (15), and landing sub (13) are connected to the tubing from bottom to top. (1) Connect and hang at the wellhead to form an oil production safety control system for an oil layer section. The first safety production valve (17) is equipped with a permanent magnet (17.7) and a safety production valve sleeve (17.11). The safety production valve sleeve (17.11) is provided with a flow passage (17.16). When the power is continuously supplied, the safety production valve sleeve (17.11) is away from the permanent magnet (17.7) and is in the open liquid supply state. When the power is cut off due to an accident, the safety production valve sleeve (17.11) is reset and is in the closed protection state. Then, another electric pump lifting system is lowered in parallel. First, the electric pump (11) and the check valve (10) are lowered into the annulus between the oil pipe (1) and the casing (23), and the cable (4) is connected to the upper part of the electric pump (11). Then, the oil pipe (1) located above the short section (13) and the oil pipe (1) above the check valve (10) are connected to the two lower connection ports of the Y-type connector (9). The upper part of the Y-type connector (9) is connected to the oil pipe (1) and the cable packer (6). The cable (4) and the control cable (14) pass through the cable packer (6) respectively. The cable (4) is sealed with the cable packer (6) by the cable sealing tool (5). The control cable (14) passes through the cable packer (6) and is connected to the ground control system. Connect the tubing (1) and the downhole safety valve (3) to the main channel of the cable packer (6), connect the second pipeline (7) to the vent valve (8), and after the downhole safety valve (3) passes the pressure test, lower the entire tubing string into the designed position inside the casing (23) through the tubing (1). The first safety production valve (17) includes an upper connector (17.2), a safety production valve cable (17.3), an outer tube (17.5), a central tube (17.6), a permanent magnet (17.7), an electromagnetic coil (17.8), a retaining ring (17.9), a safety production valve sliding sleeve (17.11), a spring (17.12), and a lower connector (17.13). The outer end of the central tube (17.6) is provided with an outer tube (17.5). One end of the central tube (17.6) and the outer tube (17.5) are connected to the upper connector (17.2), and the other end is connected to the lower connector (17.13). The annular space between the central tube (17.6) and the outer tube (17.5) is filled with a cable. A permanent magnet (17.7) is installed on the retaining ring (17.9). A safety production valve sleeve (17.11) is installed on the outer ring of the permanent magnet (17.7). An electromagnetic coil (17.8) is wound on the upper outer ring of the safety production valve sleeve (17.11) and connected to the wellhead on the ground through a safety production valve cable (17.3). A flow passage (17.16) is provided at the lower part of the safety production valve sleeve (17.11). An inner liquid passage hole (17.15) is provided on the middle and lower side of the central tube (17.6), and an outer liquid passage hole (17.14) is provided on the middle and lower side of the outer tube (17.5). A spring (17.12) is installed at the lower part of the safety production valve sleeve (17.11).

2. The downhole two-stage safety control and production integrated string of claim 1, characterized by: The Y-type connector (9) has two lower connection ports at the bottom, which are connected to the central oil pipe (1) and the outlet above the flow valve (10) respectively. The Y-type connector (9) has an upper connection port at the top, which is connected to the upper oil pipe (1), so that the two systems can be brought together through the Y-type connector (9).

3. The downhole two-stage safety control and production integrated string of claim 2, characterized by: The first safety production valve (17) is connected to the second packer (18), the second safety production valve (19), the third packer (20), and the third safety production valve (21) to realize the independent mining of the three oil layers, or the combination of two layers, or the joint mining of the three layers together. The first safety production valve (17), the second safety production valve (19), and the third safety production valve (21) are all electrically driven and are respectively connected to the control cable (14).

4. The integrated downhole dual-stage safety control and production string according to claim 3, characterized in that: The cable pass-through packer (6) has cable passing holes on both sides, allowing the cable (4) to pass through on one side and be sealed with the cable pass-through packer (6) by the cable sealing tool (5), and the control cable (14) to pass through on the other side and be sealed with the cable pass-through packer (6). The lower part of the control cable (14) passes through the first packer (16) and connects to the first safety production valve (17), passes through the second packer (18) and connects to the second safety production valve (19), passes through the third packer (20) and connects to the third safety production valve (21). The upper end of the control cable (14) is connected to the surface control system. In addition, the vent valve (8) is connected to the side flow channel of the cable pass-through packer (6), so that the annulus between the tubing (1) and the casing (23) is connected to the surface wellhead through the vent valve (8) and the second pipeline (7).

5. The integrated downhole dual-stage safety control and production string according to claim 4, characterized in that: The landing section (13) is located above the sliding sleeve (15), and the inner wall of the landing section (13) is provided with a liquid passage. By inserting a plug (12) into the liquid passage, the liquid passage can be opened and closed.

6. The integrated downhole dual-stage safety control and production string according to claim 5, characterized in that: The sliding sleeve (15) is connected to the oil pipe (1) above the first packer (16). By inserting a steel wire into the ground, the sliding sleeve (15) is opened, thereby allowing the liquid in the oil pipe (1) to communicate with the inner cavity of the casing (23).

7. The integrated downhole dual-stage safety control and production string according to claim 6, characterized in that: The downhole safety valve (3) adopts a hydraulic structure. The upper part of the downhole safety valve (3) is connected to the surface control system through the first pipeline (2). The surface control system controls the opening and closing of the downhole safety valve (3) by actively pressurizing or depressurizing. In the event of a fire or a major accident at the wellhead of the platform or a leak in the subsea pipeline, the downhole safety valve (3) is triggered to close the space inside the tubing (1).

8. The method of using the integrated downhole dual-level safety control and production tubing string according to claim 7, characterized in that: The process includes the following: (1) Insertion of tubing: First, an oil production safety control system is lowered into the wellhead along the casing (23) on the offshore platform. From bottom to top, the plug (22), third safety production valve (21), third packer (20), second safety production valve (19), second packer (18), first safety production valve (17), first packer (16), sliding sleeve (15), and landing sub (13) are connected and mounted at the wellhead via tubing (1). Then, another electric pump lifting system is lowered in parallel. The electric pump (11) is first lowered into the annulus between the tubing (1) and casing (23). A check valve (10) and a cable (4) are connected to the electric pump (11), and connected to a lower connection port at the lower end of a Y-connector (9) via tubing (1). The landing sub (15)... 3) The upper end is connected to another lower connection port of the Y-type connector (9) through the oil pipe (1). The upper part of the Y-type connector (9) is connected to the oil pipe (1) and the cable packer (6). The cable (4) and the control cable (14) pass through the cable packer (6) respectively. The cable (4) is sealed with the cable packer (6) through the cable sealing tool (5). The control cable (14) passes through the cable packer (6) and is connected to the ground control system. The oil pipe (1) and the downhole safety valve (3) are connected on the main channel of the cable packer (6). The second pipeline (7) is connected to the exhaust valve (8). After the downhole safety valve (3) passes the pressure test, the entire string is lowered into the designed position inside the casing (23) through the oil pipe (1). (2) Packer setting, sealing, and delamination: The oil pipe (1) of the oil layer section stratified oil production safety control system is closed by the first safety production valve (17), the second safety production valve (19), and the third safety production valve (21). The electric pump lifting system is shut off by the check valve (10). The oil pipe (1) is pressurized to the design value. The first packer (16), the second packer (18), the third packer (20), and the cable packer (6) are set. The first packer (16) and the cable packer (6) form two oil casing seals. The second packer (18) and the third packer (20) divide the entire oil layer into three oil layers, which facilitates independent control of the corresponding safety production valves. When the control is energized, the safety production valve sleeves (17.11) of the first safety production valve (17), the second safety production valve (19) and the third safety production valve (21) are away from the permanent magnet (17.7) and are in the open liquid flow state. When an accident occurs and the power is cut off, the corresponding safety production valve sleeves (17.11) are reset and are in the closed protection state. (3) Layered segmented production control: At the wellhead of the offshore platform, a steel wire is lowered along the tubing (1). The sliding sleeve (15) is opened using the steel wire, and then the plug (12) is inserted and fixed to the short section (13). Finally, the first safety production valve (17), the second safety production valve (19), and the third safety production valve (21) corresponding to the three oil layers are connected via the control cable (14). This enables independent production of the three oil layers, or combined production of two or all three layers, allowing for the flow of oil and gas. The oil enters the tubing (1), flows through the first packer (16) and the sliding sleeve (15), flows along the side hole of the sliding sleeve (15) to the annulus of the tubing (1) and casing (23) above the first packer (16), is pressurized and lifted by the electric pump (11) in the electric pump lifting system, passes through the check valve (10) and the Y-type connector (9) and then enters the tubing (1) connected above the Y-type connector (9), then flows through the cable packer (6) and the downhole safety valve (3) and is extracted to the surface; (4) Downhole two-level safety control: In the event of a fire or pipeline leak at the wellhead of the offshore platform, the downhole safety valve (3) is triggered to close the space inside the tubing (1) and the annulus is sealed by the cable packer (6), thereby closing the upper wellbore and achieving the first level of downhole safety control. At the same time, the first packer (16), the second packer (18) and the third packer (20) seal the annulus of the three oil layers, and the first safety production valve (17), the second safety production valve (19) and the third safety production valve (21) are closed, forming the second level of safety control system for the oil layer section, and achieving dual-level safety control for the formation fluid to flow out of the wellbore.

9. The method of using the integrated downhole dual-stage safety control and production tubing string according to claim 8, characterized in that: It also includes the following reverse circulation well washing process: First, the exhaust valve (8) is opened by controlling the second pipeline (7). Then, a steel wire is lowered into the tubing (1) at the wellhead of the offshore platform and the plug (12) is retrieved by the steel wire operation. Then, the reverse circulation well washing fluid is injected from the wellhead of the offshore platform along the annulus of the tubing and casing. It enters the annulus between the cable packer (6) and the first packer (16) through the exhaust valve (8) and the side flow channel on the cable packer (6). The reverse circulation well washing fluid then flows into the inner cavity of the tubing (1) through the side hole of the sliding sleeve (15), and then flows through the short section (13) and the Y-type joint (9). Since the other lower connection port of the Y-type joint (9) is blocked by the check valve (10), the reverse circulation well washing fluid can only continue to flow upward along the upper connection port of the Y-type joint (9) through the main channel of the cable packer (6) and the downhole safety valve (3), and then flow out of the surface along the tubing (1), thus realizing the reverse well washing operation.

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