A wellhead safety control system

Abstract

The embodiment of the present application provides a wellhead safety control system, which is used for improving the working efficiency and reliability of the wellhead safety control system. The control system comprises a high-pressure control system and a low-pressure control system. The high-pressure control system comprises a ground safety valve high-pressure control main circuit, a ground safety valve high-pressure control branch circuit, a downhole safety valve high-pressure control main circuit and a downhole safety valve high-pressure control branch circuit, and is used for providing high-pressure hydraulic pressure for the control system. The low-pressure control system comprises a fusible plug control branch circuit, a ground safety valve low-pressure control branch circuit and a downhole safety valve low-pressure control branch circuit, and is used for controlling the high-pressure control system to provide low-pressure hydraulic pressure.

Description

Technical Field

[0001] This application relates to the field of safety systems, and more particularly to a wellhead safety control system. Background Technology

[0002] The wellhead safety control panel (WHCP), also known as the wellhead safety valve control system, is mainly used to control the surface and downhole safety valves of oil and gas wells. It provides hydraulic power to the hydraulic actuators of the safety valves, thereby controlling the opening and closing of the safety valves. At the same time, the wellhead safety control panel also has functions such as emergency shutdown, remote shutdown, process shutdown, and fire shutdown.

[0003] As drilling depth increases, wellhead pressure rises accordingly, and the pressure of the corresponding wellhead safety control system also increases. Currently, the highest pressure level of traditional wellhead safety control systems is only 30,000 pounds per square inch (PSI). Meanwhile, wellhead products with pressure levels of 25,000 PSI and 30,000 PSI are already available on the market, meaning that a 30,000 PSI wellhead safety control system can no longer meet market demands. Furthermore, traditional wellhead safety control systems have several design flaws. For example, when the downhole safety valve control circuit depressurizes and closes the valve, the accumulator pressure is completely released, resulting in a slow shut-in speed. This slow shut-in speed poses a significant safety risk in the event of a wellhead fire. Additionally, restarting the well requires recharging the accumulator, leading to a slow start-up speed and low equipment efficiency. Traditional high-pressure wellhead safety control systems use solenoid valves for downhole safety valve operation, which cannot function properly when temporarily opening the well due to power outages, failing to meet on-site production needs. Traditional high-pressure wellhead safety control systems use electrical signal feedback and control in their fusible plug circuits. When the electrical signal is unstable, there is a risk of loss of control. Summary of the Invention

[0004] This application provides a wellhead safety control system to improve the working efficiency and reliability of the wellhead safety control system.

[0005] The first aspect of this application provides a wellhead safety control system, characterized in that the control system includes a high-pressure control system and a low-pressure control system;

[0006] The high-pressure control system includes a surface safety valve high-pressure control main circuit, a surface safety valve high-pressure control branch circuit, a downhole safety valve high-pressure control main circuit, and a downhole safety valve high-pressure control branch circuit, used to provide high-pressure hydraulic pressure to the control system. The input end of the surface safety valve high-pressure control main circuit is connected to the high-pressure control system, and its output end is connected to the input end of the surface safety valve high-pressure control branch circuit. The input end of the downhole safety valve high-pressure control main circuit is connected to the high-pressure control system, and its output end is connected to the input end of the downhole safety valve high-pressure control branch circuit. The output end of the surface safety valve high-pressure control branch circuit is connected to the surface safety valve, and the output end of the downhole safety valve high-pressure control branch circuit is connected to the downhole safety valve.

[0007] The low-pressure control system includes a fusible plug control branch, a surface safety valve low-pressure control branch, and a downhole safety valve low-pressure control branch, used to control the high-pressure control system to provide low-pressure hydraulic pressure. The input end of the fusible plug control branch is connected to the low-pressure control system, and is connected to the surface safety valve high-pressure control main line and the downhole safety valve high-pressure control main line respectively through the surface safety valve low-pressure control branch and the downhole safety valve low-pressure control branch, and its output end is connected to the fusible plug. The output end of the downhole safety valve low-pressure control branch is connected to the input end of the surface safety valve low-pressure control branch.

[0008] Optionally, the high-pressure control system further includes an oil tank, a filter, a ball valve, a control pump, and a check valve connected in series.

[0009] The filter includes a first filter and a second filter installed in parallel; the ball valve includes a first ball valve and a second ball valve installed in parallel; the control pump includes a first manual pump, a first electric pump, a second electric pump, and a second manual pump; the check valve includes a first check valve, a second check valve, a third check valve, and a fourth check valve.

[0010] The first ball valve is connected to the output end of the second electric pump and the output end of the second manual pump, which are connected in parallel. The second ball valve is connected to the output end of the first electric pump and the output end of the first manual pump, which are connected in parallel. It is used to shut down the circuit of the control system when the control system is under maintenance.

[0011] The output end of the first manual pump is connected to the input end of the first check valve, and the output end of the first check valve is connected to the input end of the low-pressure control system and the input end of the high-pressure control main circuit of the ground safety valve, respectively.

[0012] The output end of the first electric pump is connected to the input end of the second check valve, and the output end of the second check valve is connected to the input end of the low-pressure control system and the input end of the high-pressure control main circuit of the ground safety valve, respectively.

[0013] The output end of the second electric pump is connected to the input end of the third check valve, and the output end of the third check valve is connected to the input end of the high-pressure control main circuit of the downhole safety valve.

[0014] The output end of the second manual pump is connected to the input end of the fourth one-way valve, and the output end of the fourth one-way valve is connected to the input end of the high-pressure control main circuit of the downhole safety valve.

[0015] Optionally, the high-pressure control main circuit of the ground safety valve includes a second accumulator, the output end of which is connected to the high-pressure control main circuit of the ground safety valve to store hydraulic pressure in order to maintain the pressure of the control system.

[0016] Optionally, the high-pressure control main circuit of the ground safety valve further includes a second unloading valve, a second isolation valve, a first pressure transmitter, a first pressure gauge, a fifth check valve, and a first hydraulic valve, which are connected in sequence to the second accumulator.

[0017] The second unloading valve is connected to the pipeline between the output end of the second accumulator and the input end of the second isolation valve, and is used to release the high pressure hydraulic pressure of the second accumulator;

[0018] The output of the second isolation valve is connected to the high-pressure control main circuit of the ground safety valve, which is used to isolate the second accumulator from the control system;

[0019] The first hydraulic valve is connected to the output end of the high-pressure control main circuit of the ground safety valve, the input end of the high-pressure control branch circuit of the ground safety valve, and the output end of the low-pressure control branch circuit of the ground safety valve, so that the low-pressure control system controls the high-pressure hydraulic pressure of the high-pressure control system through the first hydraulic valve.

[0020] Optionally, the high-pressure control branch of the ground safety valve includes a second pressure transmitter, a second pressure gauge, a first shielded valve, and a quick-release valve connected in sequence.

[0021] The second pressure transmitter is connected to the output terminal of the high-pressure control main circuit of the ground safety valve and the output terminal of the low-pressure control branch circuit of the ground safety valve, respectively.

[0022] The first shielding valve is used to isolate the control system from the ground safety valve so as to keep the ground safety valve open when the high-voltage control system is under maintenance;

[0023] One end of the quick-release valve is connected to the first shielded valve, and the other end is connected to the ground safety valve; the quick-release valve also includes a vent for releasing high-pressure hydraulic pressure.

[0024] Optionally, the downhole safety valve high-pressure control main circuit includes a third accumulator and a fourth accumulator;

[0025] The output terminals of the third accumulator and the fourth accumulator are connected to the high-pressure control main circuit of the downhole safety valve to store hydraulic pressure in order to maintain the pressure of the control system.

[0026] The downhole safety valve high-pressure control main circuit also includes a first branch circuit and a second branch circuit; wherein, the first branch circuit is equipped with an electric pump, and the output end of the third accumulator is connected to the first branch circuit; the output ends of the first branch circuit and the second branch circuit are both connected to the downhole safety valve high-pressure control main circuit.

[0027] Optionally,

[0028] The first branch also includes a third unloading valve, a third shielding valve, a third pressure transmitter, a third pressure gauge, a booster pump, and a sixth check valve, which are connected in sequence to the third accumulator.

[0029] The third unloading valve is connected to the pipeline between the output end of the third accumulator and the input end of the third shielded valve, and is used to release the high-pressure hydraulic pressure of the third accumulator.

[0030] The output end of the third shielding valve is connected to the first branch, which is used to isolate the third accumulator from the control system;

[0031] The input end of the booster pump is connected to the output end of the third shielded valve, and the output end is connected to one end of the sixth check valve, which is used to boost the high pressure hydraulic pressure of the first branch to the target working pressure.

[0032] The other end of the sixth check valve is connected to the high-pressure control main circuit of the downhole safety valve, and is used to prevent the backflow of liquid in the high-pressure control main circuit of the downhole safety valve.

[0033] Optionally, the downhole safety valve high-pressure control main circuit further includes a fourth unloading valve, a fourth shielding valve, and a second hydraulic valve connected in sequence to the fourth accumulator;

[0034] The fourth unloading valve is connected to the pipeline between the output end of the fourth accumulator and the input end of the fourth shielded valve, and is used to release the high pressure hydraulic pressure of the fourth accumulator.

[0035] The output end of the fourth shielding valve is connected to the high-pressure control main circuit of the ground safety valve, which is used to isolate the fourth accumulator from the control system.

[0036] The second hydraulic valve is connected to the output end of the high-pressure control main circuit of the downhole safety valve, the input end of the high-pressure control branch circuit of the downhole safety valve, and the output end of the low-pressure control branch circuit of the downhole safety valve, so that the low-pressure control system controls the high-pressure hydraulic pressure of the high-pressure control system through the second hydraulic valve.

[0037] Optionally, the downhole safety valve high-pressure control branch includes a fourth pressure transmitter, a fourth pressure gauge, and a second shielded valve connected in sequence;

[0038] The fourth pressure transmitter is connected to the output terminal of the high-pressure control main circuit of the downhole safety valve and the output terminal of the low-pressure control branch circuit of the downhole safety valve, respectively.

[0039] The second shielding valve is used to isolate the control system from the downhole safety valve so as to keep the downhole safety valve open when the high-pressure control system is under maintenance.

[0040] Optionally, the low-pressure control system further includes a pressure regulating valve, a pilot pressure gauge, a pressurizing valve, and a pilot check valve connected in series.

[0041] One end of the pressure regulating valve is connected to the input end of the high-pressure control main circuit of the ground safety valve, and the other end is connected to the input end of the pilot pressure gauge;

[0042] One end of the pressurizing valve is connected to the output end of the pilot pressure gauge, and is used to pressurize the low-pressure hydraulic fluid in the fusible plug control branch.

[0043] The input end of the pilot check valve is connected to the other end of the pressurizing valve, and the output end is connected to the low-pressure control branch of the downhole safety valve and the fusible plug control branch, respectively, to prevent the backflow of liquid in the fusible plug control branch;

[0044] The pressure regulating valve and the pilot pressure gauge also include a pilot accumulator, a first unloading valve and a first isolation valve connected in sequence.

[0045] The first unloading valve is connected to the pipeline between the output end of the pilot accumulator and the input end of the first isolation valve, and is used to release the hydraulic pressure of the pilot accumulator.

[0046] The output of the first isolation valve is connected to the low-pressure control system to isolate the pilot accumulator from the control system.

[0047] Optionally, the low-pressure control branch of the ground safety valve includes a first pilot directional valve, a manual main switch valve, a first bypass valve, a first solenoid valve, a throttle valve, a second pilot directional valve, and a delay valve.

[0048] The first pilot directional valve is connected to the pilot pressure gauge, the output end of the pilot check valve, and one end of the throttle valve, respectively, to maintain the hydraulic pressure of the low-pressure control system.

[0049] The other end of the throttle valve is connected to the fusible plug control branch and the second pilot directional valve, respectively, to supplement the low-pressure control system with hydraulic pressure.

[0050] The first port of the manual master switch valve is connected to the pilot pressure gauge and the pipeline of the pilot pressure gauge, the second port is connected to the first port of the first bypass valve, and the third port is connected to the low-pressure control branch of the surface safety valve and the high-pressure control main line of the downhole safety valve, respectively.

[0051] The third port of the first bypass valve is connected to the input end of the first solenoid valve, and the second port is connected to the pipeline between the output end of the first solenoid valve and the second pilot directional valve.

[0052] The input end of the delay valve is connected to the second pilot directional valve, and the output end is connected to the high-pressure control main circuit of the downhole safety valve, which is used to extend the time of the liquid circuit in the control system.

[0053] Optionally, the low-pressure control branch of the ground safety valve includes a third pilot directional valve, a second bypass valve, and a second solenoid valve;

[0054] The first port of the third pilot directional valve is connected to the low-pressure control branch of the downhole safety valve, the second port is connected to the first port of the second bypass valve, and the third port is connected to the high-pressure control main line of the surface safety valve.

[0055] The third port of the second bypass valve is connected to the input end of the second solenoid valve, and the second port is connected to the pipeline between the second solenoid valve and the high-pressure control main line of the ground safety valve.

[0056] Optionally, the fusible plug control branch includes a pressure switch, a fusible plug pressure gauge, and a fusible plug shielding valve connected in sequence;

[0057] One end of the pressure switch is connected to the low-pressure control branch of the downhole safety valve, and the other end is connected to one end of the fusible plug shielded valve through the fusible plug pressure gauge.

[0058] The other end of the fusible plug shielding valve is connected to the fusible plug.

[0059] Optionally, the control system further includes a pilot relief valve, a first relief valve, a second relief valve, a third relief valve, and a fourth relief valve; wherein the pilot relief valve, the first relief valve, the second relief valve, the third relief valve, and the fourth relief valve are all used to release the liquid hydraulic pressure when the liquid hydraulic pressure exceeds a preset value, so as to protect the control system.

[0060] One end of the pilot relief valve is connected to the pipeline between the first isolation valve and the pilot pressure gauge; one end of the first relief valve is connected to the first check valve, the second check valve, the pressure regulating valve and the second isolation valve respectively; one end of the second relief valve is connected to the third check valve and the third shielded valve respectively; one end of the third relief valve is connected to the first hydraulic valve and the second pressure transmitter respectively; one end of the fourth relief valve is connected to the second hydraulic valve and the fourth pressure transmitter respectively.

[0061] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0062] By designing the wellhead safety control system proposed in this application embodiment, the high pressure requirements of future actual production can be met. By controlling the high pressure control system through the low pressure control system, the hydraulic stability in the control system can be maintained. This solves the problem that existing conventional wellhead control panels cannot achieve fully electro-hydraulic automatic control when the pressure reaches high pressure, and realizes fully electro-hydraulic automatic control of the wellhead control panel of ultra-high pressure oil and gas wells. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0064] Figure 1 This is a schematic diagram of the structure of a wellhead safety control system disclosed in an embodiment of this application;

[0065] Figure 2 This is a schematic diagram of another wellhead safety control system disclosed in an embodiment of this application.

[0066] Reference numerals: 1. Oil tank; 2. First filter; 3. Second filter; 4. First ball valve; 5. Second ball valve; 6. First manual pump; 7. First electric pump; 8. Second electric pump; 9. Second manual pump; 10. First check valve; 11. Second check valve; 12. Third check valve; 13. Fourth check valve; 14. First relief valve; 15. Second relief valve; 16. Pressure regulating valve; 17. First unloading valve; 18. Pilot valve 19. Accumulator; 20. First isolation valve; 21. Pilot relief valve; 22. Pilot pressure gauge; 23. Pressurization valve; 24. Pilot check valve; 25. First pilot directional valve; 26. Manual master switch valve; 27. First bypass valve; 28. Throttle valve; 29. ​​Second pilot directional valve; 30. Third pilot directional valve; 31. Second bypass valve; 32. Second solenoid valve; 33. Pressure switch; 34. Fusible plug 35. Pressure gauge; 36. Fusible plug shielded valve; 37. Fusible plug; 38. Second unloading valve; 39. Second accumulator; 40. Second isolation valve; 41. First pressure transmitter; 42. First pressure gauge; 43. Fifth check valve; 44. First hydraulic valve; 45. Third relief valve; 46. Second pressure transmitter; 47. Second shielded valve; 48. Quick relief valve; 49. Ground safety valve; 50. Third 51. Unloading valve; 52. Third accumulator; 53. Third shielded valve; 54. Third pressure transmitter; 55. Third pressure gauge; 56. Booster pump; 57. Sixth check valve; 58. Fourth unloading valve; 59. Fourth accumulator; 60. Fourth shielded valve; 61. Delay valve; 62. Second hydraulic valve; 63. Fourth relief valve; 64. Fourth pressure transmitter; 65. Second shielded valve; 66. Downhole safety valve. Detailed Implementation

[0067] To facilitate understanding of this application, a more complete description of the application will be provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of the application. However, the application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of this application thorough and complete. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0068] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0069] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “under” the other element or feature will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0070] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0071] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0072] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0073] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0074] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0075] As drilling depths increase, wellhead pressure rises accordingly, leading to a corresponding increase in the pressure of wellhead safety control systems. Currently, traditional wellhead safety control systems can only reach a maximum pressure of 30,000 PSI, but some wellhead manufacturers are already developing and producing wellhead products with pressures of 25,000 PSI and 30,000 PSI. An ultra-high pressure wellhead safety control system of 40,000 PSI is needed to meet the production requirements of ultra-high pressure wells, and currently, there are no wellhead safety control systems products available to meet this ultra-high pressure requirement.

[0076] Meanwhile, traditional high-pressure wellhead safety control systems have numerous design flaws during operation. When the downhole safety valve control circuit depressurizes and closes the valve, the accumulator pressure is completely released, resulting in a slow shut-in speed. This slow shut-in speed poses a significant safety risk in the event of a wellhead fire. Furthermore, recharging the accumulator before reopening the well slows down the reopening speed and reduces equipment efficiency. Traditional high-pressure wellhead safety control systems use solenoid valves for switching downhole safety valves, which cannot function properly when temporarily reopening the well due to power outages, failing to meet on-site production needs. The fusible plug circuit in traditional high-pressure wellhead safety control systems uses electrical signal feedback and control; unstable electrical signals pose a risk of loss of control. The fusible plug is a safety device installed in the hydraulic circuit, essentially a safety accessory.

[0077] Therefore, this application provides a wellhead safety control system to improve the working efficiency and reliability of the wellhead safety control system, thereby solving the problem that the existing wellhead safety control system has low pressure and cannot meet the control pressure requirements of ultra-high pressure production wells. It also solves the problems of slow well opening and closing speeds in existing high-pressure wellhead safety control systems, the inconvenience of manual operation, and the problem of failure to close the well due to abnormal electrical signals in the fusible plug circuit.

[0078] For a detailed description of the structure and operating principles of the wellhead safety control system, please refer to [link / reference]. Figure 1 , Figure 1 This is a schematic diagram of the structure of a wellhead safety control system disclosed in an embodiment of this application. The control system includes a high-pressure control system and a low-pressure control system.

[0079] The high-pressure control system includes a main high-pressure control circuit for the surface safety valve, a branch high-pressure control circuit for the surface safety valve, a main high-pressure control circuit for the downhole safety valve, and a branch high-pressure control circuit for the downhole safety valve, used to provide high-pressure hydraulic pressure to the control system. The input end of the main high-pressure control circuit for the surface safety valve is connected to the high-pressure control system, and its output end is connected to the input end of the branch high-pressure control circuit for the surface safety valve. The input end of the main high-pressure control circuit for the downhole safety valve is connected to the high-pressure control system, and its output end is connected to the input end of the branch high-pressure control circuit for the downhole safety valve. The output end of the branch high-pressure control circuit for the surface safety valve is connected to the surface safety valve, and the output end of the branch high-pressure control circuit for the downhole safety valve is connected to the downhole safety valve.

[0080] The low-pressure control system includes a fusible plug control branch, a surface safety valve low-pressure control branch, and a downhole safety valve low-pressure control branch, used to control the high-pressure control system to provide low-pressure hydraulic pressure. The input of the fusible plug control branch is connected to the low-pressure control system, and is connected to the surface safety valve high-pressure control main line and the downhole safety valve high-pressure control main line respectively through the surface safety valve low-pressure control branch and the downhole safety valve low-pressure control branch, with its output connected to the fusible plug. The output of the downhole safety valve low-pressure control branch is connected to the input of the surface safety valve low-pressure control branch.

[0081] Specifically, the input terminal of the high-pressure control system also includes an oil tank 1, a filter, a ball valve, a control pump, and a check valve connected in series. The filter includes a first filter 2 and a second filter 3; the ball valve includes a first ball valve 4 and a second ball valve 5; the control pump includes a first manual pump 6, a first electric pump 7, a second electric pump 8, and a second manual pump 9; and the check valve includes a first check valve 10, a second check valve 11, a third check valve 12, and a fourth check valve 13.

[0082] The first filter 2 is one of the output terminals of the oil tank 1, and is connected to the first ball valve 4. The first ball valve 4 is also connected to the output terminals of the second electric pump 8 and the second manual pump 9, which are connected in parallel. The second filter 3 is the other output terminal of the oil tank 1, and is connected to the second ball valve 5. The second ball valve 5 is connected to the output terminals of the first electric pump 7 and the first manual pump 6, which are connected in parallel. The output terminal of the first manual pump 6 is connected to the input terminal of the first check valve 10, and the output terminal of the first check valve 10 is connected to the input terminal of the low-pressure control system and the input terminal of the high-pressure control main circuit of the surface safety valve. The output terminal of the first electric pump 7 is connected to the input terminal of the second check valve 11, and the output terminal of the second check valve 11 is connected to the input terminal of the low-pressure control system and the input terminal of the high-pressure control main circuit of the surface safety valve. The output terminal of the second electric pump 8 is connected to the input terminal of the third check valve 12, and the output terminal of the third check valve 12 is connected to the input terminal of the high-pressure control main circuit of the downhole safety valve. The output end of the second manual pump 9 is connected to the input end of the fourth check valve 13, and the output end of the fourth check valve 13 is connected to the input end of the high-pressure control main circuit of the downhole safety valve.

[0083] The outputs of the first check valve 10 and the second check valve 11 are connected to the input of the high-pressure control main circuit of the ground safety valve and also to the input of the low-pressure control system. The high-pressure control main circuit of the ground safety valve includes a second accumulator 38. The output of the second accumulator 38 is connected to the high-pressure control main circuit of the ground safety valve. The high-pressure control main circuit of the ground safety valve also includes, in sequence, a second unloading valve 37, a second isolation valve 39, a first pressure transmitter 40, a first pressure gauge 41, a fifth check valve 42, and a first hydraulic valve 43, all connected to the second accumulator 38. The second unloading valve 37 is connected to the pipeline between the output of the second accumulator 38 and the input of the second isolation valve 39. The output of the second isolation valve 39 is connected to the high-pressure control main circuit of the ground safety valve to isolate the second accumulator 38 from the control system. The first hydraulic valve 43 is connected to the output of the high-pressure control main circuit of the ground safety valve, the input of the high-pressure control branch of the ground safety valve, and the output of the low-pressure control branch of the ground safety valve. In one embodiment, the first hydraulic valve 43 is a three-way valve.

[0084] The high-pressure control branch of the ground safety valve includes a second pressure transmitter 45, a second pressure gauge 46, a first shielded valve 47, and a quick-release valve 48 connected in sequence. The second pressure transmitter 45 is connected to the output terminal of the high-pressure control main branch of the ground safety valve and the output terminal of the low-pressure control branch of the ground safety valve, respectively. One end of the quick-release valve 48 is connected to the first shielded valve 47, and the other end is connected to the ground safety valve 49.

[0085] The downhole safety valve high-pressure control main circuit includes a third accumulator 51 and a fourth accumulator. The outputs of both the third and fourth accumulators are connected to the downhole safety valve high-pressure control main circuit. The downhole safety valve high-pressure control main circuit also includes a first branch and a second branch. A second electric pump 8 is installed on the first branch, and the output of the third accumulator 51 is connected to the first branch. The outputs of both the first and second branches are connected to the downhole safety valve high-pressure control main circuit. The first branch also includes, in sequence, a third unloading valve 50, a third shielded valve 52, a third pressure transmitter 53, a third pressure gauge 54, a booster pump 55, and a sixth check valve 56, all connected to the third accumulator 51. The third unloading valve 50 is connected to the pipeline between the output of the third accumulator 51 and the input of the third shielded valve 52. The output of the third shielded valve 52 is connected to the first branch. The input of the booster pump 55 is connected to the output of the third shielded valve 52, and its output is connected to one end of the sixth check valve 56. The other end of the sixth check valve 56 is connected to the high-pressure control main circuit of the downhole safety valve.

[0086] The downhole safety valve high-pressure control main circuit also includes a fourth unloading valve 57, a fourth shielded valve 59, and a second hydraulic valve 61, which are sequentially connected to the fourth accumulator 58. The fourth unloading valve 57 is connected to the pipeline between the output end of the fourth accumulator 58 and the input end of the fourth shielded valve 59. The output end of the fourth shielded valve 59 is connected to the surface safety valve high-pressure control main circuit. The second hydraulic valve 61 is connected to the output end of the downhole safety valve high-pressure control main circuit, the input end of the downhole safety valve 66 high-pressure control branch circuit, and the output end of the downhole safety valve 66 low-pressure control branch circuit. In one embodiment, the second hydraulic valve 61 is a three-way valve.

[0087] The high-pressure control branch of the downhole safety valve 66 includes a fourth pressure transmitter 63, a fourth pressure gauge 64, and a second shielded valve 65 connected in sequence. The pipeline measured by the fourth pressure transmitter 63 is located on the high-pressure control branch of the downhole safety valve 66 and is connected to the output terminals of both the high-pressure control main branch and the low-pressure control branch of the downhole safety valve 66. One end of the second shielded valve 65 is connected to the fourth pressure gauge 64, and the other end is connected to the downhole safety valve 66, used to isolate the control system from the downhole safety valve 66.

[0088] The input side of the low-pressure control system includes a pressure regulating valve 16, a pilot pressure gauge 21, a pressurizing valve 22, and a pilot check valve 23 connected in series. One end of the pressure regulating valve 16 is connected to the input of the high-pressure control main circuit of the surface safety valve, and also to the output of the first check valve 10 and the second check valve 11; the other end is connected to the input of the pilot pressure gauge 21. One end of the pressurizing valve 22 is connected to the output of the pilot pressure gauge 21. The input of the pilot check valve 23 is connected to the other end of the pressurizing valve 22, and its output is connected to the low-pressure control branch of the downhole safety valve 66 (including the first pilot directional valve 24 and the second pilot directional valve 29) and the control branch of the fusible plug 36 (including the pressure switch 33). Between the pressure regulating valve 16 and the pilot pressure gauge 21, there is also a pilot accumulator 18, a first unloading valve 17, and a first isolation valve 19 connected in series. The first unloading valve 17 is connected to the pipeline between the output end of the pilot accumulator 18 and the input end of the first isolation valve 19. The output end of the first isolation valve 19 is connected to the low-pressure control system, specifically, the pipeline between the pressure regulating valve 16 and the pilot pressure gauge 21.

[0089] The low-pressure control branch of the surface safety valve includes a first pilot directional valve 24, a manual main switch valve 25, a first bypass valve 26, a first solenoid valve 27, a throttle valve 28, a second pilot directional valve 29, and a delay valve 60. One end of the first pilot directional valve 24 is connected to both the pilot pressure gauge 21 and the manual main switch valve 25, and another end is connected to the throttle valve 28. The other end is connected to the pipeline between the output of the pilot check valve 23 and the pressure switch 33. The other end of the throttle valve 28 is connected to the fusible plug 36 control branch and the second pilot directional valve 29. The first port of the manual main switch valve 25 is connected to the pipeline between the pilot pressure gauge 21 and the pilot pressure gauge 26, the second port is connected to the first port of the first bypass valve 26, and the third port is connected to both the surface safety valve low-pressure control branch and the downhole safety valve high-pressure control main branch. The third port of the first bypass valve 26 is connected to the input of the first solenoid valve 27, and the second port is connected to the pipeline between the output of the first solenoid valve 27 and the second pilot directional valve 29. The input of the delay valve 60 is connected to the second pilot directional valve 29, and the output is connected to the high-pressure control main line of the downhole safety valve.

[0090] The low-pressure control branch of the surface safety valve includes a third pilot directional valve 30, a second bypass valve 31, and a second solenoid valve 32. Specifically, the first port of the third pilot directional valve 30 is connected to the low-pressure control branch of the downhole safety valve 66 (the pipeline between the second pilot directional valve 29 and the delay valve 60), the second port is connected to the first port of the second bypass valve 31, and the third port is connected to the high-pressure control main line of the surface safety valve. The third port of the second bypass valve 31 is connected to the input terminal of the second solenoid valve 32, and the second port is connected to the pipeline between the second solenoid valve 32 and the high-pressure control main line of the surface safety valve. It should be noted that the second port of the second bypass valve 31 is also connected to the pipeline between the third pilot directional valve 30 and the high-pressure control main line and branch of the surface safety valve.

[0091] The fusible plug 36 control branch includes a pressure switch 33, a fusible plug pressure gauge 34, and a fusible plug shielded valve 35 connected in sequence. One end of the pressure switch 33 is connected to the low-pressure control branch of the downhole safety valve 66 (including one end of the pilot directional valve, one end of the throttle valve 28, and one end of the second pilot directional valve 29), and the other end is connected to one end of the fusible plug shielded valve 35 through the fusible plug pressure gauge 34. The other end of the fusible plug shielded valve 35 is connected to the fusible plug 36.

[0092] The control system also includes a pilot relief valve 20, a first relief valve 14, a second relief valve 15, a third relief valve 44, and a fourth relief valve 62. One end of the pilot relief valve 20 is connected to the pipeline between the first isolation valve 19 and the pilot pressure gauge 21. One end of the first relief valve 14 is connected to the first check valve 10, the second check valve 11, the pressure regulating valve 16, and the second isolation valve 39. One end of the second relief valve 15 is connected to the third check valve 12 and the third shielded valve 52. One end of the third relief valve 44 is connected to the first hydraulic valve 43 and the second pressure transmitter 45. One end of the fourth relief valve 62 is connected to the second hydraulic valve 61 and the fourth pressure transmitter 63.

[0093] Based on the connection relationships of the components described above, and considering the working principle of each component in this control system, it can be seen that the oil tank 1 is used to store hydraulic oil. The first filter 2 and the second filter 3 are used to remove impurities from the hydraulic oil and provide clean hydraulic oil to the control system. The first ball valve 4 and the second ball valve 5 are used to shut off the fluid circuit when the control system is under maintenance. The first manual pump 6 and the second manual pump 9 are used to manually provide high-pressure hydraulic pressure to the control system when there is no power. The first electric pump 7 and the second electric pump 8 can provide hydraulic pressure to the control system through the controller. Correspondingly, the first check valve 10, the second check valve 11, the third check valve 12, and the fourth check valve 13 are all used to protect the manual pump or the electric pump. For example, the second check valve 11 can be used to protect the first electric pump 7.

[0094] Pilot relief valve 20, first relief valve 14, second relief valve 15, third relief valve 44, and fourth relief valve 62 are used to protect the control system. When the hydraulic pressure exceeds the set value, it can automatically release pressure. For example, the set value of the first relief valve 14 is 40000 PSI. When the hydraulic pressure of the hydraulic oil flowing through the high-pressure control main circuit of the ground safety valve reaches 40000 PSI, the first relief valve 14 will automatically release pressure to release the hydraulic oil flowing through the high-pressure control main circuit of the ground safety valve, thereby releasing the hydraulic pressure.

[0095] The pressure regulating valve 16 provides a low-pressure hydraulic source for the pilot control circuit. Specifically, the pilot control circuit is a low-pressure control circuit that uses low pressure to control the valves in the high-pressure circuit. Various logic controls can be easily implemented in the low-pressure circuit to control the high-pressure valves. In the control system applied to the embodiments of this application, the low-pressure control system controls the high-pressure control system through the first hydraulic valve 43 and the second hydraulic valve 61 respectively.

[0096] Pilot accumulator 18, second accumulator 38, third accumulator 51, and fourth accumulator 58 are used to store hydraulic oil, i.e., hydraulic pressure, and to maintain the stability of the hydraulic pressure in the control system to reduce pressure fluctuations. First unloading valve 17, second unloading valve 37, third unloading valve 50, and fourth unloading valve 57 are used to release the hydraulic pressure from pilot accumulator 18, second accumulator 38, third accumulator 51, and fourth accumulator 58, respectively. Specifically, during maintenance or replacement of the accumulators, the high-pressure hydraulic pressure in the accumulators can be released through the operation of the unloading valves, allowing the accumulators to be disassembled for maintenance. First isolation valve 19, second isolation valve 39, third shielding valve 52, and fourth shielding valve 59 are used to isolate pilot accumulator 18, second accumulator 38, third accumulator 51, and fourth accumulator 58 from the control system, respectively.

[0097] The pressurizing valve 22 is used to pressurize the fusible plug 36 control branch, i.e., the fusible plug 36 circuit, during the initial operation of the control system. The pilot check valve 23 is used to prevent backflow in the fusible plug 36 circuit. The first pilot directional valve 24 is used to continuously pressurize the fusible plug 36 circuit, thereby maintaining stable hydraulic pressure. The throttle valve 28 is used to replenish pressure in the fusible plug 36 circuit during normal operation of the control system. Simultaneously, since the fusible plug 36 will release pressure when it melts due to a fire, the throttle valve 28 can also be used to limit excessively rapid pressure replenishment.

[0098] Pilot pressure gauge 21, fusible plug pressure gauge 34, first pressure gauge 41, second pressure gauge 46, third pressure gauge 54 and fourth pressure gauge 64 are all used to identify the hydraulic pressure of the corresponding connected pipeline. First pressure transmitter 40, second pressure transmitter 45, third pressure transmitter 53 and fourth pressure transmitter 63 are all used to measure the hydraulic pressure of the corresponding connected pipeline and convert the hydraulic pressure into an electrical signal.

[0099] The booster pump 55 is used to increase the front-end pressure, i.e. the hydraulic pressure of the liquid oil flowing through the third pressure gauge 54, to the rated working pressure of 40000 PSI. The sixth check valve 56 is used to prevent high-pressure backflow in the output circuit of the high-pressure control system.

[0100] The first shielding valve 47 and the second shielding valve 65 can respectively isolate the control system in this embodiment from the field control objects, the surface safety valve 49 and the downhole safety valve 66. During maintenance of the high-pressure control system, the surface safety valve 49 and the downhole safety valve 66 can remain open. Specifically, during maintenance, the first shielding valve 47 and the second shielding valve 65 are closed, thus preventing pressure release at the downstream end (i.e., the surface safety valve 49 and the downhole safety valve 66), ensuring that the surface safety valve 49 and the downhole safety valve 66 remain open. The quick-release valve 48 can be used to quickly close the surface safety valve 49. Specifically, the quick-release valve 48 has a separate, large-diameter release port, which can quickly release pressure.

[0101] Based on the above working principle, when a fire occurs, after the pressure in the fusible plug 36 circuit is released, the first pilot directional valve 24 will automatically close, thereby completely releasing the downstream pressure (and the hydraulic pressure of the throttle valve 28, the second pilot directional valve 29, the third pilot directional valve 30, the second bypass valve 31, and the second solenoid valve 32), and the fusible plug 36 circuit will no longer be pressurized. After the pressure in the fusible plug 36 circuit is released, the second pilot directional valve 29 will also automatically close (it should be noted that when the pressurizing valve 22 is pressurized, the second pilot directional valve 29 will reopen and operate), releasing the control hydraulic pressure of the manual master switch valve 25, the first bypass valve 26, and the first solenoid valve 27. The manual master switch valve 25 will automatically close, further closing the third pilot directional valve 30 and the first hydraulic valve 43, and finally closing the second hydraulic valve 61. The delay valve 60 will cause the liquid circuit closing time to be extended, thereby achieving the delayed closing of the second hydraulic valve 61. It is easy to understand that the second hydraulic valve 61 is a delayed-closing valve, and the other components mentioned above can be understood as closing simultaneously. Moreover, the second hydraulic valve 61 will only close after the pressure is released, and the release pipeline will be restricted by the delay valve 60. The delay valve 60 can adjust the hydraulic flow rate, thereby controlling the closing time of the second hydraulic valve 61.

[0102] When the manual master valve 25 is closed, the third pilot directional valve 30 and the first hydraulic valve 43 will also automatically close. It is easy to understand that when the manual master valve 25 is closed, the pressure in the downstream circuit is released, so the downstream valves also close.

[0103] Finally, both the surface safety valve 49 and the downhole safety valve 66 are closed. It should be noted that when the second hydraulic valve 61 is closed, the pressure in the entire circuit downstream of the second hydraulic valve 61 is released, and the downhole safety valve will close when there is no pressure.

[0104] In one embodiment, the conventional method is that after the fusible plug 36 circuit is depressurized, the pressure switch 33 feeds back an electrical signal to the control system, and then controls the first solenoid valve 27 through the electrical signal to achieve the system shutdown. When the electrical signal fails, effective shutdown cannot be guaranteed, which poses a huge safety risk.

[0105] Therefore, the first bypass valve 26 can bypass the first solenoid valve 27 by switching the circuit, and the manual main switch valve 25 can still be opened normally when there is no power on site. The second bypass valve 31 can bypass the second solenoid valve 32 by switching the circuit, and the manual main switch valve 25 can still be opened normally when there is no power on site.

[0106] This embodiment uses a second hydraulic valve 61 to control the pressure increase and decrease of the output circuit. Specifically, when the second hydraulic valve 61 opens, it transmits the pressure before the valve to the subsequent circuit. When the second hydraulic valve 61 closes, it releases the pressure in the subsequent circuit. The opening and closing of the second hydraulic valve 61 can be referred to the previous shutdown process. That is, when the second hydraulic valve 61 closes, it only releases the pressure at the downstream end, while the pressure in the upstream circuit and the third accumulator 51 remains unchanged. This results in a fast shut-in speed and quick reopening, with fast response and high safety. Traditional methods use two-way pressure relief valves, which release all the pressure in the entire circuit and the third accumulator 51 when the circuit is closed, affecting the shut-in speed. Furthermore, when reopening, the accumulator needs to be recharged, affecting the reopening speed, resulting in low efficiency and safety hazards. It should be noted that the first hydraulic valve 43 and the second hydraulic valve 61 can be three-way valves.

[0107] In another embodiment, please refer to Figure 2 , Figure 2 This is a schematic diagram of another wellhead safety control system disclosed in an embodiment of this application.

[0108] It is not hard to understand that Figure 2 and Figure 1 In contrast, the first unloading valve 17, the second unloading valve 37, and the third unloading valve 50 are no longer required. In another specific embodiment, the first isolation valve 19, the second isolation valve 39, and the third shielding valve 52 may also be omitted. The absence of the aforementioned first unloading valve 17, second unloading valve 37, third unloading valve 50, first isolation valve 19, second isolation valve 39, and third shielding valve 52 will not affect the basic control functions of the various devices in the wellhead safety control system.

[0109] Correspondingly, the reduction of some pressure gauges and transmitters in the system may not affect the basic functions of each device in the wellhead safety control system. For example, a first pressure gauge 41 may be provided in the control system proposed in this application embodiment, or the first pressure transmitter 40 may not be provided. Specifically, there are no restrictions on the specific contents of the reduced pressure gauges or pressure transmitters.

[0110] Correspondingly, the first bypass valve 26, the second bypass valve 31, and the second hydraulic valve 61 are all three-way valves. The three-way valve can also achieve the same function by combining two two-way valves.

[0111] Correspondingly, all the directional valves described in the embodiments of this application can be opened manually or closed automatically or remotely.

[0112] It should also be noted that, Figure 2 In the middle, one end of the second hydraulic valve 61 is also provided with an oil return tank, which can also be used for pressure relief.

[0113] In summary, the wellhead safety control system proposed in this application, with its 40,000 PSI high-pressure wellhead safety control system, can meet the high-pressure requirements of future actual production. Simultaneously, by designing a three-way pressure relief valve, pressure relief is achieved only at the rear end of the circuit, not at the front end, improving both well opening and shut-in speeds and preventing accidents caused by slow shut-in in emergencies, while also improving equipment efficiency. Furthermore, the manual bypass function solves the problem of inconvenient manual operation of the high-pressure wellhead safety control system, allowing manual operation of the equipment even in the absence of power. Moreover, the interlocking control circuit design solves the problem of failure to shut down the well due to abnormal electrical signals in the fusible plug circuit, improving equipment reliability and eliminating the risk of automatic shut-in failure in emergencies.

[0114] If the plan involves sensitive information (such as user information or corporate information), it should state that the collection, use, and processing of sensitive information must comply with the laws, regulations, and standards of the relevant countries and regions, and must be carried out with the permission or consent of the relevant parties (such as users or companies).

[0115] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A wellhead safety control system, characterized in that, The control system includes a high-voltage control system and a low-voltage control system; The high-pressure control system includes a surface safety valve high-pressure control main circuit, a surface safety valve high-pressure control branch circuit, a downhole safety valve high-pressure control main circuit, and a downhole safety valve high-pressure control branch circuit, used to provide high-pressure hydraulic pressure to the control system. The input end of the surface safety valve high-pressure control main circuit is connected to the high-pressure control system, and its output end is connected to the input end of the surface safety valve high-pressure control branch circuit. The input end of the downhole safety valve high-pressure control main circuit is connected to the high-pressure control system, and its output end is connected to the input end of the downhole safety valve high-pressure control branch circuit. The output end of the surface safety valve high-pressure control branch circuit is connected to the surface safety valve, and the output end of the downhole safety valve high-pressure control branch circuit is connected to the downhole safety valve. The low-pressure control system includes a fusible plug control branch, a surface safety valve low-pressure control branch, and a downhole safety valve low-pressure control branch, used to control the high-pressure control system to provide low-pressure hydraulic pressure. The input end of the fusible plug control branch is connected to the low-pressure control system, and is connected to the surface safety valve high-pressure control main circuit and the downhole safety valve high-pressure control main circuit respectively through the surface safety valve low-pressure control branch and the downhole safety valve low-pressure control branch, respectively, and its output end is connected to the fusible plug. The output end of the downhole safety valve low-pressure control branch is connected to the input end of the surface safety valve low-pressure control branch. The high-pressure control main circuit of the ground safety valve also includes a first hydraulic valve, which is connected to the output end of the high-pressure control main circuit of the ground safety valve, the input end of the high-pressure control branch circuit of the ground safety valve, and the output end of the low-pressure control branch circuit of the ground safety valve, so that the low-pressure control system controls the high-pressure hydraulic pressure of the high-pressure control system through the first hydraulic valve. The downhole safety valve high-pressure control main circuit also includes a second hydraulic valve, which is connected to the output end of the downhole safety valve high-pressure control main circuit, the input end of the downhole safety valve high-pressure control branch circuit, and the output end of the downhole safety valve low-pressure control branch circuit, so that the low-pressure control system controls the high-pressure hydraulic pressure of the high-pressure control system through the second hydraulic valve. The low-pressure control branch of the surface safety valve includes a second pilot directional valve and a time-delay valve. The input end of the time-delay valve is connected to the second pilot directional valve, and the output end is connected to the high-pressure control main branch of the downhole safety valve, which is used to extend the time of the liquid circuit in the control system.

2. The wellhead safety control system according to claim 1, characterized in that, The high-pressure control system also includes an oil tank, a filter, a ball valve, a control pump, and a check valve connected in series. The filter includes a first filter and a second filter installed in parallel; the ball valve includes a first ball valve and a second ball valve installed in parallel; the control pump includes a first manual pump, a first electric pump, a second electric pump, and a second manual pump; the check valve includes a first check valve, a second check valve, a third check valve, and a fourth check valve. The first ball valve is connected to the output end of the second electric pump and the output end of the second manual pump, which are connected in parallel. The second ball valve is connected to the output end of the first electric pump and the output end of the first manual pump, which are connected in parallel. It is used to shut down the circuit of the control system when the control system is under maintenance. The output end of the first manual pump is connected to the input end of the first check valve, and the output end of the first check valve is connected to the input end of the low-pressure control system and the input end of the high-pressure control main circuit of the ground safety valve, respectively. The output end of the first electric pump is connected to the input end of the second check valve, and the output end of the second check valve is connected to the input end of the low-pressure control system and the input end of the high-pressure control main circuit of the ground safety valve, respectively. The output end of the second electric pump is connected to the input end of the third check valve, and the output end of the third check valve is connected to the input end of the high-pressure control main circuit of the downhole safety valve. The output end of the second manual pump is connected to the input end of the fourth one-way valve, and the output end of the fourth one-way valve is connected to the input end of the high-pressure control main circuit of the downhole safety valve.

3. The wellhead safety control system according to claim 2, characterized in that, The high-pressure control main circuit of the ground safety valve includes a second accumulator. The output end of the second accumulator is connected to the high-pressure control main circuit of the ground safety valve to store hydraulic pressure in order to maintain the pressure of the control system.

4. The wellhead safety control system according to claim 3, characterized in that, The high-pressure control main circuit of the ground safety valve also includes a second unloading valve, a second isolation valve, a first pressure transmitter, a first pressure gauge, and a fifth check valve, which are connected in sequence to the second accumulator. The second unloading valve is connected to the pipeline between the output end of the second accumulator and the input end of the second isolation valve, and is used to release the high pressure hydraulic pressure of the second accumulator; The output of the second isolation valve is connected to the high-pressure control main circuit of the ground safety valve, which is used to isolate the second accumulator from the control system.

5. The wellhead safety control system according to claim 4, characterized in that, The high-pressure control branch of the ground safety valve includes a second pressure transmitter, a second pressure gauge, a first shielded valve, and a quick relief valve connected in sequence. The second pressure transmitter is connected to the output terminal of the high-pressure control main circuit of the ground safety valve and the output terminal of the low-pressure control branch circuit of the ground safety valve, respectively. The first shielding valve is used to isolate the control system from the ground safety valve so as to keep the ground safety valve open when the high-voltage control system is under maintenance; One end of the quick-release valve is connected to the first shielded valve, and the other end is connected to the ground safety valve; the quick-release valve also includes a vent for releasing high-pressure hydraulic pressure.

6. The wellhead safety control system according to claim 5, characterized in that, The downhole safety valve high-pressure control main circuit includes a third accumulator and a fourth accumulator; The output terminals of the third accumulator and the fourth accumulator are connected to the high-pressure control main circuit of the downhole safety valve to store hydraulic pressure in order to maintain the pressure of the control system. The downhole safety valve high-pressure control main circuit also includes a first branch circuit and a second branch circuit; wherein, the first branch circuit is equipped with an electric pump, and the output end of the third accumulator is connected to the first branch circuit; the output ends of the first branch circuit and the second branch circuit are both connected to the downhole safety valve high-pressure control main circuit.

7. The wellhead safety control system according to claim 6, characterized in that, The first branch also includes a third unloading valve, a third shielding valve, a third pressure transmitter, a third pressure gauge, a booster pump, and a sixth check valve, which are connected in sequence to the third accumulator. The third unloading valve is connected to the pipeline between the output end of the third accumulator and the input end of the third shielded valve, and is used to release the high-pressure hydraulic pressure of the third accumulator. The output end of the third shielding valve is connected to the first branch, which is used to isolate the third accumulator from the control system; The input end of the booster pump is connected to the output end of the third shielded valve, and the output end is connected to one end of the sixth check valve, which is used to boost the high pressure hydraulic pressure of the first branch to the target working pressure. The other end of the sixth check valve is connected to the high-pressure control main circuit of the downhole safety valve, and is used to prevent the backflow of liquid in the high-pressure control main circuit of the downhole safety valve.

8. The wellhead safety control system according to claim 7, characterized in that, The downhole safety valve high-pressure control main circuit also includes a fourth unloading valve and a fourth shielding valve connected in sequence to the fourth accumulator; The fourth unloading valve is connected to the pipeline between the output end of the fourth accumulator and the input end of the fourth shielded valve, and is used to release the high pressure hydraulic pressure of the fourth accumulator. The output end of the fourth shielding valve is connected to the high-pressure control main circuit of the ground safety valve, which is used to isolate the fourth accumulator from the control system.

9. The wellhead safety control system according to claim 8, characterized in that, The downhole safety valve high-pressure control branch includes a fourth pressure transmitter, a fourth pressure gauge, and a second shielded valve connected in sequence. The fourth pressure transmitter is connected to the output terminal of the high-pressure control main circuit of the downhole safety valve and the output terminal of the low-pressure control branch circuit of the downhole safety valve, respectively. The second shielding valve is used to isolate the control system from the downhole safety valve so as to keep the downhole safety valve open when the high-pressure control system is under maintenance.

10. The wellhead safety control system according to claim 9, characterized in that, The low-pressure control system also includes a pressure regulating valve, a pilot pressure gauge, a pressurizing valve, and a pilot check valve connected in series. One end of the pressure regulating valve is connected to the input end of the high-pressure control main circuit of the ground safety valve, and the other end is connected to the input end of the pilot pressure gauge; One end of the pressurizing valve is connected to the output end of the pilot pressure gauge, and is used to pressurize the low-pressure hydraulic fluid in the fusible plug control branch. The input end of the pilot check valve is connected to the other end of the pressurizing valve, and the output end is connected to the low-pressure control branch of the downhole safety valve and the fusible plug control branch, respectively, to prevent the backflow of liquid in the fusible plug control branch; The pressure regulating valve and the pilot pressure gauge also include a pilot accumulator, a first unloading valve and a first isolation valve connected in sequence. The first unloading valve is connected to the pipeline between the output end of the pilot accumulator and the input end of the first isolation valve, and is used to release the hydraulic pressure of the pilot accumulator. The output of the first isolation valve is connected to the low-pressure control system to isolate the pilot accumulator from the control system.

11. The wellhead safety control system according to claim 10, characterized in that, The low-pressure control branch of the ground safety valve includes a first pilot directional valve, a manual main switch valve, a first bypass valve, a first solenoid valve, and a throttle valve. The first pilot directional valve is connected to the pilot pressure gauge, the output end of the pilot check valve, and one end of the throttle valve, respectively, to maintain the hydraulic pressure of the low-pressure control system. The other end of the throttle valve is connected to the fusible plug control branch and the second pilot directional valve, respectively, to supplement the low-pressure control system with hydraulic pressure. The first port of the manual master switch valve is connected to the pilot pressure gauge and the pipeline of the pilot pressure gauge, the second port is connected to the first port of the first bypass valve, and the third port is connected to the low-pressure control branch of the surface safety valve and the high-pressure control main line of the downhole safety valve, respectively. The third port of the first bypass valve is connected to the input end of the first solenoid valve, and the second port is connected to the pipeline between the output end of the first solenoid valve and the second pilot directional valve.

12. The wellhead safety control system according to claim 11, characterized in that, The low-pressure control branch of the ground safety valve includes a third pilot directional valve, a second bypass valve, and a second solenoid valve. The first port of the third pilot directional valve is connected to the low-pressure control branch of the downhole safety valve, the second port is connected to the first port of the second bypass valve, and the third port is connected to the high-pressure control main line of the surface safety valve. The third port of the second bypass valve is connected to the input end of the second solenoid valve, and the second port is connected to the pipeline between the second solenoid valve and the high-pressure control main line of the ground safety valve.

13. The wellhead safety control system according to claim 12, characterized in that, The fusible plug control branch includes a pressure switch, a fusible plug pressure gauge, and a fusible plug shielding valve connected in sequence. One end of the pressure switch is connected to the low-pressure control branch of the downhole safety valve, and the other end is connected to one end of the fusible plug shielded valve through the fusible plug pressure gauge. The other end of the fusible plug shielding valve is connected to the fusible plug.

14. The wellhead safety control system according to claim 13, characterized in that, The control system further includes a pilot relief valve, a first relief valve, a second relief valve, a third relief valve, and a fourth relief valve; wherein, the pilot relief valve, the first relief valve, the second relief valve, the third relief valve, and the fourth relief valve are all used to release the liquid hydraulic pressure when the liquid hydraulic pressure exceeds a preset value, so as to protect the control system. One end of the pilot relief valve is connected to the pipeline between the first isolation valve and the pilot pressure gauge; one end of the first relief valve is connected to the first check valve, the second check valve, the pressure regulating valve and the second isolation valve respectively; one end of the second relief valve is connected to the third check valve and the third shielded valve respectively; one end of the third relief valve is connected to the first hydraulic valve and the second pressure transmitter respectively; one end of the fourth relief valve is connected to the second hydraulic valve and the fourth pressure transmitter respectively.

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