Shear control method for high-low pressure dual-circuit surface blowout preventer

Abstract

The present invention discloses a shear control method for a high-low pressure dual-circuit surface blowout preventer, comprising a shear closing control process and a shear opening control process; after receiving a "one-button shear closing" signal, a PLC simultaneously controls the low-pressure valve to open and the pressure relief valve to close, and controls the shear valve to a closed position after a delay T1, and the hydraulic oil in the low-pressure accumulator pushes the shear gate to start closing, and determines whether relevant requirements for executing the action are met. If so, the relevant action is executed; after receiving a "one-button shear opening" signal, the PLC sequentially controls the closing of the high-pressure valve, the opening of the pressure relief valve, and the opening of the low-pressure valve to release the high-pressure hydraulic oil in the shear pipeline, and then opens the shear valve to control the shear gate to open; when the method closes the shear blowout preventer, low-pressure oil is used for no-load operation, and the design of the high-pressure oil shear string realizes automatic switching of high- and low-pressure hydraulic oil in the system.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling, and in particular to a shear control method for a high-low pressure dual-circuit surface blowout preventer. Background Art

[0002] BOPs are safety devices that control well pressure. The shear ram installed in them must be used to cut off the operating pipe in an emergency to ensure safe well sealing.

[0003] However, conventional drilling blowout preventers and their associated hydraulic control devices can only cut conventional drill pipes. If the pipe string is exactly at the position of a drill collar of 6.5 inches or less or at the position of a drill pipe coupling of 5.7 / 8 inches or less, the conventional shear ram blowout preventer cannot cut the pipe string in the well.

[0004] The research and development of the "Large Thrust Shear Ram BOP and High-Low Pressure Dual-Circuit Surface BOP Control Device" project enables the shearing of drill collars 6 1 / 2" and below or drill pipe couplings 5 ​​7 / 8" and below, thereby ensuring safe operations during drilling operations.

[0005] The main feature of the high-low pressure dual-circuit surface BOP control system is that it uses low-pressure hydraulic oil when the BOP is operating without load, switching to high-pressure hydraulic oil when shearing drill collars. Because this operation is complex, manual operation can lead to panic and errors in emergencies. Designing an electrical control system that implements "one-click shearing" can avoid these situations. Summary of the Invention

[0006] The purpose of the present invention is to provide a shear control method for a high-low pressure dual-circuit surface blowout preventer.

[0007] To this end, the technical solution of the present invention is as follows:

[0008] The present invention provides a shear control method for a high-low pressure dual-circuit surface blowout preventer, including a shear closing control process and a shear opening control process;

[0009] Shear shutoff control process: After receiving the "one-button shear shutoff" signal, the PLC simultaneously controls the low-pressure valve to open and the pressure relief valve to close. After a delay of T1, the shear valve is controlled to the closed position. The hydraulic oil in the low-pressure accumulator pushes the shear gate to start closing. After a delay of T2, it is determined whether the first requirement for executing the first action is met. If so, the first action is executed. If not, the determination is continued until the second requirement for executing the first action is met, and then the first action is executed. The first action is to immediately open the high-pressure valve to allow the high-pressure accumulator hydraulic oil to flow into the shear shutoff pipeline.

[0010] Shear opening control process: When the "one-button shear closing" function has been used during the drilling process and the "one-button shear opening" function is required after the problem is resolved, after receiving the "one-button shear opening" signal, the PLC controls the high-pressure valve to close, the pressure relief valve to open, the low-pressure valve to open, and the shear valve to the open position in sequence to release the high-pressure hydraulic oil in the shear pipeline and control the shear gate to open. The time interval for the above valve actions is T1.

[0011] Furthermore, the first requirement is that the pressure difference between the low-pressure accumulator and the shear valve is less than 0.5 MPa 15 seconds after the PLC detects the shear valve closed position signal; the second requirement is that the timing is full 20 seconds after the PLC detects the shear valve closed position signal.

[0012] Furthermore, it also includes an initialization control process, specifically:

[0013] After receiving the initialization instruction, the PLC switches each valve to the set position. Each valve realizes the switching of the switch position by controlling the solenoid valve. The electromagnet of each solenoid valve is energized for 5 seconds and then de-energized. After the valve is in place, the corresponding position sensor will feed back the valve position signal to the PLC. At the same time, the PLC transmits the valve position signal to the touch screen for display. If the valve position is correct, it will be green, otherwise it will be red and the PLC controls the sound and light alarm to alarm. Among them, during the initialization process, the low-pressure valve is opened, the high-pressure valve is closed, the shear valve is opened, and the pressure relief valve is closed.

[0014] Furthermore, it also includes an overpressure relief control process, specifically:

[0015] After receiving the differential pressure relief command, the PLC controls the pressure relief valve to open, and after a delay of T1, controls the high-pressure valve to open, unloading the high-pressure oil, and unloading the hydraulic oil in the high-pressure accumulator back to the tank to protect the hydraulic system.

[0016] Furthermore, it also includes the emergency stop control process, specifically:

[0017] Upon receiving the emergency stop command, the PLC controls the low-pressure valve to close and the high-pressure valve to close at the same time, the blowout preventer open and close pipelines stop supplying oil, the blowout preventer immediately stops, and the emergency stop operation control procedure is completed.

[0018] Furthermore, when the PLC operates each valve in sequence according to the instructions, it delays the power-on time of each valve to ensure that each valve switch is in place. After the delay time ends, the solenoid valves are powered off in turn. At the same time, the PLC collects the position switch signals of each valve and displays them on the touch screen. If the valve position is correct, the corresponding valve indicator light is "green", otherwise it is red. If there is an error in the valve position, the corresponding indicator light turns red and the system sound and light alarm is started at the same time.

[0019] Furthermore, the value of T1 is 3 seconds, and the value of T2 is 15 seconds.

[0020] Furthermore, the low-pressure valve and the high-pressure valve are both 70MPa pneumatic ball valves with position feedback signals.

[0021] Furthermore, the shear valve is a hydraulic rotary valve with a position feedback signal, and the solenoid valve is an explosion-proof solenoid valve.

[0022] Compared with existing technologies, this high-low pressure dual-circuit surface blowout preventer shear control method has the following advantages:

[0023] When the shear blowout preventer is closed, low-pressure oil is used for no-load operation. The design of high-pressure oil shearing the pipe string enables the system to automatically switch between high and low pressure hydraulic oil.

[0024] The pressure feedback signal from the pressure sensor is used as the first execution condition for executing high-pressure oil shear. At the same time, a time relay is introduced as another supplementary execution condition for executing high-pressure oil shear to avoid the PLC being unable to execute the action of controlling the high-pressure valve to switch to the open position due to abnormalities in the pressure sensor transmission signal.

[0025] The “Emergency Stop” operation is introduced, which can realize the emergency stop of the shearing action in case of failure or misoperation;

[0026] Introducing overpressure relief control. When the safety relief valve of the hydraulic system fails to work properly and causes the pressure to continue to rise and reach the set value, the overpressure relief control will be activated. The system will automatically open the pressure relief ball valve to release the high-pressure oil, thereby protecting the hydraulic system.

[0027] The introduction of abnormal alarm function can realize the monitoring of data abnormalities of hydraulic system on the one hand, and monitor whether each valve is in place during the linkage operation on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a structural block diagram of the control system adopted by the method adopted by the present invention.

[0029] Figure 2 Flowchart of the initialization control process.

[0030] Figure 3 Flowchart of the shear control process.

[0031] Figure 4 Cut out the flow chart of the control process.

[0032] Figure 5 This is a flow chart of the emergency stop control process.

[0033] Figure 6 Flowchart of the pressure relief control process. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention in any way.

[0035] Unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used in one or more embodiments of this application refers to and is described in many specific details below to facilitate a full understanding of this application. However, this application can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotations of this application. Therefore, this application is not limited to the specific implementations disclosed below.

[0036] The terms used in one or more embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit one or more embodiments of the present application. The singular forms "a", "an", "the" and "the" used in one or more embodiments of the present application and the appended claims are also intended to include plural forms, including any or all possible combinations of one or more associated listed items.

[0037] It should be understood that although the terms first, second, etc. may be used to describe various information in one or more embodiments of the present application, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of one or more embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0038] The shear control method for a high-low pressure dual-circuit surface blowout preventer provided by the present invention includes an initialization control process, a shear closing control process, a shear opening control process, an overpressure relief control process, and an emergency stop control process.

[0039] The control system used in the high and low pressure dual circuit surface blowout preventer shear control method provided by the present invention is as follows: Figure 1 As shown, the control system includes a local control box, a remote driller's control box, a data acquisition module, an execution module, and two touch screens; the local control box is provided with a main control module, which includes a PLC, an analog I / O module, and a digital I / O module; the analog I / O module is connected to the data acquisition module, and the digital I / O module is connected to the execution module; the remote driller's control box is provided with a remote expansion module I / O, which communicates with the main control module using the DP bus;

[0040] The data acquisition module includes a first pressure sensor and a second pressure sensor. The first pressure sensor is used to collect the pressure value of the low-pressure accumulator, and the second pressure sensor is used to collect the shear pressure value. The execution module includes a low-pressure valve, a high-pressure valve, a shear valve, a pressure relief valve and several solenoid valves. The low-pressure valve is used to control the opening and closing of the low-pressure accumulator group, and the high-pressure valve is used to control the opening and closing of the high-pressure accumulator group.

[0041] Combine Figures 1-6 The shear control method of the high-low pressure dual-circuit surface blowout preventer provided by the present invention is described in detail.

[0042] Initialization control process:

[0043] After the electrical control system is turned on, press the initialization button. After receiving the initialization command, the PLC switches each valve to the set position, among which the low-pressure valve opens, the high-pressure valve closes, the shear valve opens, and the pressure relief (pneumatic ball) valve closes.

[0044] After receiving the initialization command, the PLC controls the electromagnet of the explosion-proof solenoid valve to attract. After the explosion-proof solenoid valve electromagnet attracts, the solenoid valve changes direction, thereby controlling the reversal of the corresponding pneumatic valve. In order to ensure that the valve is in place, the PLC adds a delay program. Each solenoid valve electromagnet is energized for 5 seconds and then de-energized. The 5-second delay can ensure that the pneumatic valve is in place. After the pneumatic valve is in place, the corresponding position sensor will feedback the valve position signal to the PLC, and the PLC will transmit the valve position signal to the touch screen for display. After executing the "initialization" program, the initialization program display area shows the position of each valve. If the valve position is correct, it will be green, otherwise it will be red and the PLC will control the sound and light alarm to alarm. After pressing the alarm mute button, the alarm is canceled.

[0045] Shear off control process:

[0046] When an abnormality occurs during the drilling process and shearing is required, the "One-key shearing off" function can be used to achieve one-key shearing. After pressing the "One-key shearing off" button and the PLC receives the "One-key shearing off" program:

[0047] The low-pressure valve solenoid valve opening electromagnet is turned on and delayed for 5 seconds. The solenoid valve opening electromagnet is energized and reversed, controlling the low-pressure valve to reverse to the open position. The low-pressure valve open position signal is fed back to the PLC, and the PLC transmits the low-pressure valve position signal to the touch screen for displaying the valve position.

[0048] When the low-pressure valve solenoid valve is turned on, the pressure relief valve solenoid valve closing electromagnet is turned on and delayed for 5 seconds. The solenoid valve closing electromagnet is energized and reversed to control the pressure relief valve to reverse to the closed position. The pressure relief valve closing position signal is fed back to the PLC, and the PLC transmits the low-pressure valve position signal to the touch screen to display the valve position.

[0049] After the low-pressure valve solenoid is connected and a 3-second timer begins, the shear valve solenoid is connected and a 5-second delay is applied. The solenoid valve closing electromagnet is energized and reversed, controlling the shear valve cylinder to drive the shear valve to the closed position. The shear valve closed position signal is fed back to the PLC, which transmits the shear valve position signal to the touch screen to display the valve position. The electrical control system then controls the low-pressure accumulator hydraulic oil to drive the blowout preventer to close. The PLC detects the shear valve position signal and begins timing. After 20 seconds, the PLC automatically connects the high-pressure valve opening electromagnet and a 5-second delay, causing the high-pressure valve to switch to the open position. At this time, the high-pressure accumulator hydraulic oil is injected into the shear valve closing line, achieving high-pressure shearing of the tubing string. The procedure for automatically connecting the high-pressure valve with a 20-second delay is a backup procedure.

[0050] After the PLC detects the shear valve is in the open position, it begins timing for 15 seconds and then compares the low-pressure accumulator and shear valve pressure values. When the difference between the two pressures is less than 0.5 MPa, it indicates that the blowout preventer gate is in contact with the tubing. The PLC then energizes the high-pressure valve solenoid valve opening electromagnet and delays for 5 seconds. The solenoid valve opening electromagnet is energized and switches to the open position, controlling the high-pressure valve. At this time, hydraulic oil from the high-pressure accumulator is injected into the shear valve pipeline, achieving high-pressure shearing of the tubing. If the PLC is unable to control the high-pressure valve to open due to an abnormal pressure sensor signal, the PLC will execute a backup program that automatically connects the high-pressure valve after a 20-second delay.

[0051] The main purpose of the "one-button shear shutoff" control program is to use the low-pressure accumulator hydraulic oil to start closing the shear gate. Since the shear gate is "idle", the shear shutoff pipeline pressure will be lower than the low-pressure accumulator pressure. When the shear gate contacts the tubing, the shear shutoff pipeline pressure will increase to the same level as the low-pressure accumulator pressure. At this time, the PLC detects the "shear shutoff pressure" and "low-pressure accumulator pressure" through the pressure sensor. When the two pressures are consistent, the high-pressure valve is immediately opened to inject the high-pressure accumulator hydraulic oil into the shear shutoff pipeline, and the high-pressure hydraulic oil is used to achieve shearing.

[0052] To prevent the shear gate from running empty, the pressure signals of the "shear valve pressure sensor" and the "low-pressure accumulator pressure sensor" are consistent due to special reasons, causing the high-pressure valve to open early. Therefore, the PLC starts timing 15 seconds after detecting that the shear valve is in the closed position, and then starts comparing the low-pressure accumulator and shear valve pressure values.

[0053] When the BOP ram is closed (in a "dry run"), low-pressure accumulator hydraulic oil is used. Once the BOP ram contacts the tubing, high-pressure accumulator hydraulic oil is immediately released to achieve high-pressure shearing. When the low-pressure accumulator pressure matches the BOP line (shear) pressure, sufficient contact between the BOP ram and tubing is confirmed.

[0054] In order to prevent the failure of the "one-button shear off" program due to an abnormality in the pressure sensor, a "20-second delay" backup program was added to the PLC control program.

[0055] The delay times in the above procedures are all reasonable data obtained during the test process: the solenoid valve corresponding to each pneumatic valve needs to be energized for 5 seconds to switch the valve into place; the low-pressure accumulator controls the BOP gate for an idle cycle time of between 17 and 19 seconds, so the delay time of the "delay" backup program is set to 20 seconds; to prevent the PLC from checking the pressure differential in advance, which would cause the high-pressure accumulator hydraulic oil to be prematurely supplied before the BOP contacts the tubing, a delay of 15 seconds is added before starting to check the low-pressure accumulator and shear pressure differential.

[0056] After executing the "One-key Cut Off" program, the One-key Cut Off program display area shows the position of each valve. If the valve position is correct, it will be green, otherwise it will be red and the PLC will control the sound and light alarm to sound. After pressing the alarm mute button, the alarm will be canceled.

[0057] Cut open the control process:

[0058] When the "One-key cut off" function has been used during the drilling process and the "One-key cut on" function is required after the problem is solved, after pressing the "One-key cut on" button, the PLC receives the "One-key cut on" program:

[0059] The high-pressure valve solenoid valve closing electromagnet is turned on and delayed for 5 seconds. The solenoid valve closing electromagnet is energized and reversed, controlling the high-pressure valve to reverse to the closed position. The high-pressure valve open position signal is fed back to the PLC, and the PLC transmits the high-pressure valve position signal to the touch screen for displaying the valve position;

[0060] After the high-pressure valve solenoid valve is turned on and the timing starts for 3 seconds, the pressure relief valve solenoid valve opening electromagnet is turned on and the time is delayed for 5 seconds. The solenoid valve opening electromagnet is energized and reversed, controlling the pressure relief valve to reverse to the open position. The pressure relief valve opening position signal is fed back to the PLC, and the PLC transmits the pressure relief valve position signal to the touch screen for displaying the valve position.

[0061] After the pressure relief valve solenoid valve is turned on and timing starts for 3 seconds, the low-pressure valve solenoid valve opening electromagnet is turned on and delayed for 5 seconds. The solenoid valve opening electromagnet is energized and reversed to control the low-pressure valve to the open position. The low-pressure valve open position signal is fed back to the PLC, and the PLC transmits the low-pressure valve position signal to the touch screen for displaying the valve position.

[0062] After the low-pressure valve solenoid is connected and a three-second timer begins, the shear valve solenoid is energized and a five-second delay is applied. The solenoid then switches direction, controlling the shear valve to the open position. The shear valve open position signal is fed back to the PLC, which transmits it to the touch screen to display the valve position. The electrical control system then controls the BOP gate to open, completing the one-touch shear opening procedure.

[0063] After executing the "One-key cut open" program, the one-key cut open program display area shows the position of each valve. If the valve position is correct, it will be green, otherwise it will be red and the PLC will control the sound and light alarm to alarm. After pressing the alarm mute button, the alarm will be canceled.

[0064] Emergency stop control process:

[0065] In case of failure or misoperation, the "Emergency Stop" function can be used. After pressing the emergency stop button, the PLC receives the "Emergency Stop" program:

[0066] The low-pressure valve solenoid valve opening electromagnet is turned on and delayed for 5 seconds. The solenoid valve opening electromagnet is energized and reversed, controlling the low-pressure valve to reverse to the closed position. The low-pressure valve opening position signal is fed back to the PLC, and the PLC transmits the low-pressure valve position signal to the touch screen for displaying the valve position.

[0067] When the low-pressure valve solenoid valve is turned on, the high-pressure valve solenoid valve closing electromagnet is turned on and delayed for 5 seconds. The solenoid valve closing electromagnet is energized and reversed to control the high-pressure valve to reverse to the closed position. The high-pressure valve open position signal is fed back to the PLC, and the PLC transmits the high-pressure valve position signal to the touch screen to display the valve position.

[0068] When the low-pressure valve and the high-pressure valve are closed at the same time, the oil supply to the blowout preventer opening and closing pipelines stops, and the blowout preventer immediately stops, completing the emergency stop operation control procedure.

[0069] After executing the "emergency stop operation" program, the emergency stop operation program display area shows the position of each valve. If the valve position is correct, it will be green, otherwise it will be red and the PLC will control the sound and light alarm to alarm. After pressing the alarm mute button, the alarm will be canceled.

[0070] Overpressure relief control process:

[0071] When the safety relief valve of the hydraulic system fails to work properly due to an abnormality, causing the pressure to continue to rise and reach the set value, the "overpressure relief" program will be activated:

[0072] The pressure relief valve solenoid valve opening electromagnet is turned on and delayed for 5 seconds. The solenoid valve opening electromagnet is energized and reversed, controlling the pressure relief valve to reverse to the open position. The pressure relief valve opening position signal is fed back to the PLC, and the PLC transmits the pressure relief valve position signal to the touch screen for displaying the valve position.

[0073] After the pressure relief valve solenoid valve is turned on and the timing starts for 3 seconds, the high-pressure valve solenoid valve opening electromagnet is turned on and delayed for 5 seconds. The solenoid valve opening electromagnet is energized and reversed to control the high-pressure valve to the open position. At this time, the hydraulic oil in the high-pressure accumulator is unloaded back to the oil tank, completing the "overpressure relief" procedure.

[0074] It should be noted that both the low-pressure valve and the high-pressure valve are 70 MPa pneumatic ball valves with position feedback signals, the shear valve is a hydraulic rotary valve with position feedback signals, and the solenoid valve is an explosion-proof solenoid valve.

[0075] The preferred embodiments of the present application disclosed above are intended only to help illustrate the present application. The optional embodiments do not describe all details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made based on the content of the embodiments of the present application. This application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the embodiments of the present application, so that those skilled in the art can better understand and utilize the present application. This application is limited only by the claims and their full scope and equivalents.

Claims

1. A high-low pressure dual-circuit surface blowout preventer shear control method, characterized in that: Including shear closing control process and shear opening control process; Shear shutoff control process: After receiving the "one-button shear shutoff" signal, the PLC simultaneously controls the low-pressure valve to open and the pressure relief valve to close. After a delay of T1, the shear valve is controlled to the closed position. The hydraulic oil in the low-pressure accumulator pushes the shear gate to start closing. After a delay of T2, it is determined whether the first requirement for executing the first action is met. If so, the first action is executed. If not, the determination is continued until the second requirement for executing the first action is met, and then the first action is executed. The first action is to immediately open the high-pressure valve to allow the high-pressure accumulator hydraulic oil to flow into the shear shutoff pipeline. Shear opening control process: When the "one-button shear closing" function has been used during the drilling process and the "one-button shear opening" function is required after the problem is resolved, after receiving the "one-button shear opening" signal, the PLC controls the high-pressure valve to close, the pressure relief valve to open, the low-pressure valve to open, and the shear valve to open position in sequence, thereby releasing the high-pressure hydraulic oil in the shear pipeline and controlling the shear gate to open. The time interval for the above valve actions is T1; The first requirement is that the pressure difference between the low-pressure accumulator and the shear valve is less than 0.5 MPa 15 seconds after the PLC detects the shear valve closed position signal; the second requirement is that the timing is full 20 seconds after the PLC detects the shear valve closed position signal.

2. The high-low pressure dual-circuit surface blowout preventer shear control method according to claim 1, characterized in that: It also includes the initialization control process, specifically: After receiving the initialization instruction, the PLC switches each valve to the set position. Each valve realizes the switching of the switch position by controlling the solenoid valve. The electromagnet of each solenoid valve is energized for 5 seconds and then de-energized. After the valve is in place, the corresponding position sensor will feed back the valve position signal to the PLC. At the same time, the PLC transmits the valve position signal to the touch screen for display. If the valve position is correct, it will be green, otherwise it will be red and the PLC controls the sound and light alarm to alarm. Among them, during the initialization process, the low-pressure valve is opened, the high-pressure valve is closed, the shear valve is opened, and the pressure relief valve is closed.

3. The high-low pressure dual-circuit surface blowout preventer shear control method according to claim 2, characterized in that: It also includes the overpressure relief control process, specifically: After receiving the differential pressure relief command, the PLC controls the pressure relief valve to open, and after a delay of T1, controls the high-pressure valve to open, unloading the high-pressure oil, and unloading the hydraulic oil in the high-pressure accumulator back to the tank to protect the hydraulic system.

4. The high-low pressure dual-circuit surface blowout preventer shear control method according to claim 3, characterized in that: It also includes the emergency stop control process, specifically: Upon receiving the emergency stop command, the PLC controls the low-pressure valve to close and the high-pressure valve to close at the same time, the blowout preventer open and close pipelines stop supplying oil, the blowout preventer immediately stops, and the emergency stop operation control procedure is completed.

5. The high-low pressure dual-circuit surface blowout preventer shear control method according to claim 4, characterized in that: When the PLC operates each valve in the order of instructions, it delays the power-on time of each valve to ensure that each valve is switched in place. After the delay time ends, the solenoid valves are powered off in turn. At the same time, the PLC collects the position switch signals of each valve and displays them on the touch screen. If the valve position is correct, the corresponding valve indicator light is "green", otherwise it is red. If there is an error in the valve position, the corresponding indicator light turns red and the system sound and light alarm is activated at the same time.

6. The high-low pressure dual-circuit surface blowout preventer shear control method according to claim 5, characterized in that: The T1 value is 3 seconds, and the T2 value is 15 seconds.

7. The high-low pressure dual-circuit surface blowout preventer shear control method according to claim 6, characterized in that: The low-pressure valve and the high-pressure valve are both 70MPa pneumatic ball valves with position feedback signals.

8. The high-low pressure dual-circuit surface blowout preventer shear control method according to claim 7, characterized in that: The shear valve is a hydraulic rotary valve with a position feedback signal, and the solenoid valve is an explosion-proof solenoid valve.

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