Composite electro-hydraulic underwater control system testing method

Abstract

The invention provides a composite electro-hydraulic underwater control system test method, which comprises the following steps of ensuring interface matching and equipment installation completion; hydraulic oil is prepared, and the energy accumulator pressure is confirmed; calculating underwater cable direct current resistance, an insulation value and an underwater optical fiber light loss receiving qualified value, and ensuring that a test result accords with a receiving standard; confirming that the communication between the main control station and the underwater routing module is normal; a hydraulic supply pump is adjusted to an automatic mode, a low-pressure working condition is established, and an isolating valve is closed after requirements are met; the state of the valve is confirmed, the underwater communication loss logic is cut off and bypassed, and finally a hydraulic loop of the hydraulic power unit is opened to supply to the electromagnetic valve; the consistency of underwater communication, hydraulic supply, control signal transmission and valve execution states is verified by switching SEMA / B channels and LP1 / LP2 loops. According to the method, the dependence on underwater operation resources is reduced, the reliability of the system under the multi-fault complex working condition can be more comprehensively verified, the test risk is reduced, and the test period is greatly shortened while the project quality is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ocean engineering, and in particular to a test method for a composite electro-hydraulic underwater control system. BACKGROUND

[0002] An underwater control system is an important part of offshore oil and gas exploitation due to its advantages of high efficiency, low cost, reliability, etc. It is usually divided into two parts: an above-water control part and an underwater production equipment part. The above-water control part includes a main control system (MCS), an electric power unit (EPU), and a hydraulic power unit (HPU). The underwater system facilities include an underwater central manifold, a Christmas tree, a subsea control module (SCM), and a subsea routing module, etc. These devices communicate and transmit hydraulic pressure through a umbilical cable, and the main control system realizes remote control and monitoring of the underwater equipment. Further processing and export are carried out relying on a jacket platform or a floating facility. After the umbilical cable is replaced, the underwater control system should ensure that the pre-production process is controllable and has emergency shutdown measures. Therefore, after installation, the underwater control system first needs to test the functional integrity of the underwater control system.

[0003] However, the existing test method for the underwater control system is affected by the complex marine environment, resulting in a long test period, high operation risk, and increased dependence on underwater resources (such as divers or remotely operated underwater vehicles). In particular, in sea areas without underwater unmanned remote carrier operation conditions (such as steel cylinder type underwater production systems, high turbidity, and silt deposition sea areas), in order to reduce the risks brought by complex environment operation, reduce the number of equipment plugging and power-off, and alleviate the problems of long test period and discontinuous operation, the existing test method needs to be optimized to make the joint test of the underwater control system safer, more efficient, and more reliable. SUMMARY

[0004] The main technical problem to be solved by the present application is the long test period, high operation risk, and increased dependence on underwater resources of the existing test method for the underwater control system. In order to overcome the above-mentioned defects existing in the prior art, a test method for a composite electro-hydraulic underwater control system joint test is provided.

[0005] The technical solution adopted by the present application to solve its technical problems is: A test method for a composite electro-hydraulic underwater control system joint test, comprising the following steps: S1. Before formal testing, ensure that the hydraulic, communication, and electrical interfaces in the subsea control system are correctly matched, and that the subsea manifold, Christmas tree, and umbilical cable have been installed and the corresponding installation inspection report has been obtained; S2. Calculate the amount of hydraulic oil required for the test. Based on the calculated results, prepare the hydraulic oil required to meet the system's operating requirements and add it to the hydraulic power unit's oil supply tank, ensuring that the hydraulic oil volume in the supply tank can meet the test requirements. Also, calculate the hydraulic oil pressure drop after a single wellhead subsea hydraulic control valve opening and closing operation. Verify that the pre-charge pressures of the high- and low-pressure accumulators meet the requirements of the technical specifications to ensure that the hydraulic system can continue to operate for a period of time after a pressure supply failure. S3. Calculate the DC resistance, insulation value, and underwater optical fiber loss acceptance values ​​of the underwater cable to ensure that the test results meet the acceptance standards. Using the umbilical cable as the transmission medium, activate the underwater control module and underwater routing module through the electrical power supply unit, establish dual-channel communication between the master control station and the underwater control system, calculate the hydrostatic pressure of the underwater manifold, and ensure that the pressure value transmitted to the master control station by the relevant underwater pressure transmitter is within the acceptable range. Verify that the underwater high and low pressure hydraulic supply and hydraulic power unit output pressure values ​​are within the acceptable range. S4. First, when the underwater optical fiber and digital subscriber line communications are normal, disconnect the optical fiber communication with the underwater routing module to confirm that the control station and the underwater routing module are communicating normally; then restore the first optical fiber communication and disconnect the digital subscriber line cable and the second optical fiber to confirm that the master control station and the underwater routing module are communicating normally; finally, restore the second optical fiber and disconnect the first optical fiber to confirm that the master control station and the underwater routing module are communicating normally; S5. Use the local control panel of the hydraulic power unit to adjust the high-pressure and low-pressure hydraulic supply pumps to automatic operation mode, establish underwater low-pressure test conditions, and confirm that the output pressure meets the requirements of the technical specifications. Then, close the underwater hydraulic supply isolation valve of the surface umbilical terminal unit. S6. Confirm that the status of relevant underwater valves is within the acceptable range as required by the test plan and the master control station valve status. Shut down and bypass the underwater communication loss logic. Finally, open the hydraulic power unit hydraulic circuit supply solenoid valve to confirm the normal operation of the underwater control system. S7. Start the subsea control module and Christmas tree to test the subsea control system. Open the subsea hydraulic supply and return line isolation valves on the surface umbilical cable terminal unit. Set the SEMA channel on the subsea electronic module on the HMI of the master control station for subsea communication and control. Verify that the pressure in the LP1 circuit of the hydraulic power unit system meets the specifications. Shut down and depressurize the output pump of the LP2 circuit of the hydraulic power unit system. Use the master control station to open the subsea hydraulic control valves one by one according to the well opening sequence. Simultaneously record the opening time of the subsea hydraulic control valves on the HMI and the actual opening time of the underwater observation valves. Verify that the actual status of the hydraulic control valves on the master control station and the Christmas tree are within the acceptable range. S8. Start the hydraulic power unit system LP2 loop output pump, raise the LP2 hydraulic circuit supply pressure to the operating pressure, close the LP1 loop output pump and depressurize, use the master control station to close the underwater hydraulic control valves one by one, record the human-machine interface HMI underwater hydraulic control valve closing time and the underwater observation valve actual closing time, confirm that the master control station and the actual state of the Christmas tree hydraulic control valve are within the qualified range; S9. Set the SEMB channel on the master control station human-machine interface HMI interface for underwater communication and control, use the master control station to open the underwater hydraulic control valves one by one, record the human-machine interface HMI underwater hydraulic control valve opening time and the underwater observation valve actual opening time, confirm that the master control station and the actual state of the Christmas tree hydraulic control valve are within the qualified range; S10. Start the hydraulic power unit system LP1 loop output pump, raise the LP1 hydraulic circuit supply pressure to the operating pressure, close the LP2 loop output pump and depressurize, use the master control station to close the underwater hydraulic control valves one by one, record the human-machine interface HMI underwater hydraulic control valve closing time and the underwater observation valve actual closing time, confirm that the master control station and the actual state of the Christmas tree hydraulic control valve are within the qualified range; S11. After the underwater control system test is completed, the underwater hydraulic and chemical agent system is depressurized, high pressure, low pressure and oil return pipeline hydraulic oil is taken from the umbilical cable terminal unit discharge port, and the cleanliness is detected to meet the specification requirements; set the logic off alarm value to the pre-production state value on the master control station, and verify that the underwater valve state meets the pre-production needs one by one, and clean the site.

[0006] Further, after closing the underwater hydraulic supply isolation valve of the surface umbilical cable terminal unit in step S5, the pressure is maintained for at least 15 minutes, and the pressure drop during the pressure maintaining period meets the test specification requirements.

[0007] Further, between steps S1 and S2, a temporary hose and filter tool should be used to fill hydraulic oil into the hydraulic power unit oil return tank, open the ball valve and three-way electromagnetic valve of the oil return tank series washing circuit to complete the hydraulic oil series washing, and finally adjust the three-way electromagnetic valve and use the hydraulic delivery pump to transfer the hydraulic oil to the oil supply tank.

[0008] Further, between steps S2 and S3, the optical fiber short-circuit test cap should be removed before the underwater umbilical cable terminal unit is launched, and the optical fiber tester is used to measure the optical fiber loop loss from the master control station to the underwater routing module.

[0009] Further, between steps S5 and S6, the chemical agent system should also be pressure maintained, a pressure maintaining path from the chemical agent sled to the Christmas tree hydraulic control valve is established using the chemical agent pump, the pressure maintaining time is at least 15 minutes, and after the pressure drop meets the technical specification requirements, S6 is performed.

[0010] Further, between the steps S5 to S6, the high pressure of the underwater control system loop should be established and the action simulation test of the downhole safety valve SCSSV should be carried out. The pressure establishment is referred to S5, the action simulation test process is referred to S7-S10, the liquid flying line on the tree side needs to be installed on the PARKING panel during the SCSSV test, and after the SCSSV action simulation test is completed, S6 is carried out, and all the tests related to the SCSSV test are simulated valve switching, and the actual action of the SCSSV is strictly prohibited.

[0011] Further, between the steps S6 to S7, each subsystem should be checked, including: power distribution system, hydraulic distribution system, communication control system, chemical agent system, central control system, fire fighting system, umbilical cable transmission system and tree system, to ensure the normal function of each subsystem.

[0012] Further, between the steps S7 to S8, the underwater control system should be tested for power failure, the output voltage of the electrical power unit to the underwater routing module is disconnected, the state of the hydraulic control valve is observed underwater without change, it is confirmed that the function of the underwater control system is normal, and the test process is recorded.

[0013] Further, between the steps S10 to S11, the underwater control system should be tested for hydraulic failure. Since the LP1 and LP2 hydraulic switching during the valve action test of S8-S10 has been verified, the state of the valve does not change when one-way hydraulic failure, in the open state of the hydraulic control valve, LP1 and LP2 loop is depressurized, underwater hydraulic control valve is observed, after the hydraulic pressure is restored, it is confirmed that the valve state does not change, and the test process is recorded.

[0014] Further, between the steps S10 to S11, the underwater control system should be tested for emergency shutdown ESD logic and stability. After the simulation of underwater emergency shutdown ESD logic test is completed, it is confirmed that the underwater control system runs for at least 12 hours, the underwater temperature, pressure, liquid level sensor, underwater routing module, underwater control module communication has no interruption, the underwater hydraulic control valve is normally operated through the master control station, and the test process is recorded. After the stability test meets the specification requirements, S11 is carried out.

[0015] The beneficial effects of the present application are: 1. The method combines the underwater umbilical cable optical fiber test with the optical jumper test, and pre-tests the underwater optical fiber loop before the underwater control system joint test, more comprehensively verifies whether the underwater optical fiber loop interface matching and optical loss meet the design requirements, avoids the second diving of the diver to remove the optical fiber loop protection cap, reduces the influence of sea conditions and the demand for underwater operation, improves the test efficiency and enhances the continuity of the test process; compared with the optical fiber test data of the factory test report and the umbilical cable pre-debugging, the underwater optical fiber loop optical loss and performance can be more comprehensively verified.

[0016] 2. The method switches the SEMA / B communication channel, alternately supplies pressure and pressure relief hydraulic power unit system LP1 / LP2 hydraulic circuit, verifies the consistency of underwater communication, hydraulic supply, control signal transmission and valve execution state, and realizes multi-system joint test.

[0017] 3. In the valve action test process, the method introduces hydraulic and power failure scenarios in advance, and inserts fault simulation test in the valve action test, not only realizes multi-system joint test, but also more comprehensively simulates real failure scenarios, improves test efficiency and system reliability, and significantly reduces underwater operation amount and risk.

[0018] 4. The method integrates optical fiber and digital subscriber line redundancy, optical fiber redundancy test, verifies the reliability of underwater communication, reduces the risk of equipment wear and aging, and more comprehensively verifies the reliability of the system under complex working conditions.

[0019] 5. The method can realize higher integration of the whole underwater control system test, reduce the dependence on underwater operation resources, more comprehensively verify the reliability of the system under complex working conditions, reduce the test risk, greatly shorten the test period while ensuring the engineering quality. BRIEF DESCRIPTION OF DRAWINGS

[0020] The present application will be further described below in conjunction with the drawings and examples.

[0021] Fig. 1 The present application is an underwater control system composition diagram; Fig. 2 The present application is an underwater hydraulic control valve test flow chart. DETAILED DESCRIPTION

[0022] The present application will be further described below in conjunction with the drawings and examples. The illustrative embodiments of the present application and the description are used to explain the present application, but are not limited to the present application.

[0023] Embodiment: a composite electro-hydraulic underwater control system test method as shown in Figs. 1-2

[0024] Referring to Fig. 1 and Fig. 2 , the present application discloses a composite electro-hydraulic underwater control system test method, comprising the following steps: First step: Ensure that the hydraulic, communication, electrical interface in the underwater control system is correctly matched before formal testing, and that the underwater manifold, Christmas tree, umbilical cable and the like have been installed and the corresponding installation inspection report has been obtained. At the same time, calculate the amount of hydraulic oil required for testing, use temporary hoses, filters and other tooling to fill the hydraulic oil into the hydraulic power unit return tank, open the ball valve and three-way solenoid valve of the return tank series washing circuit to complete the hydraulic oil series washing, and finally transfer the hydraulic oil to the oil supply tank by adjusting the three-way solenoid valve and using the hydraulic delivery pump. At the same time, calculate the hydraulic oil pressure drop for completing a single wellhead underwater hydraulic control valve switching operation, check the pre-charging pressure of the high and low pressure accumulators, and ensure that the hydraulic system can operate for a period of time as required by the technical specification.

[0025] Second step: Remove the optical fiber short-circuit test cap before the underwater umbilical cable terminal unit is launched, measure the optical loss from the main control station to the underwater routing module using an optical fiber tester, calculate the underwater cable DC resistance, insulation value, and underwater optical fiber optical loss receiving qualified value, and ensure that the test results meet the receiving standard. With the umbilical cable as the transmission medium, activate the underwater control module, underwater routing module and other key equipment through the electrical power supply unit, establish double-channel communication between the main control station and the underwater control system, calculate the hydrostatic pressure of the underwater manifold, ensure that the pressure value transmitted to the main control station by the underwater related pressure transmitter is within the qualified range, and check the underwater high and low pressure hydraulic supply and hydraulic power unit output pressure value one by one and within the qualified range. This method removes the optical fiber short-circuit test cap on the underwater umbilical cable terminal unit in advance, measures the optical fiber loop loss from the main control to the underwater routing module using an optical fiber tester, combines the underwater optical fiber test with the optical fiber test, and prepositions the underwater optical fiber loop test before the underwater control system joint test, which more comprehensively verifies whether the underwater optical fiber loop interface matching and optical loss meet the design requirements, avoids the need for divers to dive again to remove the optical fiber loop protection cap, reduces the influence of sea conditions and the demand for underwater operation, improves test efficiency and enhances the continuity of the test process.

[0026] ​Third step: First, under the condition of normal underwater optical fiber and digital subscriber line communication, disconnect the 2-way optical fiber communication between the master control station switch and the underwater routing module, and confirm that the master control station and the underwater routing module communicate normally. Then restore the first optical fiber communication, and disconnect the digital subscriber line cable and the second optical fiber, and confirm that the master control station and the underwater routing module communicate normally. Finally, restore the second optical fiber and disconnect the first optical fiber, and confirm that the master control station and the underwater routing module communicate normally.

[0027] The method introduces a fiber and digital subscriber line communication fault switching mechanism in the optical fiber communication redundancy test, reduces the frequent charging and discharging of electronic modules and the number of fiber plugging, verifies the reliability of underwater communication, and effectively reduces the risks of wear, end face pollution, and aging.

[0028] Fourth step: Adjust the high and low pressure hydraulic supply pumps to automatic operation mode through the local control panel of the hydraulic power unit, establish the underwater high and low pressure test working condition, and when the loop pressure meets the test outline requirements, close the underwater hydraulic supply isolation valve of the topside umbilical cable terminal unit, and maintain pressure for at least 15 minutes, and the pressure drop during the pressure maintaining period meets the specification book requirements. Then carry out the action simulation test of the downhole safety valve SCSSV, the action simulation test process is referred to the sixth step to the tenth step, and the liquid flying line on the Christmas tree side needs to be installed on the PARKING panel during the test. After the SCSSV action simulation test, the fifth step can be carried out, and the subsequent tests involving SCSSV all use simulated valve switching, and the actual action of SCSSV is strictly prohibited. Finally, the chemical agent system is pressure maintained, the chemical agent pump is used to establish the pressure maintaining path from the chemical agent skid to the liquid control valve before the Christmas tree, and the pressure maintaining time is at least 15 minutes. When the pressure drop meets the technical specification book.

[0029] Fifth step: First, adjust the state of the underwater related valves to meet the test outline requirements, and confirm that the state of the master control station and the underwater liquid control valve is within the qualified range. Second, open the hydraulic loop supply solenoid valve of the hydraulic power unit, and close the bypass of the underwater communication loss logic, confirm that the underwater control system is running normally, and finally check each subsystem, including: power distribution system, hydraulic distribution system, communication control system, chemical agent system, central control system, fire fighting system, umbilical cable transmission system and Christmas tree system, to ensure that each subsystem works normally.

[0030] Step 6: Start the subsea control module and the Christmas tree as required to perform the subsea control system test, open the subsea hydraulic supply isolation valve of the surface umbilical terminal unit, set the SEMB channel on the HMI interface of the master control station to perform subsea communication and control, confirm that the pressure of the hydraulic power unit system LP1 loop meets the specification requirements, shut down and depressurize the output pump of the hydraulic power unit system LP2 loop, use the master control station to sequentially open the subsea hydraulic control valves according to the well opening sequence, and record the HMI subsea hydraulic control valve opening time and the actual opening time of the subsea observation valve, and confirm that the actual state of the master control station and the Christmas tree hydraulic control valve is within the qualified range.

[0031] Step 7: Perform a power failure test on the subsea control system, disconnect the electrical power unit to either of the two subsea routing module output voltages, and observe that the state of the hydraulic control valve does not change, disconnect the electrical power unit to both of the two subsea routing module output voltages, and confirm that the subsea control system is working normally, and record the test process.

[0032] Step 8: Start the output pump of the hydraulic power unit system LP2 loop, raise the LP2 hydraulic loop supply pressure to the operating pressure, and close and depressurize the output pump of the LP1 loop, use the master control station to sequentially close the subsea hydraulic control valves, and record the HMI subsea hydraulic control valve closing time and the actual closing time of the subsea observation valve, and confirm that the actual state of the master control station and the Christmas tree hydraulic control valve is within the qualified range.

[0033] Step 9: Set the SEMB channel on the HMI interface of the master control station to perform subsea communication and control, use the master control station to sequentially open the subsea hydraulic control valves, and record the HMI subsea hydraulic control valve opening time and the actual opening time of the subsea observation valve, and confirm that the actual state of the master control station and the Christmas tree hydraulic control valve is within the qualified range.

[0034] Step 10: Start the output pump of the hydraulic power unit system LP1 loop, raise the LP1 hydraulic loop supply pressure to the operating pressure, and close and depressurize the output pump of the LP2 loop, use the master control station to sequentially close the subsea hydraulic control valves, and record the HMI subsea hydraulic control valve closing time and the actual closing time of the subsea observation valve, and confirm that the actual state of the master control station and the Christmas tree hydraulic control valve is within the qualified range. Then perform a hydraulic failure test on the subsea control system, close and depressurize the output pump of the LP2 loop, observe the closing of the subsea hydraulic control valve, and confirm that the valve state does not change after the hydraulic pressure is restored, and record the test process.

[0035] The method switches the SEMA / B communication channel, alternately supplies and depressurizes the hydraulic power unit system LP1 / LP2 hydraulic loop, and verifies the consistency of subsea communication, hydraulic supply, control signal transmission and valve execution state.

[0036] The method introduces hydraulic and power failure scenarios in advance in the valve action test process, and inserts failure simulation tests in the valve action test, which not only realizes multi-system linkage test, but also more comprehensively simulates real failure scenarios, improves test efficiency and system reliability, and significantly reduces underwater operation amount and risk.

[0037] Tenth step: Perform emergency shutdown ESD logic and stability test on the underwater control system. After the simulation of underwater emergency shutdown ESD logic test is completed, confirm that the underwater control system runs for 12 hours, the communication of key equipment such as underwater temperature, pressure, liquid level sensor, underwater routing module and underwater control module is uninterrupted, the Christmas tree hydraulic valve can be normally operated through the master control station, and the test process is recorded.

[0038] Twelfth step: After the underwater control system test is completed, depressurize the underwater hydraulic and chemical agent system, take high pressure, low pressure and oil return pipeline hydraulic oil from the umbilical cable terminal unit discharge port for cleanliness detection to meet the specification requirements. Set the logic shutdown alarm value to the pre-production state value at the master control station, and check the underwater valve state one by one to meet the pre-production needs, and clean up the site.

[0039] The technical method of the present application can realize higher integration of the whole underwater control system test, reduce the dependence on underwater operation resources, more comprehensively verify the reliability of the system under complex working conditions with multiple failures, reduce the test risk, and greatly shorten the test period while ensuring the engineering quality.

[0040] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiment still belongs to the scope of the technical solution of the present application.

Claims

1. A test method for a combined electro-hydraulic underwater control system, characterized in that: The following steps are involved: S1. Before formal testing, ensure that the hydraulic, communication, and electrical interfaces in the subsea control system are correctly matched, and that the subsea manifold, Christmas tree, and umbilical cable have been installed and the corresponding installation inspection report has been obtained; S2. Calculate the amount of hydraulic oil required for the test. Based on the calculated results, prepare the hydraulic oil required to meet the system's operating requirements and add it to the hydraulic power unit's oil supply tank, ensuring that the hydraulic oil volume in the supply tank can meet the test requirements. Also, calculate the hydraulic oil pressure drop after a single wellhead subsea hydraulic control valve opening and closing operation. Verify that the pre-charge pressures of the high- and low-pressure accumulators meet the requirements of the technical specifications to ensure that the hydraulic system can continue to operate for a period of time after a pressure supply failure. S3. Calculate the DC resistance, insulation value, and underwater optical fiber loss acceptance values ​​of the underwater cable to ensure that the test results meet the acceptance standards. Using the umbilical cable as the transmission medium, activate the underwater control module and underwater routing module through the electrical power supply unit, establish dual-channel communication between the master control station and the underwater control system, calculate the hydrostatic pressure of the underwater manifold, and ensure that the pressure value transmitted to the master control station by the relevant underwater pressure transmitter is within the acceptable range. Verify that the underwater high and low pressure hydraulic supply and hydraulic power unit output pressure values ​​are within the acceptable range. S4. First, under normal underwater optical fiber and digital subscriber line communication, disconnect the optical fiber communication with the underwater routing module and confirm that the control station and the underwater routing module are communicating normally; Then restore the first optical fiber communication, disconnect the digital subscriber line cable and the second optical fiber, and confirm that the communication between the master control station and the underwater routing module is normal; Finally, restore the second optical fiber and disconnect the first optical fiber to confirm that the communication between the master control station and the underwater routing module is normal; S5. Use the local control panel of the hydraulic power unit to adjust the high-pressure and low-pressure hydraulic supply pumps to automatic operation mode, establish underwater low-pressure test conditions, and confirm that the output pressure meets the requirements of the technical specifications. Then, close the underwater hydraulic supply isolation valve of the surface umbilical terminal unit. S6. Confirm that the status of relevant underwater valves is within the acceptable range as required by the test plan and the master control station valve status. Shut down and bypass the underwater communication loss logic. Finally, open the hydraulic power unit hydraulic circuit supply solenoid valve to confirm the normal operation of the underwater control system. S7. Start the subsea control module and Christmas tree to test the subsea control system. Open the subsea hydraulic supply and return line isolation valves on the surface umbilical cable terminal unit. Set the SEMA channel on the subsea electronic module on the HMI of the master control station for subsea communication and control. Verify that the pressure in the LP1 circuit of the hydraulic power unit system meets the specifications. Shut down and depressurize the output pump of the LP2 circuit of the hydraulic power unit system. Use the master control station to open the subsea hydraulic control valves one by one according to the well opening sequence. Simultaneously record the opening time of the subsea hydraulic control valves on the HMI and the actual opening time of the underwater observation valves. Verify that the actual status of the hydraulic control valves on the master control station and the Christmas tree are within the acceptable range. S8. Start the LP2 circuit output pump of the hydraulic power unit system and increase the LP2 hydraulic circuit supply pressure to the operating pressure. Simultaneously, shut down the LP1 circuit output pump and relieve the pressure. Use the master control station to close the subsea hydraulic control valves one by one. Simultaneously record the closing time of the subsea hydraulic control valves on the human-machine interface (HMI) and the actual closing time of the underwater observation valves to confirm that the actual status of the hydraulic control valves on the master control station and the Christmas tree are within the acceptable range. S9. Set up the SEMB channel on the master control station's human-machine interface (HMI) for underwater communication and control. Use the master control station to open the underwater hydraulic control valves one by one. Simultaneously record the HMI underwater hydraulic control valve opening time and the actual opening time of the underwater observation valves to confirm that the actual status of the master control station and the Christmas tree hydraulic control valves are within the acceptable range. S10. Start the LP1 circuit output pump of the hydraulic power unit system and increase the LP1 hydraulic circuit supply pressure to the operating pressure. Simultaneously, shut down the LP2 circuit output pump and relieve the pressure. Use the master control station to close the subsea hydraulic control valves one by one. Simultaneously record the closing time of the subsea hydraulic control valves on the human-machine interface (HMI) and the actual closing time of the underwater observation valves to confirm that the actual status of the hydraulic control valves on the master control station and the Christmas tree are within the acceptable range. S11. After the underwater control system test is completed, the underwater hydraulic and chemical systems are depressurized. The hydraulic oil of the high-pressure, low-pressure, and return oil pipelines is collected at the discharge port of the surface umbilical cable terminal unit. The cleanliness is tested to ensure that it meets the requirements of the specification. At the main control station, the logical shutdown alarm value is set to the pre-commissioning status value, and the status of each underwater valve is verified to meet the pre-commissioning requirements. The site is then cleaned.

2. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: In step S5, after closing the underwater hydraulic supply isolation valve of the surface umbilical cable terminal unit, the pressure is maintained for at least 15 minutes, and the pressure drop during the pressure maintenance period meets the requirements of the test specification.

3. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: Between steps S1 and S2, a temporary hose and filter tool should be used to add hydraulic oil to the hydraulic power unit return tank, open the ball valve and three-way solenoid valve of the return tank wash circuit to complete the hydraulic oil wash, and finally adjust the three-way solenoid valve and use a hydraulic delivery pump to transfer the hydraulic oil to the supply tank.

4. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: Between steps S2 and S3, the optical fiber short-circuit test cap should be removed before the underwater umbilical cable terminal unit is launched into the water, and the optical fiber loop loss from the master control station to the underwater routing module should be measured using a fiber optic tester.

5. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: Between steps S5 and S6, a pressure maintenance test should be performed on the chemical system. A chemical pump should be used to establish a pressure maintenance path from the chemical skid to the front of the Christmas tree hydraulic control valve. The pressure maintenance time should be at least 15 minutes. S6 should be performed after the pressure drop meets the requirements of the technical specifications.

6. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: Between steps S5 and S6, pressure should be established in the high-pressure circuit of the underwater control system and a downhole safety valve SCSSV action simulation test should be performed. For pressure establishment, refer to S5, and for the action simulation test process, refer to S7-S10. During the SCSSV test, the Christmas tree side liquid flying line must be installed on the PARKING panel. After the SCSSV action simulation test is completed, S6 should be performed. All SCSSV tests must use simulated valve switching, and actual SCSSV action is strictly prohibited.

7. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: Between steps S6 and S7, each subsystem should also be checked, including: power distribution system, hydraulic distribution system, communication control system, chemical agent system, central control system, fire protection system, umbilical cable transmission system and Christmas tree system, to ensure that each subsystem functions normally.

8. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: Between steps S7 and S8, an underwater control system should also be subjected to an electrical failure test, by disconnecting the output voltage from the electrical power unit to the underwater routing module, observing underwater that the status of the hydraulic control valve remains unchanged, confirming that the underwater control system functions normally, and recording the test process.

9. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: A hydraulic fault test should also be performed on the underwater control system between steps S10 and S11. Since the hydraulic switching of LP1 and LP2 during the valve action test S8-S10 has verified that the status of the valve in one hydraulic failure path remains unchanged, when the hydraulic control valve is open, the LP1 and LP2 circuits are depressurized, and the underwater hydraulic control valve is observed to close. After the hydraulic pressure is restored, it is confirmed that the valve status remains unchanged, and the test process is recorded.

10. The test method for a combined electro-hydraulic underwater control system according to claim 1, characterized in that: Between steps S10 and S11, the underwater control system should also be subjected to an emergency shutdown ESD logic test and a stability test. After the simulated underwater emergency shutdown ESD logic test is completed, it is confirmed that the underwater control system has been running for at least 12 hours, the underwater temperature, pressure, liquid level sensors, underwater routing module, and underwater control module have communicated without interruption, the underwater hydraulic control valve is operated normally through the main control station, and the test process is recorded. After the stability test meets the requirements of the specification, S11 is carried out.

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