Well control assembly device for lightweight underwater operation

Abstract

A well control assembly device for lightweight underwater operations, comprising a well control assembly frame (5). A main passage unit (1) in communication with a Christmas tree is connected to the well control assembly frame; an annular circulation unit (2) used for managing injection of a well-killing fluid or a workover fluid and controlling wellhead pressure is connected to the main passage unit; a chemical injection unit (3) is further connected to the main passage unit; a control cabin structure unit (4) is connected to the well control assembly frame; the control cabin structure unit is in communication with the annular circulation unit and the chemical injection unit, so as to control the annular circulation unit, the chemical injection unit and the main passage unit. The device implements high-precision pressure control of the main passage unit and efficient chemical injection by means of the annular circulation unit, the chemical injection unit and the control cabin structure unit, thereby improving the safety and efficiency of underwater well control operations, and also greatly reducing operation costs.

Description

Well control assembly device for underwater light operation TECHNICAL FIELD

[0001] The present application belongs to the field of offshore oil engineering, and particularly relates to a well control assembly device for underwater light operation. BACKGROUND

[0002] At present, with the continuous increase of the development of offshore oil and gas resources, more and more subsea wells are put into use, and the maintenance and stimulation of deepwater subsea oil wells become an important operation task. The traditional oil well intervention operation is completed through a semi-submersible platform, which has the disadvantages of high operation cost and low efficiency. The traditional well control technology has complex operation process and high operation cost under the harsh underwater environment.

[0003] The new oil well light intervention operation can be completed through a special work ship. The light intervention operation relies on light intervention equipment and does not need to deploy a riser, so the operation cost is greatly reduced. In this process, effective well control operation is the key to ensure operation safety and improve production efficiency.

[0004] Therefore, it is urgent to design a well control assembly device for underwater light operation to solve the above-mentioned problems of low efficiency and low reliability of the existing well control assembly device. TECHNICAL PROBLEM

[0005] The traditional oil well intervention operation is completed through a semi-submersible platform, which has the disadvantages of high operation cost and low efficiency. The traditional well control technology has complex operation process and high operation cost under the harsh underwater environment. SOLUTION

[0006] To solve the technical problems of low efficiency and low reliability of the existing well control assembly device mentioned in the background, a well control assembly device for underwater light operation is provided to solve the above problems.

[0007] To achieve the above-mentioned purpose, the specific technical scheme of the well control assembly device for underwater light operation of the present application is as follows:

[0008] A well control assembly device for underwater light operation, comprising a well control assembly frame, a main channel unit connected with the Christmas tree is connected on the well control assembly frame, an annulus circulation unit for managing the injection of kill fluid or workover fluid and controlling the wellhead pressure is connected on the main channel unit, a chemical agent injection unit is also connected on the main channel unit, a control bin structure unit is connected on the well control assembly frame, the control bin structure unit is communicated with the annulus circulation unit and the chemical agent injection unit, and the annulus circulation unit, the chemical agent injection unit and the main channel unit are controlled.

[0009] Further, the main channel unit comprises a Christmas tree connecting device, the Christmas tree connecting device is fixedly connected with the well control assembly frame, and the main channel unit is connected with the Christmas tree through the Christmas tree connecting device;

[0010] The main channel unit is provided with a lower blowout preventer connecting body for connecting the lower blowout preventer assembly at one end away from the Christmas tree connecting device, and is sequentially provided with a first cross connecting device and a second cross connecting device in the direction away from the Christmas tree connecting device. The two sides of the first cross connecting device, the second cross connecting device and the lower blowout preventer connecting body are respectively provided with a chemical agent injection interface and an annular space injection interface. The chemical agent injection interface is communicated with the chemical agent injection unit, and the annular space injection interface is communicated with the annular space circulating unit, so that the annular space circulating unit and the chemical agent injection unit are communicated with the main channel unit.

[0011] Further, the Christmas tree connecting device comprises an upper connecting body, the upper connecting body is flange-connected with the first cross connecting device, and a lower connecting body is flange-connected with one end of the upper connecting body away from the first cross connecting device. The Christmas tree connecting device is connected with the Christmas tree through the lower connecting body.

[0012] The lower connecting body is provided with a trapezoidal protrusion, and the side surface of the upper connecting body is provided with a connecting locking clamp. The locking transmission shaft is connected with the locking clamp. The trapezoidal protrusion on the lower connecting body is locked with the cap end of the Christmas tree by rotating the locking transmission shaft.

[0013] Further, the main channel unit is provided with a first isolation valve and a second isolation valve,

[0014] One end of the first isolation valve is connected with the lower blowout preventer connecting body, and the other end of the first isolation valve away from the lower blowout preventer connecting body is connected with the second cross connecting device, so as to control the opening and closing of the pipeline between the second cross connecting device and the lower blowout preventer connecting body. One end of the second isolation valve is connected with the first cross connecting device, and the other end of the second isolation valve away from the first cross connecting device is connected with the second cross connecting device, so as to control the opening and closing of the pipeline between the first cross connecting device and the second cross connecting device.

[0015] Further, the first isolation valve is connected with a valve body driver, and the first isolation valve comprises an isolation valve body, the isolation valve body is flange-connected with the valve body driver, and the isolation valve body is provided with an isolation valve gate plate for controlling the opening and closing of the isolation valve body,

[0016] The valve body driver comprises a hydraulic cylinder, the piston is slidably connected in the hydraulic cylinder, one end of the piston is connected with the isolation valve gate plate, the other end of the piston away from the isolation valve gate plate is fixedly connected with the output end of the hydraulic cylinder, the output end of the hydraulic cylinder drives the piston to move, so as to control the movement of the isolation valve gate plate, and further control the opening and closing of the isolation valve body.

[0017] Further, the main channel unit is provided with a full seal gate and a shear gate, the full seal gate and the shear gate are in communication with each other, and the shear gate and the full seal gate are located between the first isolation valve and the second isolation valve, so as to provide emergency sealing for the main channel unit.

[0018] One end of the full seal gate is connected with the flange of the first isolation valve, the other end of the full seal gate is connected with the flange of the shear gate, one end of the shear gate is connected with the flange of the full seal gate, and the other end of the shear gate is connected with the flange of the second isolation valve.

[0019] Further, the annulus circulation unit comprises a well killing fluid injection pipeline for injecting well killing fluid, one end of the well killing fluid injection pipeline is in communication with the control chamber structure unit, the other end of the well killing fluid injection pipeline is in communication with the main channel unit, and a first annulus isolation valve is installed on the well killing fluid injection pipeline to control the opening and closing of the well killing fluid injection pipeline.

[0020] The annulus circulation unit further comprises an annulus circulation pipeline for controlling wellhead pressure, one end of the annulus circulation pipeline is in communication with the control chamber structure unit, the other end of the annulus circulation pipeline is in communication with the main channel unit, a second annulus isolation valve is installed on the annulus circulation pipeline to control the opening and closing of the annulus circulation pipeline, and an annulus pressure regulating valve is installed on the annulus circulation pipeline to regulate the pressure of the annulus circulation pipeline.

[0021] Further, the control chamber structure unit comprises an accumulator group, the accumulator group is detachably connected with the well control assembly frame, and the accumulator group is in communication with the annulus circulation unit and the chemical agent injection unit respectively, so as to provide hydraulic power for the main channel unit, the annulus circulation unit and the chemical agent injection unit.

[0022] The control chamber structure unit comprises an underwater control module, the underwater control module is fixedly connected with the well control assembly frame, and the underwater control module is electrically connected with the annulus circulation unit and the chemical agent injection unit respectively, so as to control the annulus circulation unit, the chemical agent injection unit and the main channel unit.

[0023] The underwater control module further comprises a pressure sensor and a flow sensor, the pressure sensor and the flow sensor are respectively installed on the annulus circulation unit, the chemical agent injection unit and the main channel unit, so as to detect the pipeline pressure and flow of the annulus circulation unit, the chemical agent injection unit and the main channel unit respectively.

[0024] Further, the chemical agent injection unit comprises a chemical agent injection pipeline, one end of the chemical agent injection pipeline is in communication with the control chamber structure unit, the other end of the chemical agent injection pipeline is in communication with the main channel unit, and a chemical agent injection valve is installed on the chemical agent injection pipeline to control the injection amount of the chemical agent and the opening and closing of the chemical agent injection pipeline.

[0025] The chemical agent injection pipeline is connected with an agent injection pipeline four-way joint to connect the ethylene glycol injection pipeline and the chemical injection umbilical to the chemical agent injection pipeline.

[0026] Further, the ROV control panel is fixedly connected to the well control assembly frame to control the annular circulation unit, the chemical agent injection unit and the main channel unit. Advantages

[0027] The underwater light operation well control assembly device has the following advantages:

[0028] The annular circulation unit, the chemical agent injection unit and the control bin structure unit realize high-precision pressure control of the main channel unit and efficient chemical agent injection, improve the safety and efficiency of underwater well control operation, and greatly reduce the operation cost.

[0029] The ROV control panel provides an interface with the ROV, realizes seamless control design with the ROV, and enables the operator to remotely control the key components of the well control system. DETAILED DESCRIPTION

[0030] Fig. 1 is a schematic diagram of the underwater light operation well control assembly device;

[0031] Fig. 2 is a schematic diagram of the overall structure of the underwater light operation well control assembly device;

[0032] Fig. 3 is a sectional view of the main channel unit.

[0033] Marked description in the figure: 1, main channel unit; 101, Christmas tree connecting device; 102, lower blowout preventer connecting body; 103, first bridging device; 104, second bridging device; 105, first isolation valve; 106, second isolation valve; 107, valve body driver; 108, full seal ram; 109, shear ram; 1011, upper connecting body; 1012, lower connecting body; 1013, connecting locking clamp; 1014, locking transmission shaft; 1015, locking nut; 1051, isolation valve body; 1052, isolation valve ram; 1071, hydraulic cylinder; 1072, piston; 1073, spring positioning sleeve; 1074, driver reset spring; 1075, transmission lead screw; 1076, ROV transmission nut; 1077, thrust ball bearing; 2, annulus circulation unit; 201, well killing fluid injection pipeline; 2011, first annulus isolation valve; 2012, switching valve; 202, annulus circulation pipeline; 2021, second annulus isolation valve; 2022, annulus pressure regulating valve; 3, chemical agent injection unit; 301, chemical agent injection pipeline; 3011, chemical agent injection valve; 3012, agent injection pipeline cross; 3013, check valve; 3014, chemical agent flow sensor; 4, control bin structure unit; 401, accumulator group; 402, standby accumulator group; 403, safety valve group; 404, underwater control module; 405, underwater module fixing bottom plate; 5, well control assembly frame; 6, ROV control panel. Embodiments of the present application

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0035] A person of ordinary skill in the art can understand that, although some of the embodiments herein include certain features but not other features included in other embodiments, the combination of features of different embodiments means to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0036] The underwater light-duty well control assembly device of the present application is described below with reference to FIG. 1 to FIG. 3.

[0037] The traditional well control technology has complex operation procedures and high operation cost under the harsh environmental conditions of the water.

[0038] Therefore, the application provides a well control assembly device for underwater light operation, as shown in Figure 1, which comprises a well control assembly frame 5, a main channel unit 1 connected with the Christmas tree and communicated with the main channel unit 1, an annulus circulation unit 2 for managing injection of well killing fluid or workover fluid and controlling wellhead pressure, a chemical injection unit 3 connected with the main channel unit 1, and a control bin structure unit 4 connected with the well control assembly frame 5 and communicated with the annulus circulation unit 2 and the chemical injection unit 3, so as to control the annulus circulation unit 2, the chemical injection unit 3 and the main channel unit 1. Specifically, the device integrates pressure control and chemical injection mechanism, provides firm physical support through the well control assembly frame 5, thereby improving the safety and efficiency of underwater well control operation.

[0039] As shown in Figure 2, the main channel unit 1 comprises a Christmas tree connecting device 101 fixedly connected with the well control assembly frame 5, realizing connection and locking with the underwater Christmas tree tubing hanger, and the main channel unit 1 is connected with the Christmas tree through the Christmas tree connecting device 101.

[0040] The main channel unit 1 is provided with a lower blowout preventer connecting body 102 for connecting the lower blowout preventer assembly at one end away from the Christmas tree connecting device 101, and a first crossover device 103 and a second crossover device 104 are sequentially arranged in the direction away from the Christmas tree connecting device 101 of the main channel unit 1, and chemical injection interfaces and annulus injection interfaces are respectively arranged on both sides of the first crossover device 103, the second crossover device 104 and the lower blowout preventer connecting body 102, the chemical injection interfaces are communicated with the chemical injection unit 3, and the annulus injection interfaces are communicated with the annulus circulation unit 2, so that the annulus circulation unit 2 and the chemical injection unit 3 are communicated with the main channel unit 1.

[0041] As shown in Figure 2 and Figure 3, the Christmas tree connecting device 101 comprises an upper connecting body 1011 flange-connected with the first crossover device 103, a lower connecting body 1012 flange-connected with the upper connecting body 1011 at one end away from the first crossover device 103, and the Christmas tree connecting device 101 is connected with the Christmas tree through the lower connecting body 1012; a trapezoidal protrusion is arranged on the lower connecting body 1012, a connecting locking clamp 1013 is arranged on the side surface of the upper connecting body 1011, a locking transmission shaft 1014 is connected with the connecting locking clamp 1013, the locking transmission shaft 1014 is rotated to lock the trapezoidal protrusion on the lower connecting body 1012 with the cap end of the Christmas tree, so as to fix the lower connecting body 1012 with the Christmas tree, and the locking transmission shaft 1014 is reversely rotated to separate the lower connecting body 1012 from the Christmas tree, thereby facilitating installation and disassembly.

[0042] Preferably, the upper connecting body 1011 is fixedly connected with a locking nut 1015, and the locking transmission shaft 1014 is screwed with the locking nut 1015, so as to realize accurate transmission of the locking transmission shaft 1014.

[0043] The main channel unit 1 is provided with a first isolation valve 105 and a second isolation valve 106. One end of the first isolation valve 105 is connected with the lower blowout preventer connecting body 102, and the other end of the first isolation valve 105 away from the lower blowout preventer connecting body 102 is connected with the second jumper 104, so as to control opening and closing of the pipeline between the second jumper 104 and the lower blowout preventer connecting body 102. One end of the second isolation valve 106 is connected with the first jumper 103, and the other end of the second isolation valve 106 away from the first jumper 103 is connected with the second jumper 104, so as to control opening and closing of the pipeline between the first jumper 103 and the second jumper 104.

[0044] As shown in FIGS. 2 and 3, the first isolation valve 105 is connected with a valve body driver 107. The first isolation valve 105 comprises an isolation valve body 1051, which is flange-connected with the valve body driver 107. The isolation valve body 1051 is internally provided with an isolation valve shutter 1052 for controlling opening and closing of the isolation valve body 1051.

[0045] The valve body driver 107 comprises a hydraulic cylinder 1071, which is internally slidably connected with a piston 1072. One end of the piston 1072 is connected with the isolation valve shutter 1052, and the other end of the piston 1072 away from the isolation valve shutter 1052 is fixedly connected with an output end of the hydraulic cylinder 1071. The output end of the hydraulic cylinder 1071 drives the piston 1072 to move, so as to control movement of the isolation valve shutter 1052, and further control opening and closing of the isolation valve body 1051. It should be noted that the second isolation valve 106 has the same structure as the first isolation valve 105, and will not be described here.

[0046] Preferably, the valve body driver 107 further comprises a spring positioning sleeve 1073, which is threadedly connected with the piston 1072. A driver return spring 1074 is installed between the spring positioning sleeve 1073 and the hydraulic cylinder 1071, so as to drive the spring positioning sleeve 1073, thereby realizing resetting of the isolation valve shutter 1052.

[0047] Preferably, the other end of the piston 1072 away from the isolation valve shutter 1052 is threadedly connected with a transmission screw 1075, so as to increase ROV mechanical control on the basis of hydraulic drive of the valve body driver 107, and realize the purpose of double-line control. Specifically, the spring positioning sleeve 1073 is provided with an ROV transmission nut 1076. The transmission screw 1075 can be driven by the ROV, so as to drive the ROV transmission nut 1076 to move, thereby driving the piston 1072 to move, and realizing opening and closing of the isolation valve shutter 1052.

[0048] Preferably, the spring positioning sleeve 1073 is provided with a thrust ball bearing 1077, which is sleeved on the transmission screw 1075 and cooperates with the end of the transmission screw 1075 to bear the axial thrust of the transmission screw 1075.

[0049] The main channel unit 1 is provided with a full sealing gate plate 108 and a shearing gate plate 109, which are in communication with each other and are located between the first isolation valve 105 and the second isolation valve 106 for emergency sealing of the main channel unit 1. One end of the full sealing gate plate 108 is connected with the flange of the first isolation valve 105, and the other end of the full sealing gate plate 108 is connected with the flange of the shearing gate plate 109. One end of the shearing gate plate 109 is connected with the flange of the full sealing gate plate 108, and the other end of the shearing gate plate 109 is connected with the flange of the second isolation valve 106. Specifically, the shearing gate plate 109 is used to shear the tool string or the wire rope in an emergency, and after the shearing gate plate 109 is closed, the full sealing gate plate 108 seals the main channel unit 1.

[0050] The annulus circulation unit 2 comprises a well killing fluid injection pipeline 201 for injecting well killing fluid or workover fluid. One end of the well killing fluid injection pipeline 201 is in communication with the control chamber structure unit 4, and the other end of the well killing fluid injection pipeline 201 is in communication with the main channel unit 1. A first annulus isolation valve 2011 is installed on the well killing fluid injection pipeline 201 to control the opening and closing of the well killing fluid injection pipeline 201. Specifically, the first annulus isolation valve 2011 is in a normally closed state and is opened after connecting the well killing umbilical to control the opening and closing of the well killing injection pipeline.

[0051] Optionally, a switching valve 2012 is installed upstream of the connection between the well killing fluid injection pipeline 201 and the main channel unit 1. The switching valve 2012 is hydraulically controlled and can also be controlled by an ROV to control the opening and closing between the main channel unit 1 and the well killing fluid injection pipeline 201.

[0052] The annulus circulation unit 2 further comprises an annulus circulation pipeline 202 for controlling the wellhead pressure. One end of the annulus circulation pipeline 202 is in communication with the control chamber structure unit 4, and the other end of the annulus circulation pipeline 202 is in communication with the main channel unit 1. A second annulus isolation valve 2021 is installed on the annulus circulation pipeline 202 to control the opening and closing of the annulus circulation pipeline 202. An annulus pressure regulating valve 2022 is installed on the annulus circulation pipeline 202 to regulate the pressure of the annulus circulation pipeline 202. Specifically, the annulus pressure regulating valve 2022 can freely adjust the opening degree to maintain the pressure at the output end of the pipeline within a predetermined range, and can also prevent water hammer phenomenon and protect equipment.

[0053] The control cabin structure unit 4 comprises an accumulator group 401, which is detachably connected with the well control assembly frame 5, and is communicated with the annular circulation unit 2 and the chemical agent injection unit 3 respectively, so as to provide hydraulic power for the main channel unit 1, the annular circulation unit 2 and the chemical agent injection unit 3, and to control the valves and the gate plates by hydraulic pressure. As preferred, the control cabin structure unit 4 is additionally provided with a standby accumulator group 402, which is also detachably connected with the well control assembly frame 5 and communicated with the annular circulation unit 2 and the chemical agent injection unit 3. When the accumulator group 401 fails to provide hydraulic power, the standby accumulator group 402 provides hydraulic power for the valves and the gate plates.

[0054] Optionally, the accumulator group 401 is connected with a safety valve group 403, which is threadedly connected with the accumulator group 401, so as to protect the accumulator group 401 and the whole hydraulic system.

[0055] As preferred, the accumulator group 401 and the standby accumulator group 402 are fixed on the well control assembly frame 5 by a clamp, so as to facilitate the installation, dismounting and replacement.

[0056] The control cabin structure unit 4 comprises an underwater control module 404, which is fixedly connected with the well control assembly frame 5 and electrically connected with the annular circulation unit 2 and the chemical agent injection unit 3 respectively, so as to control the annular circulation unit 2, the chemical agent injection unit 3 and the main channel unit 1. Specifically, the valves and the gate plates can be controlled by electrical connection.

[0057] The underwater control module 404 further comprises a pressure sensor and a flow sensor, which are installed on the annular circulation unit 2, the chemical agent injection unit 3 and the main channel unit 1 respectively, so as to detect the pipeline pressure and flow of the annular circulation unit 2, the chemical agent injection unit 3 and the main channel unit 1 respectively.

[0058] As preferred, the well control assembly frame 5 is threadedly connected with an underwater module fixing bottom plate 405, which is threadedly connected with the underwater control module 404, so as to fix the underwater control module 404 on the well control assembly frame 5.

[0059] As preferred, pressure sensors are installed on the first cross-over device 103 and the second cross-over device 104 and electrically connected to the underwater control module 404 for detecting the pressure in the main passage unit 1; pressure sensors and flow sensors are installed on the well killing injection pipeline and electrically connected to the underwater control module 404 for detecting the pressure and flow on the well killing injection pipeline, and similarly, pressure sensors and flow sensors can be provided on any pipeline that needs to be monitored in the device and electrically connected to the underwater control module 404, which can be detected.

[0060] The chemical agent injection unit 3 comprises a chemical agent injection pipeline 301, one end of the chemical agent injection pipeline 301 is in communication with the control bin structure unit 4, the other end of the chemical agent injection pipeline 301 away from the control bin structure unit 4 is in communication with the main passage unit 1, and a chemical agent injection valve 3011 is installed on the chemical agent injection pipeline 301 to control the amount of agent injection and the opening and closing of the chemical agent injection pipeline 301.

[0061] The chemical agent injection pipeline 301 is connected with a chemical agent injection pipeline cross 3012 to connect the ethylene glycol injection pipeline and the chemical injection umbilical to the chemical agent injection pipeline 301.

[0062] As preferred, a check valve 3013 is installed on the chemical agent injection pipeline 301 to prevent backflow of the chemical agent.

[0063] As preferred, a chemical agent flow sensor 3014 is installed on the chemical agent injection pipeline 301, the chemical agent flow sensor 3014 is installed on the chemical agent injection pipeline 301 by screw thread and is electrically connected to the underwater control module 404 for detecting the flow of the agent injection.

[0064] As preferred, the well control assembly frame 5 is fixedly connected with an ROV control panel 6 for the ROV to mechanically control the annular circulation unit 2, the chemical agent injection unit 3 and the main passage unit 1, in particular, when the hydraulic valve of the device fails, the ROV is used to mechanically control the valve to open or close.

[0065] The annular circulation unit 2, the chemical agent injection unit 3 and the control bin structure unit 4 realize high-precision pressure control of the main passage unit 1 and efficient chemical agent injection, improve the safety and efficiency of underwater well control operation, and greatly reduce the operation cost.

[0066] The ROV control panel 6 provides an interface with the ROV, realizes seamless control design with the ROV, and enables the operator to remotely control the key components of the well control system.

[0067] The well control assembly frame 5 of the present application provides a solid physical support for the device, ensuring stability and reliability in harsh underwater environments.

[0068] Obviously, the above-mentioned embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation manners of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and also impossible to enumerate all the implementation manners. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application. Industrial applicability

[0069] The well control assembly frame of the present application provides a solid physical support for the device, ensuring stability and reliability in harsh underwater environments.

Claims

1. A well control assembly for underwater lightweight operations, characterized in that, The system includes a well control assembly frame, a main channel unit connected to the well production tree, an annular circulation unit for managing the injection of kill fluid or workover fluid and controlling wellhead pressure, a chemical injection unit, and a control chamber structure unit connected to the well control assembly frame. The control chamber structure unit is connected to the annular circulation unit and the chemical injection unit, thereby controlling the annular circulation unit, the chemical injection unit, and the main channel unit.

2. The underwater lightweight well control assembly according to claim 1, characterized in that, The main channel unit includes a tree connection device, which is fixedly connected to the well control assembly frame. The main channel unit is connected to the tree through the tree connection device. The main channel unit has a lower blowout preventer connector for connecting to the lower blowout preventer assembly at the end away from the tree connection device. A first bridging device and a second bridging device are sequentially provided in the direction away from the tree connection device of the main channel unit. Chemical injection interface and annular injection interface are respectively opened on both sides of the first bridging device, the second bridging device, and the lower blowout preventer connector. The chemical injection interface is connected to the chemical injection unit, and the annular injection interface is connected to the annular circulation unit, so that the annular circulation unit and the chemical injection unit are both connected to the main channel unit.

3. The underwater lightweight well control assembly according to claim 2, characterized in that, The Christmas tree connection device includes an upper connecting body, which is connected to the flange of the first bridging device. The flange at the end of the upper connecting body away from the first bridging device is connected to a lower connecting body. The Christmas tree connection device is connected to the Christmas tree through the lower connecting body. The lower connector has a trapezoidal protrusion, and the upper connector has a connecting locking clamp on its side. The connecting locking clamp is connected to a locking drive shaft. Rotating the locking drive shaft locks the trapezoidal protrusion on the lower connector with the cap end of the oil well tree.

4. The underwater lightweight well control assembly according to claim 2, characterized in that, The main channel unit is equipped with a first isolation valve and a second isolation valve. One end of the first isolation valve is connected to the lower blowout preventer connector, and the other end of the first isolation valve away from the lower blowout preventer connector is connected to the second bridging device to control the opening and closing of the pipeline between the second bridging device and the lower blowout preventer connector. One end of the second isolation valve is connected to the first bridging device, and the other end of the second isolation valve, away from the first bridging device, is connected to the second bridging device, so as to control the opening and closing of the pipeline between the first bridging device and the second bridging device.

5. The underwater lightweight well control assembly according to claim 4, characterized in that, A valve body actuator is connected to the first isolation valve. The first isolation valve includes an isolation valve body, which is flange-connected to the valve body actuator. An isolation valve gate is provided inside the isolation valve body to control the opening and closing of the isolation valve body. The valve body actuator includes a hydraulic cylinder, in which a piston is slidably connected. One end of the piston is connected to the gate of the isolation valve, and the end of the piston away from the gate of the isolation valve is fixedly connected to the output end of the hydraulic cylinder. The output end of the hydraulic cylinder drives the piston to move, thereby controlling the movement of the gate of the isolation valve and thus controlling the opening and closing of the isolation valve body.

6. The underwater lightweight well control assembly according to claim 4, characterized in that, The main channel unit is equipped with a full-sealing gate and a shearing gate, which are interconnected. Both the shearing gate and the full-sealing gate are located between the first isolation valve and the second isolation valve, so that the main channel unit can be closed in an emergency. One end of the fully sealed gate is connected to the flange of the first isolation valve, the end of the fully sealed gate away from the first isolation valve is connected to the flange of the shear gate, one end of the shear gate is connected to the flange of the fully sealed gate, and the end of the shear gate away from the fully sealed gate is connected to the flange of the second isolation valve.

7. The underwater lightweight well control assembly according to claim 1, characterized in that, The annular circulation unit includes a kill fluid injection pipeline for injecting kill fluid or workover fluid. One end of the kill fluid injection pipeline is connected to the control chamber structure unit, and the end of the kill fluid injection pipeline away from the control chamber structure unit is connected to the main channel unit. A first annular isolation valve is installed on the kill fluid injection pipeline to control the opening and closing of the kill fluid injection pipeline. The annular circulation unit also includes an annular circulation pipeline for controlling wellhead pressure. One end of the annular circulation pipeline is connected to the control chamber structure unit, and the end of the annular circulation pipeline away from the control chamber structure unit is connected to the main channel unit. A second annular isolation valve is installed on the annular circulation pipeline to control the opening and closing of the annular circulation pipeline. An annular pressure regulating valve is installed on the annular circulation pipeline to regulate the pressure of the annular circulation pipeline.

8. The underwater lightweight well control assembly according to claim 1, characterized in that, The control chamber structural unit includes an accumulator group, which is detachably connected to the well control assembly frame. The accumulator group is connected to the annular circulation unit and the chemical injection unit respectively, so as to provide hydraulic power to the main channel unit, the annular circulation unit and the chemical injection unit. The control chamber structural unit includes a subsea control module, which is fixedly connected to the well control assembly frame. The subsea control module is electrically connected to the annular circulation unit and the chemical injection unit to control the annular circulation unit, the chemical injection unit and the main channel unit. The underwater control module also includes pressure sensors and flow sensors, which are installed on the annular circulation unit, the chemical injection unit, and the main channel unit, respectively, to detect the pipeline pressure and flow rate of the annular circulation unit, the chemical injection unit, and the main channel unit.

9. The underwater lightweight well control assembly according to claim 1, characterized in that, The chemical injection unit includes a chemical injection pipeline. One end of the chemical injection pipeline is connected to the control chamber structure unit, and the other end of the chemical injection pipeline away from the control chamber structure unit is connected to the main channel unit. A chemical injection valve is installed on the chemical injection pipeline to control the amount of chemical injected and the opening and closing of the chemical injection pipeline. A chemical injection pipeline four-way connector is connected to the chemical injection pipeline to connect the ethylene glycol injection pipeline and the chemical injection umbilical cable to the chemical injection pipeline.

10. The underwater lightweight well control assembly according to claim 1, characterized in that, The ROV control panel is fixedly connected to the well control assembly frame for the ROV to mechanically control the annulus circulation unit, chemical injection unit, and main channel unit.

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