CN101798909B - Offshore floating drilling platform drill string heave compensation device - Google Patents

Abstract

The invention discloses a drilling column heave compensation device of a marine floating type drilling platform. A composite hydraulic cylinder is adopted as a heave compensation hydraulic cylinder in a crown block heave compensation device; the high-pressure hydraulic oil output by a hydraulic pump flows into a rodless cavity of an inner cylinder and a rod cavity of an outer cylinder of the composite compensation hydraulic cylinder by a compensation control valve to provide controllable additional force for a piston rod of the outer cylinder; and the resultant force of the force and the hydraulic force acted by the rodless cavity of the outer cylinder of the compensation hydraulic cylinder provides support force to a crown block. The direction and magnitude of the additional force are controlled according to the platform heave motion, and the compensation effect of a heave compensation system is improved. A control unit transmits a control command to the hydraulic system according to the motion speed of the platform in the vertical direction, wherein the motion speed is obtained by detection, drives a piston of the compensation hydraulic cylinder to push the crown block to move and compensates the heave motion of the platform so that the crown block, a traveling block and a large hook are in a static state in the vertical direction relative to the well bottom in the allowable range.

Description

Offshore floating drilling platform drill string heave compensation device

technical field

The invention relates to a hydraulic control system characterized by electro-hydraulic control technology, in particular to a heave compensation device for a drill string of an ocean drilling platform.

Background technique

With the depletion of land resources, the strategic vision of the world's economic development is focused on the ocean, and the development of marine technology and high-tech equipment is particularly important. In the field of petroleum, with the development of China's economy, especially the rapid development of the petrochemical and automobile industries as the pillar industries, the contradiction of insufficient supply of oil and natural gas has become increasingly prominent. In view of the depletion of onshore oil resources, marching into the deep sea has become an inevitable trend. At present, the maximum working water depth of offshore oil drilling rigs has exceeded 3000m, and will continue to develop in a deeper direction. Working in such water depth conditions requires more stringent requirements on all aspects of the drilling rig, and must also adapt to some special conditions faced in deep water conditions, and many equipment needs to be redesigned and developed.

Drill string heave compensation device is one of the essential equipment to ensure the safe operation of offshore drilling ships or semi-submersible drilling platforms and improve work efficiency and quality. The semi-submersible drilling platform and drilling pontoon used in deep-sea drilling will produce periodic heave motion under the action of waves, and make the drill string reciprocate up and down, causing changes in the drilling pressure at the bottom of the well, and even make the drill bit out of the bottom of the well. It affects the drilling efficiency, reduces the life of the drill bit and drill pipe, creates potential safety hazards in operation, and even leads to failure to drill and forced shutdown, resulting in huge economic losses. Therefore, in order to reduce downtime and reduce drilling costs, the floating drilling platform must take appropriate compensation measures for the heave movement of the drill string.

The hydraulic heave compensation system is most commonly used on offshore floating drilling platforms and has many forms. According to its power supply method, it can be divided into three forms: active, passive and semi-active.

The active heave compensation system has good compensation effect and strong adaptability, but due to the large mass of the drill string and frequent up and down reciprocating movements, a large amount of energy will be consumed in the compensation process.

The passive heave compensation system basically does not need the system to provide additional energy during the compensation process, and the system is simple, so it has been widely used, but the compensation effect is not very ideal, and there is a certain hysteresis phenomenon.

The semi-active heave compensation system can combine the advantages of both, but the system structure is more complicated and the manufacturing cost is higher.

Contents of the invention

The object of the present invention is to provide a heave compensation device for a floating offshore oil drilling platform to meet the performance requirements of offshore oil drilling.

In order to achieve the above purpose, the general idea of the present invention is to use a compound hydraulic cylinder as a heave compensation hydraulic cylinder in the heave compensation device of the crane. Lead the high-pressure hydraulic oil in the gas-hydraulic accumulator to the rodless chamber of the outer cylinder of the composite compensation hydraulic cylinder, so as to provide a hydraulic pressure to withstand the static load of the crane; the high-pressure hydraulic oil output by the hydraulic pump is passed through the compensation control valve Provide a controllable additional force to the rodless chamber of the inner cylinder of the composite compensation hydraulic cylinder and the rod chamber of the outer cylinder, thereby providing a controllable additional force to the piston rod of the outer cylinder, which is equal to the hydraulic pressure acting on the rodless chamber of the outer cylinder of the composite compensation hydraulic cylinder The combined force provides support to the crane.

The technical scheme adopted in the present invention is to improve on the basis of the conventional passive heave compensation device composed of a crown block, two heave compensation hydraulic cylinders, a rocker arm, a gas-liquid accumulator, and a traveling block, adding an acceleration sensor, Fuel tank, electric motor, hydraulic pump, hydraulic pump outlet check valve, compensation control valve, inner cylinder rodless cavity pressure sensor, outer cylinder rod cavity pressure sensor, bypass valve, speed limiting valve, fuel charge check valve, safety control valve, power failure protection valve and system control unit. The cylinder body of the composite compensation hydraulic cylinder is hinged to the derrick, the upper end of the piston rod is hinged to the crown block, and pressure sensors are installed on the rod chamber of the outer cylinder of the composite compensation hydraulic cylinder and the rodless chamber of the inner cylinder. The ratio of the plunger area of the inner cylinder to the working area of the rod chamber of the outer cylinder of the composite compensation hydraulic cylinder is 1:1. The inlet of the hydraulic pump is connected to the oil tank, and the outlet is connected to the P port of the compensation control valve through the check valve; the T port of the compensation control valve is connected to the oil tank; the B port of the compensation control valve is connected to the inner cylinder of the two composite compensation hydraulic cylinders without rods The A port of the compensation control valve is connected with the rod chamber of the outer cylinder of the two composite compensation hydraulic cylinders; one end of the bypass valve is connected with the rodless chamber of the inner cylinder of the two composite compensation hydraulic cylinders, and the other end is connected with the two composite compensation hydraulic cylinders. The outer cylinder of the compensation hydraulic cylinder is connected with the rod chamber; the A port of the speed limiting valve is connected with the rod chamber of the outer cylinder of the two composite compensation hydraulic cylinders, and the B port is connected with the A port of the compensation control valve; the A port of the hydraulic shut-off valve It is connected with the rodless chamber of the outer cylinder of the two composite compensation hydraulic cylinders, and the P port is connected with the A port of the power failure protection valve; the P port of the power failure protection valve is connected with the outlet of the gas-liquid converter, the oil supply check valve and the safety valve at the same time. The inlet of the control valve is connected; the other end of the gas-liquid converter is connected to the working gas cylinder through the gate valve; the working gas cylinder is connected to the deflation gate valve, and connected to the high-pressure gas cylinder through the gate valve; The inlet of the oil check valve and the outlet of the safety control valve are connected together and connected to the oil tank; the control unit is electrically connected to the control signal interface of the compensation control valve, bypass valve, power failure protection valve, and frequency conversion motor, and obtains the external cylinder The electric signal of the rod chamber pressure sensor, the rodless chamber pressure sensor of the inner cylinder and the acceleration sensor fixedly connected on the platform. The hydraulic pump is mechanically connected with the frequency conversion motor. The control unit is an industrial computer or single-chip microcomputer with analog-to-digital A/D and digital-to-analog D/A signal conversion functions.

Compared with the background technology, the present invention has the beneficial effects that:

1. The compensation hydraulic cylinder in the system adopts a composite structure. The high-pressure hydraulic oil in the gas-liquid converter bears the static load on the crane through the rodless cavity of the outer cylinder. The hydraulic pump is connected to the rodless cavity of the inner cylinder or the outer cylinder through the compensation control valve. The rod cavity is connected to overcome the dynamic load caused by the friction force and the pressure change of the working gas cylinder during the motion compensation process, thereby effectively limiting the extra energy consumption and improving the compensation effect.

2. When the system suddenly loses load, the piston rod of the composite compensation hydraulic cylinder will move upward quickly, and the flow out of the rod cavity of the outer cylinder will increase, but the speed limiting valve will limit the flow rate below a certain value, thus limiting the upward speed of the piston ; At the same time, the pressure in the rod chamber of the outer cylinder increases, pushing the hydraulic shut-off valve to change direction, cutting off the pressure channel between the gas-liquid converter and the composite compensation hydraulic cylinder; the pressure signal measured by the pressure sensor in the rod chamber of the outer cylinder exceeds Within the allowable range, the control unit immediately sends a control command to cut off the power supply of the power failure protection valve, making it in the closed state. Through the above three protection measures, avoid serious accidents caused by load loss.

3. A power-off protection valve is installed between the gas-liquid converter and the composite compensation hydraulic cylinder. When the system loses power supply for some reason, the power-off protection valve resets under the action of the spring, cutting off the accumulator and the composite hydraulic cylinder. The oil circuit between the hydraulic cylinders is compensated by the formula to avoid accidents.

4. The control unit can send instructions to the frequency conversion motor and compensation control valve according to the acceleration signal sent by the acceleration sensor installed on the drilling platform and the pressure signal of the compound compensation hydraulic cylinder, and control the flow to the rodless cavity of the compound compensation hydraulic cylinder. The flow of hydraulic oil reduces the impact of platform heave movement on the hook, thereby keeping the bottom hole pressure constant within a certain range.

Description of drawings

Fig. 1 is a structural schematic diagram of a drill string heave compensation device for an offshore floating drilling platform proposed according to the present invention.

Fig. 2 is a schematic diagram of the hydraulic system of the drill string heave compensation device for the offshore floating drilling platform proposed by the present invention.

In the figure: 1- traveling block, 2- compound compensation hydraulic cylinder, 3- derrick, 4- rocker arm, 5- crown block, 6- pulley, 7- crown block guide rail, 8- acceleration sensor, 9- oil tank, 10 -hydraulic pump, 11-frequency conversion motor, 12-hydraulic pump outlet check valve, 13-compensation control valve, 14-outer cylinder rod chamber pressure sensor, 15-inner cylinder rodless chamber pressure sensor, 16-bypass valve, 17-speed limiting valve, 18-hydraulic shut-off valve, 19-power failure protection valve, 20-gas-liquid converter, 21-first gate valve, 22-working gas cylinder, 23-second gate valve, 24-air pressure source, 25-third gate valve, 26-discharging gate valve, 27-fifth gate valve, 28-high-pressure gas cylinder, 29-refueling check valve, 30-safety control valve, 31-control unit.

Detailed ways

The present invention will be further described below in conjunction with drawings and embodiments.

As shown in the figure, the cylinder body of the composite compensation hydraulic cylinder 2 is hinged to the derrick 3, and the upper end of the piston rod is hinged to the crown block 5. A pressure sensor 14 is installed in the rod chamber of the outer cylinder of the composite compensation hydraulic cylinder 2. A pressure sensor 15 is installed on the rodless cavity. The ratio of the plunger area of the inner cylinder to the working area of the rod chamber of the outer cylinder of the composite compensation hydraulic cylinder is 1:1. The acceleration sensor 8 is fixedly connected to the platform; the inlet of the hydraulic pump 10 is connected to the fuel tank 9, and the outlet is connected to the P port of the compensation control valve 13 through the check valve 12; the T port of the compensation control valve 13 is connected to the fuel tank 9; the compensation control valve 13 The port B of the valve is connected with the rodless chamber of the inner cylinder of the two composite compensation hydraulic cylinders 2, the A port of the compensation control valve 13 is connected with the rod chamber of the outer cylinder of the two composite compensation hydraulic cylinders 2; one end of the bypass valve 16 is connected with the two The inner cylinder rodless chamber of the composite compensation hydraulic cylinder 2 is connected, and the other end is connected with the rod chamber of the outer cylinder of the two composite compensation hydraulic cylinders 2; the A port of the speed limiting valve 17 is connected to the outer cylinder of the two composite compensation hydraulic cylinders 2 The rod cavity is connected, the B port of the speed limiting valve 17 is connected with the A port of the compensation control valve 13; The A port of the electric protection valve 19 is connected; the P port of the power failure protection valve 19 is connected with the gas-liquid converter 20, the outlet of the oil supplement check valve 29 and the inlet of the safety control valve 30 at the same time; the other end of the gas-liquid converter 20 The first gate valve 21 and the second gate valve 23 are connected to the working gas cylinder 22; the working gas cylinder 22 is connected to the deflation gate valve 26, and is connected to the high-pressure gas cylinder 28 through the fifth gate valve 27; the high-pressure gas cylinder 28 is connected to the third gate valve 25 It is connected with the air pressure source 24; the inlet of the fuel supply check valve 29 is connected with the outlet of the safety control valve 30 and connected with the oil tank 9; the control unit 31 is connected with the compensation control valve 13, the bypass valve 16 and the power failure protection valve 19 , the control signal interface of the variable frequency motor 11 is electrically connected, and is connected with the electric signal of the outer cylinder rod chamber pressure sensor 14, the inner cylinder rodless chamber pressure sensor 15 and the acceleration sensor 8 fixedly connected on the platform. The hydraulic pump 10 is mechanically connected to an inverter motor 11 . The control unit 31 is an industrial computer or a single-chip microcomputer with analog-to-digital A/D and digital-to-analog D/A signal conversion functions. The high-pressure hydraulic oil in the gas-liquid converter 20 leads to the rodless chamber of the outer cylinder of the composite compensation hydraulic cylinder 2, providing a hydraulic pressure to withstand the static load of the crane; the hydraulic pump 10 communicates with the rodless chamber of the inner cylinder through the compensation control valve 13 Or the outer cylinder is communicated with the rod cavity to overcome the dynamic load caused by the friction force and the pressure change in the working gas cylinder 22 during the compensation process. The two ends of the bypass valve 16 are connected with the rodless chamber of the inner cylinder and the rod chamber of the outer cylinder of the composite compensation hydraulic cylinder 2. When the bypass valve 16 is turned on, the system can realize the function of passive compensation. The outer cylinder of compound compensating hydraulic cylinder 2 has a rod cavity connected to speed limiting valve 17 to prevent the piston rod of compound compensating hydraulic cylinder 2 from overshooting and overshooting due to drill pipe breaking off. The control port of the hydraulic shut-off valve 18 is connected with the rod cavity of the outer cylinder of the composite compensation hydraulic cylinder 2. When the piston rod moves upward at overspeed, the increased pressure pushes the hydraulic shut-off valve 18 to change direction, cutting off the gas-liquid converter 20 and Composite compensation for the connecting pipeline of the hydraulic cylinder 2 can avoid serious accidents. The power-off protection valve 19 is installed between the gas-liquid converter 20 and the compound compensation hydraulic cylinder 2, and automatically cuts off the oil circuit when the power is lost, and stops supplying oil to the compound compensation hydraulic cylinder 2.

The working principle of the present invention is as follows:

During normal operation, the power-off protection valve is in the lower conduction state when it is energized, and the hydraulic shut-off valve is in the lower conduction state under the action of the spring. The rod cavities are connected to support the static load on the crown block. If the bypass valve 16 is in the conduction state of the right position, the rodless chamber of the inner cylinder of the composite compensation hydraulic cylinder 2 communicates with the rod chamber of the outer cylinder, and the compensation function does not work. At this time, the system is a conventional passive heave compensation system. If the bypass valve 16 is in the disconnected state in the left position, the rodless chamber of the inner cylinder of the composite compensation hydraulic cylinder 2 is not connected to the rod chamber of the outer cylinder, which acts as a compensation. At this time, the system is a semi-active heave compensation system.

When the floating offshore drilling platform sinks with the waves, the derrick will descend with the composite compensation hydraulic cylinder 2, the elongation and elastic deformation of the drill string will be reduced, the load on the crown block 5 will be reduced, and the composite compensation hydraulic cylinder 2 will The piston rod is extended, the hydraulic oil of the gas-liquid converter 20 flows into the composite compensating hydraulic cylinder 2, and the pressure of the working gas cylinder 22 is reduced, which is balanced with the reduced crane load. The acceleration sensor 8 installed on the composite compensation hydraulic cylinder detects the motion acceleration of the platform, and transmits the signal to the control unit 31 . At the same time, the pressure signals of the two chambers detected by the pressure sensor 14 of the rod chamber of the outer cylinder and the pressure sensor 15 of the rodless chamber of the inner cylinder are also transmitted to the control unit 31 . The control unit 31 sends a control command to the compensation control valve 13 to move left according to the above-mentioned detected signals and according to the established control strategy, so that the P port communicates with the B port, the A port communicates with the T port, and the hydraulic pump 10 is connected to the composite valve. Oil is supplied to the rodless chamber of the compensation hydraulic cylinder 2, so that the pressure of the rodless chamber in the inner cylinder rises, offsetting the drop in bearing capacity caused by the pressure reduction of the working cylinder and the friction force of the piston rod protruding, and the rod chamber of the outer cylinder passes through The channel from port A to port T is connected with the oil tank to realize oil return, so that the crane 5 moves upward relative to the platform to maintain the absolute position unchanged, and at the same time the load rises to the original set value. During this process, the displacement of the spool to the left can be adjusted to change the flow area of the valve port, thereby controlling the flow to control the movement speed of the piston and improving the compensation effect of the system.

Conversely, when the floating offshore drilling platform rises with the waves, the derrick will rise with the compound compensation hydraulic cylinder 2, the elongation and elastic deformation of the drill string will increase, the load on the crown block 5 will increase, and the compound compensation hydraulic cylinder 2 will The piston rod retracts, the hydraulic oil in the hydraulic cylinder flows back to the gas-liquid converter 20, and the pressure of the working gas cylinder 22 increases to balance with the increased crane load. The acceleration sensor 8 installed on the cylinder body of the composite compensating hydraulic cylinder 2 detects the motion acceleration of the platform, and transmits the signal to the control unit 31 . At the same time, the pressure signals of the two chambers detected by the pressure sensor 14 of the rod chamber of the outer cylinder and the pressure sensor 15 of the rodless chamber of the inner cylinder are also transmitted to the control unit 31 . The control unit 31 sends a control command to the compensation control valve 13 to move right according to the above-mentioned detected signals and according to the established control strategy, so that the P port communicates with the A port, the B port communicates with the T port, and the hydraulic pump 10 is connected to the composite valve. Compensation hydraulic cylinder 2. The outer cylinder has a rod cavity to supply oil, so that the pressure of the outer cylinder has a rod cavity to increase, which offsets the increase in the carrying capacity and the friction force of the piston rod retraction caused by the pressure increase of the working cylinder, and the inner cylinder has no rod. The chamber communicates with the oil tank through the channel from port B to port T to realize the oil return, so that the crane 5 moves down relative to the platform to maintain the absolute position, and at the same time the load drops to the original set value. During this process, the displacement of the spool to the right can be adjusted to change the flow area of the valve port, thereby controlling the flow to control the movement speed of the piston and improving the compensation effect of the system.

When the load of the system changes, the pressure of the working gas cylinder 22 can be adjusted to maintain the force balance of the piston rod of the compound compensating hydraulic cylinder 2 . When the system load decreases, the working gas cylinder 22 communicates with the vent gate valve 26, and the pressure of the working gas cylinder decreases through deflation; when the system load increases, the working gas cylinder 22 communicates with the high-pressure gas cylinder 28, and the high-pressure gas Inflation of the cylinder increases the pressure of the working cylinder.

When the system suddenly loses load due to accidents such as drill pipe breakage, the piston rod of the composite compensation hydraulic cylinder 2 will move upward rapidly, and the flow out of the rodless cavity of the outer cylinder will increase, but the speed limiting valve 17 will limit the flow rate below a certain value. One value, thereby limiting the upward speed of the piston; at the same time, the pressure in the rod chamber of the outer cylinder increases, pushing the hydraulic shut-off valve 18 to change direction, and cutting off the pressure channel between the gas-liquid converter 20 and the composite compensation hydraulic cylinder 2; When the pressure signal measured by the cylinder rod cavity pressure sensor 14 exceeds the allowable range, the control unit 31 immediately sends a control command to cut off the power supply of the power failure protection valve 19, making it in a closed state. Through the above three protection measures, avoid serious accidents caused by load loss.

When the system loses power supply for some reason, the power failure protection valve 20 resets under the action of the spring, cutting off the oil circuit between the gas-liquid converter 20 and the composite compensation hydraulic cylinder 2, preventing accidents from happening.

According to the acceleration signal from the acceleration sensor 8 installed on the drilling platform and the pressure signal of the compound compensation hydraulic cylinder 2, the control unit 31 sends instructions to the frequency conversion motor 11 and the compensation control valve 13 to control the flow to the inner cylinder of the compound compensation hydraulic cylinder 2. Rod chamber or outer cylinder has rod chamber hydraulic oil flow.

The invention overcomes the disadvantages of slow compensation response speed of traditional passive heave compensation system and poor compensation effect due to pressure fluctuation and friction of the accumulator. Since the hydraulic pump only supplies oil to the rodless chamber of the inner cylinder with a small bore, its power is only used to overcome the frictional resistance and system inertia, so the energy consumption is effectively controlled, the operating cost of the system is reduced, and the compensation accuracy is improved. The utility model has the advantages of simple structure, low energy consumption and good effect. In addition, the composite compensating hydraulic cylinder body of the present invention is installed on the derrick, has no relative movement with the drilling device, and rigid pipelines can be used. Reduces potential for hydraulic line damage compared to flexible tubing required for traveling block compensation.

Claims (2)

1. A heave compensation device for a drill string on an offshore floating drilling platform, including a traveling block (1), a composite compensation hydraulic cylinder (2), a derrick (3), a rocker arm (4), a crown block (5), and a pulley (6) and crown rail (7), dead rope, fast rope, acceleration sensor (8), fuel tank (9), hydraulic pump (10), variable frequency motor (11), hydraulic pump outlet check valve (12), Compensation control valve (13), outer cylinder rod chamber pressure sensor (14), inner cylinder rodless chamber pressure sensor (15), bypass valve (16), speed limiting valve (17), hydraulic shut-off valve (18) , power failure protection valve (19), gas-liquid converter (20), first gate valve (21), second gate valve (23), third gate valve (25), deflation gate valve (26), fifth gate valve (27 ), working gas cylinder (22), air pressure source (24), high-pressure gas cylinder (28), oil supplement check valve (29), safety control valve (30) and control unit (31), composite compensation hydraulic cylinder ( 2) The cylinder body is connected with the derrick (3), the piston rod of the composite compensation hydraulic cylinder (2) is connected with the crown block (5), and supports the movement of the crown block along the guide rail (7) of the crown block, the rocker arm (4) and the The derrick (3) is connected to the crown block (5), and the pressure sensor (14) is installed in the rod chamber of the outer cylinder of the composite compensation hydraulic cylinder (2), and the pressure sensor (14) is installed in the rodless chamber of the inner cylinder of the composite compensation hydraulic cylinder (2). The pressure sensor (15) is fixedly connected to the acceleration sensor (8) on the platform; it is characterized in that the inlet of the hydraulic pump (10) is connected to the oil tank (9), and the outlet of the hydraulic pump (10) is connected to the The P port of the compensation control valve (13) is connected, the T port of the compensation control valve (13) is connected with the fuel tank (9), and the B port of the compensation control valve (13) is connected to the inner cylinder of the two composite compensation hydraulic cylinders (2). The rod cavity is connected, and the A port of the compensation control valve (13) is connected with the rod cavity of the outer cylinder of the two compound compensation hydraulic cylinders (2); one end of the bypass valve (16) is connected with the two compound compensation hydraulic cylinders (2). The rodless chamber of the inner cylinder is connected, and the other end is connected with the rod chamber of the outer cylinder of the two composite compensation hydraulic cylinders (2); the A port of the speed limiting valve (17) is connected with the outer cylinder of the two composite compensation hydraulic cylinders (2). The port B is connected to the A port of the compensation control valve (13); the A port of the hydraulic shut-off valve (18) is connected to the rodless chamber of the outer cylinder of the two composite compensation hydraulic cylinders (2), and the P port is connected to the failure control valve (13). The A port of the electric protection valve (19) is connected; the P port of the power failure protection valve (19) is simultaneously connected with the outlet of the gas-liquid converter (20), the oil supply check valve (29) and the inlet of the safety control valve (30) The other end of the gas-liquid converter (20) is connected with the working gas cylinder (22) through the first gate valve (21) and the second gate valve (23); the working gas cylinder (22) is connected with the deflation gate valve (26), And link to each other with high-pressure gas cylinder (28) by the 5th gate valve (27); High-pressure gas cylinder (28) links to each other with air pressure source (24) by the 3rd gate valve (25); The outlets of the control valve (30) are connected together and connected with the oil tank (9); the control unit (31) is connected with the compensation control Control valve (13), bypass valve (16), power failure protection valve (19), control signal interface of frequency conversion motor (11) are electrically connected, and are connected with outer cylinder rod cavity pressure sensor (14), inner cylinder rodless Chamber pressure sensor (15) and the electric signal connection of the acceleration sensor (8) that is connected on the platform. 2. The heave compensation device for the drill string of the offshore floating drilling platform according to claim 1, characterized in that the composite compensation hydraulic cylinder (2) adopts a composite structure, and the gas-liquid converter (20) passes through the rodless cavity of the outer cylinder Bearing the static load on the crown block (5), the hydraulic pump (10) communicates with the rodless chamber of the inner cylinder or the rod chamber of the outer cylinder through the compensation control valve (13) to overcome the dynamic load during the motion compensation process.

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