Semi-active drill string heave compensation device for ocean floating platform

Abstract

The utility model discloses a semi-active drill column heave compensation device for an ocean floating platform. The semi-active drill column heave compensation device comprises a traveling block, an upper support, a first hydraulic cylinder, a second hydraulic cylinder, a third hydraulic cylinder, a lower support and a large hook. The first hydraulic cylinder and the second hydraulic cylinder are responsible for achieving passive compensation of the heaving motion of the drill column, the third hydraulic cylinder is responsible for achieving active compensation of the heaving motion of the drill column, the passive compensation and the active compensation are combined to form semi-active compensation, the compensation precision is greatly improved, and the bit pressure of a drill bit at the well bottom can be kept basically unchanged. The third hydraulic cylinder adopts a hydraulic transmission form to realize active compensation of the heaving motion of the drill column, and compared with mechanical transmission, the power density is higher, and the size and the weight are smaller under the condition of outputting the same power.

Description

Technical Field

[0001] This utility model relates to the field of oil drilling equipment technology, and in particular to a semi-active drill string heave compensation device for offshore floating platforms. Background Technology

[0002] During offshore oil drilling operations, floating platforms experience not only swaying back and forth and side to side under the influence of waves, but also periodic heave. This periodic heave causes the drill string to move with the floating platform, resulting in changes in the pressure on the drill bit and the bottom of the well, reducing drilling efficiency, increasing costs, and hindering the smooth progress of drilling operations. In severe weather conditions, it can even lead to drilling failure and forced shutdowns. Therefore, to minimize downtime and reduce drilling costs, floating drilling platforms must implement appropriate compensation measures for the heave of the drill string.

[0003] Offshore floating drilling platform heave compensation systems can be categorized into passive, active, and semi-active types based on their power supply method. Passive heave compensation systems are simple in structure and require no additional energy input, but they have a slow response, poor compensation effect, low accuracy, and a large accumulator cylinder. Active heave compensation systems offer good compensation effect, strong anti-interference capability, high compensation accuracy, and stable performance, but they consume a large amount of energy during the compensation process. Semi-active heave compensation systems combine the advantages of both active and passive systems. Compared to passive systems, they can reduce the size of the accumulator cylinder and improve compensation accuracy; compared to active systems, they significantly reduce energy consumption.

[0004] Compared to passive and active heave compensation systems, semi-active heave compensation systems are more widely used. Chinese Patent Application No. 201620327892.0 discloses a rack and pinion drill string heave compensation device, which belongs to the semi-active heave compensation system. Its active compensation for drill string heave motion is achieved using a rack and pinion mechanism. However, rack and pinion mechanisms are mechanical transmissions, and compared to hydraulic transmissions, their power density is lower, resulting in larger size and weight for the same power output. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a semi-active drill string heave compensation device for offshore floating platforms.

[0006] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: A semi-active drill string heave compensation device for an offshore floating platform, comprising a traveling block, the bottom of which is fixedly connected to the top of an upper support; symmetrically mounted cylinder bodies of a first hydraulic cylinder and a second hydraulic cylinder on both sides of the bottom of the upper support; and a cylinder body of a third hydraulic cylinder mounted in the middle of the bottom of the upper support; the piston rods of the first, second, and third hydraulic cylinders are all fixedly connected to the top of a lower support; the bottom of the lower support is fixedly connected to a hook; the inlet of a hydraulic pump is connected to an oil tank; the outlet of the hydraulic pump is connected to the P port of a three-position four-way valve via a check valve; and the A port of the three-position four-way valve is connected to the third hydraulic cylinder. The rodless chamber of the first hydraulic cylinder is connected to the rodless chamber of the second hydraulic cylinder, and the rod-side of the third hydraulic cylinder is connected to the rod-side of the third hydraulic cylinder. The T-side of the first hydraulic cylinder is connected to the oil tank. One end of the first solenoid valve is connected to the rodless chamber of the third hydraulic cylinder, and the other end is connected to the rod-side of the third hydraulic cylinder. One end of the isolation valve is connected to both the rod-side of the first hydraulic cylinder and the rod-side of the second hydraulic cylinder, and the other end is connected to the oil side of the piston accumulator. The gas side of the piston accumulator is connected to the gas cylinder. One end of the second solenoid valve is connected to the P-side of the third hydraulic cylinder, and the other end is connected to the oil side of the piston accumulator. The inlet of the overflow valve is connected to the P-side of the third hydraulic cylinder, and the outlet is connected to the oil tank.

[0007] Preferably, the first hydraulic cylinder and the second hydraulic cylinder have the same structural dimensions.

[0008] Compared with the prior art, the beneficial effects of this utility model are:

[0009] (1) The first and second hydraulic cylinders are responsible for the passive compensation of the drill string's heave motion, while the third hydraulic cylinder is responsible for the active compensation of the drill string's heave motion. The combination of passive and active compensation forms a semi-active compensation, which greatly improves the accuracy of the compensation and can maintain the drill bit's drilling pressure at the bottom of the well.

[0010] (2) The third hydraulic cylinder adopts hydraulic transmission to realize active compensation of the drill string lifting and sinking motion. Compared with mechanical transmission, it has a higher power density and smaller volume and weight under the condition of outputting the same power. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of this utility model;

[0012] Figure 2 This is a schematic diagram of the hydraulic system of this utility model.

[0013] In the diagram: 1. Traveling trolley; 2. Upper support; 3. First hydraulic cylinder; 4. Second hydraulic cylinder; 5. Third hydraulic cylinder; 6. Lower support; 7. Large hook; 8. Hydraulic pump; 9. Oil tank; 10. Check valve; 11. Three-position four-way valve; 12. First solenoid valve; 13. Isolation valve; 14. Piston accumulator; 15. Gas cylinder; 16. Second solenoid valve; 17. Relief valve. Detailed Implementation

[0014] The preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0015] See Figure 1 and Figure 2 A semi-active drill string heave compensation device for offshore floating platforms includes a traveling block 1. The bottom of the traveling block 1 is fixedly connected to the top of an upper support 2. The cylinder bodies of a first hydraulic cylinder 3 and a second hydraulic cylinder 4 are symmetrically mounted on both sides of the bottom of the upper support 2. The cylinder body of a third hydraulic cylinder 5 is mounted in the middle of the bottom of the upper support 2. The piston rods of the first hydraulic cylinder 3, the second hydraulic cylinder 4, and the third hydraulic cylinder 5 are all fixedly connected to the top of a lower support 6. The bottom of the lower support 6 is fixedly connected to a hook 7. The inlet of a hydraulic pump 8 is connected to an oil tank 9. The outlet of the hydraulic pump 8 is connected to the P port of a three-position four-way valve 11 via a check valve 10. The A port of the three-position four-way valve 11 is connected to the rodless chamber of the third hydraulic cylinder 5, the B port of the three-position four-way valve 11 is connected to the rod chamber of the third hydraulic cylinder 5, and the T port of the three-position four-way valve 11 is connected to the oil tank 9. One end of the first solenoid valve 12 is connected to the rodless chamber of the third hydraulic cylinder 5, and the other end is connected to the rod chamber of the third hydraulic cylinder 5. One end of the isolation valve 13 is connected to both the rod chamber of the first hydraulic cylinder 3 and the rod chamber of the second hydraulic cylinder 4, and the other end is connected to the oil side of the piston accumulator 14. The gas side of the piston accumulator 14 is connected to the gas cylinder 15. One end of the second solenoid valve 16 is connected to the P port of the three-position four-way valve 11, and the other end is connected to the oil side of the piston accumulator 14. The inlet of the relief valve 17 is connected to the P port of the three-position four-way valve 11, and the outlet is connected to the oil tank 9.

[0016] In this embodiment, the first hydraulic cylinder 3 and the second hydraulic cylinder 4 have the same structural dimensions.

[0017] This utility model is a semi-active drill string heave compensation device, comprising two parts: passive compensation for drill string heave motion and active compensation for drill string heave motion. The first hydraulic cylinder 3 and the second hydraulic cylinder 4 achieve passive compensation for drill string heave motion, while the third hydraulic cylinder 5 achieves active compensation for drill string heave motion.

[0018] The passive compensation process for the drill string heave is as follows: When the offshore floating platform rises with the waves, the traveling block 1 and the upper support 2, which is fixed to it, move upwards with the platform. The cylinders of the first hydraulic cylinder 3 and the second hydraulic cylinder 4, which are fixed to the upper support 2, also rise accordingly. This process is equivalent to the piston rods of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 extending. Oil from the rod chambers of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 is pumped into the piston accumulator 14, increasing the pressure in the gas cylinder 15. This increases the oil pressure in the piston accumulator 14 and the rod chambers of the first hydraulic cylinder 3 and the second hydraulic cylinder 4. The force of the high-pressure oil acting on the pistons of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 increases, thereby increasing the upward force acting on the lower support 6. This reduces the drilling pressure at the bottom of the well. When the offshore floating platform descends with the waves, the traveling block 1 and the upper support 2, which are fixed to it, move downwards with the platform. The cylinders of the first hydraulic cylinder 3 and the second hydraulic cylinder 4, which are fixed to the upper support 2, also sink accordingly. This process is equivalent to the piston rods of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 retracting. The oil in the piston accumulator 14 is forced into the rod chambers of the first hydraulic cylinder 3 and the second hydraulic cylinder 4. The pressure in the gas cylinder 15 decreases, and the oil pressure in the piston accumulator 14 and the rod chambers of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 also decreases. The force of the high-pressure oil acting on the pistons of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 decreases, thereby reducing the upward force acting on the lower support 6. This increases the drilling pressure of the drill bit at the bottom of the well.

[0019] As the above analysis shows, after adding passive compensation for the heave motion of the drill string, the drilling pressure at the bottom of the well still fluctuates with the rise and fall of the waves, but compared with before the addition, the drilling pressure fluctuation is greatly reduced, which can be used for offshore drilling operations with low compensation accuracy requirements.

[0020] When high compensation accuracy is required, both passive and active compensation are activated simultaneously, and the compensation system is in a semi-active compensation state. The working process is as follows: When the offshore floating platform rises with the waves, as analyzed above, the oil pressure in the rod chambers of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 increases, increasing the upward force acting on the lower support 6. At this time, the first solenoid valve 12 is connected to the lower position of the system, the three-position four-way valve 11 is connected to the left position of the system, and the oil output from the hydraulic pump 8 enters the rodless chamber of the third hydraulic cylinder 5, generating a downward force on the piston of the third hydraulic cylinder 5 and the lower support 6. This counteracts the increase in the upward force on the lower support 6 caused by the increased oil pressure in the rod chambers of the first hydraulic cylinder 3 and the second hydraulic cylinder 4, keeping the drilling pressure at the bottom of the well essentially unchanged. When the offshore floating platform descends with the waves, as analyzed above, the oil pressure in the rod chambers of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 decreases, decreasing the upward force acting on the lower support 6. At this time, the first solenoid valve 12 is connected to the system in its lower position, and the three-position four-way valve 11 is connected to the system in its right position. The oil output by the hydraulic pump 8 enters the rod chamber of the third hydraulic cylinder 5, generating an upward force on the piston and lower support 6 of the third hydraulic cylinder 5. This force counteracts the decrease in the upward force of the lower support 6 caused by the decrease in oil pressure in the rod chambers of the first and second hydraulic cylinders 3 and 4, thus keeping the drilling pressure at the bottom of the well essentially constant. Therefore, after adding semi-active compensation for the drill string heave motion, the drilling pressure at the bottom of the well can be maintained essentially constant as the waves rise and fall. Here, the first and second hydraulic cylinders 3 and 4 are responsible for the passive compensation of the drill string heave motion, while the third hydraulic cylinder 5 is responsible for the active compensation. The combination of passive and active compensation forms semi-active compensation, which greatly improves the accuracy of the compensation and can maintain the drilling pressure at the bottom of the well essentially constant. Because the third hydraulic cylinder 5 uses hydraulic transmission to achieve active compensation for the drill string heave motion, compared with mechanical transmission such as gear and rack mechanisms, it has a higher power density and is smaller in size and weight under the condition of outputting the same power.

[0021] When only passive compensation for drill string heave is performed, the first solenoid valve 12 is connected to the upper position of the system; when semi-active compensation for drill string heave is performed, the first solenoid valve 12 is connected to the lower position of the system.

[0022] When the isolation valve 13 is working normally, it is in the normally open state. In case of sudden system failure caused by wire rope breakage, the isolation valve 13 will automatically close to avoid accidents and ensure that the pistons of the first hydraulic cylinder 3 and the second hydraulic cylinder 4 are stopped in their original positions.

[0023] In actual use, the hydraulic system of the entire heave compensation device inevitably leaks. When it is necessary to replenish the oil, the second solenoid valve 16 is connected to the system in the upper position, and the hydraulic pump 8 can replenish the oil to the first hydraulic cylinder 3, the second hydraulic cylinder 4 and the piston accumulator 14. During normal operation, the second solenoid valve 16 is connected to the system in the lower position.

[0024] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A semi-active drill string heave compensation device for offshore floating platforms, characterized in that, The system includes a traveling trolley (1), the bottom of which is fixedly connected to the top of an upper support (2). The cylinder bodies of a first hydraulic cylinder (3) and a second hydraulic cylinder (4) are symmetrically installed on both sides of the bottom of the upper support (2). The cylinder body of a third hydraulic cylinder (5) is installed in the middle of the bottom of the upper support (2). The piston rods of the first hydraulic cylinder (3), the second hydraulic cylinder (4), and the third hydraulic cylinder (5) are all fixedly connected to the top of a lower support (6). The bottom of the lower support (6) is fixedly connected to a large hook (7). The inlet of a hydraulic pump (8) is connected to an oil tank (9). The outlet of the hydraulic pump (8) is connected to the P port of a three-position four-way valve (11) via a check valve (10). The A port of the three-position four-way valve (11) is connected to the rodless chamber of the third hydraulic cylinder (5). The B port of the three-position four-way valve (11) is connected to the rodless chamber of the third hydraulic cylinder (5). The rod chamber of the third hydraulic cylinder (5) is connected, and the T port of the three-position four-way valve (11) is connected to the oil tank (9); one end of the first solenoid valve (12) is connected to the rodless chamber of the third hydraulic cylinder (5), and the other end is connected to the rod chamber of the third hydraulic cylinder (5); one end of the isolation valve (13) is connected to both the rod chamber of the first hydraulic cylinder (3) and the rod chamber of the second hydraulic cylinder (4), and the other end is connected to the oil side of the piston accumulator (14), and the gas side of the piston accumulator (14) is connected to the gas cylinder (15); one end of the second solenoid valve (16) is connected to the P port of the three-position four-way valve (11), and the other end is connected to the oil side of the piston accumulator (14); the inlet of the overflow valve (17) is connected to the P port of the three-position four-way valve (11), and the outlet is connected to the oil tank (9).

2. The semi-active drill string heave compensation device for offshore floating platforms according to claim 1, characterized in that, The first hydraulic cylinder (3) and the second hydraulic cylinder (4) have the same structural dimensions.

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