A pressure-controlled compensating exhaust system

Abstract

The present invention relates to the field of oil and gas exploration and development tools, and discloses a pressure-controlled compensating exhaust system, including a lifting mechanism, a differential mechanism and a transmission mechanism. The lifting mechanism includes a lifting joint and a sleeve assembly, and the differential mechanism includes a differential pressure rod and a differential connecting sleeve that can move relatively. The transmission mechanism is connected to the differential connecting sleeve, including a diverter gas injection joint, a piston pressure joint and a negative pressure exhaust joint that are connected in sequence. The piston pressure joint has a accommodating chamber, and a piston assembly is arranged in the accommodating chamber. The piston assembly can move in the accommodating chamber and divide the accommodating chamber into a high-pressure gas chamber and a pressure-conducting chamber. The high-pressure gas chamber can be injected with inert gas, and the pressure-conducting chamber can be injected with drilling fluid. An exhaust hole is arranged on the negative pressure exhaust joint, and the negative pressure exhaust joint can be driven by the differential connecting sleeve and move relative to the sleeve assembly, so that the sleeve assembly closes the exhaust hole, and then the transmission mechanism is used to supplement the pressure of the coring inner cylinder connected to the negative pressure exhaust joint.

Description

Technical Field

[0001] The invention relates to the field of oil and natural gas exploration and development tools, and in particular to a pressure-controlled compensating exhaust system. Background Art

[0002] After the existing pressure-maintaining and sealed coring tools are used on site, there are phenomena of low pressure-maintaining rate and destruction of fracture structure after core testing. This is mainly because the air in the coring inner tube cannot be removed, resulting in a decrease in the temperature and pressure of the coring inner tube during the drilling process. The existing pressure-maintaining and sealed coring tools with pressure compensation cannot stably and accurately compensate the pressure of the coring inner tube, and excessive or insufficient pressure compensation will also destroy the original physical properties of the core. Specifically, the existing pressure control and compensation device transmits pressure to the coring inner tube directly or indirectly through a connecting sleeve. The gas pressure value injected into the pressure chamber is set only by calculating the static liquid column pressure value as a standard, and the pressure is fixed without subsequent supplementary function. It is generally greater than the bottom hole pressure value, or a maximum limit pressure value within a safe range is set. It is impossible to scientifically compensate the pressure to cope with the complex changes in formation pressure and the changes in temperature and pressure during the drilling process. In addition, since there is a certain amount of air in the coring inner barrel and the gas compression ratio is large, the pressure compensation of the coring inner barrel is directly performed by gas. Factors such as the core length in the coring inner barrel and the gas-liquid mixing ratio will cause the pressure compensation effect to be unstable, which may easily cause the pressure compensation to be too large or too low, and the physical properties of the core under the original formation pressure state cannot be maintained. If the current bottom hole pressure is high, the pressure value of the injected gas will also increase, and the opening force of the push sleeve will be very large. The requirements for the material strength of the connecting sleeve and the pushing part are very strict, and there is a possibility of failure in pushing the connecting sleeve.

[0003] Therefore, there is an urgent need for a pressure-controlled compensating exhaust system to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a pressure-controlled compensating exhaust system, which can not only automatically and accurately compensate the pressure of the coring inner barrel according to the current well depth pressure using liquid, but also exhaust the air in the coring inner barrel, further protecting the physical properties of the core under the original bottom stress.

[0005] As conceived above, the technical solution adopted by the present invention is:

[0006] A pressure-controlled compensating exhaust system, comprising:

[0007] A lifting mechanism, the lifting mechanism comprising a lifting joint and a sleeve assembly, the sleeve assembly comprising a linkage push cylinder, one end of the lifting joint is passed through the linkage push cylinder, and the positions of the lifting joint and the linkage push cylinder are relatively fixed;

[0008] A differential mechanism is arranged in the linkage push cylinder, the differential mechanism comprises a differential pressure rod and a differential connecting sleeve which are connected to each other, the differential pressure rod is connected to the lifting joint, the positions of the differential pressure rod and the lifting joint are relatively fixed, and the differential connecting sleeve can move relative to the differential pressure rod;

[0009] A transmission mechanism is arranged in the linkage push cylinder and connected to the differential connection sleeve. The transmission mechanism includes a split flow gas injection joint, a piston pressure joint and a negative pressure exhaust joint which are connected in sequence. The piston pressure joint has a receiving chamber. A piston assembly is arranged in the receiving chamber. The piston assembly can move in the receiving chamber and divide the receiving chamber into a high-pressure gas chamber and a pressure-conducting chamber. The high-pressure gas chamber can be injected with inert gas, and the pressure-conducting chamber can be injected with drilling fluid.

[0010] An exhaust hole is provided on the negative pressure exhaust joint, and the negative pressure exhaust joint can be driven by the differential connecting sleeve and move relative to the sleeve assembly so that the sleeve assembly can open or close the exhaust hole. One end of the negative pressure exhaust joint is connected to the pressure guiding chamber through the main negative pressure valve, and the other end is connected to the coring inner cylinder. When the exhaust hole is closed and the pressure of the coring inner cylinder is lower than the pressure in the high-pressure gas chamber, the transmission mechanism can replenish the pressure for the coring inner cylinder.

[0011] As a preferred solution of the pressure-controlled compensating exhaust system, one end of the differential pressurizing rod is sealed and connected to the lifting joint, and the other end of the differential pressurizing rod has a sealing portion. The differential connecting sleeve and the diverter gas injection joint are connected and surrounded to form a cavity. The sealing portion is located in the cavity and divides the cavity into a differential cavity and a diverter cavity. The sealing portion is sealed and abutted against the inner wall of the cavity, and the differential connecting sleeve can move relative to the sealing portion to change the size of the differential cavity and the diverter cavity.

[0012] As a preferred solution of the pressure-controlled compensating exhaust system, the differential pressurizing rod is provided with a through first hole along its axial direction, and the differential pressurizing rod is provided with a through second hole along its radial direction, the second hole is connected to the first hole, the first hole and the second hole are jointly used to connect the lifting joint and the differential chamber, and the first hole is used to connect the lifting joint and the diverter chamber.

[0013] As a preferred solution of the pressure-controlled compensating exhaust system, a differential hole is circumferentially arranged on the differential connecting sleeve, and the drilling fluid entering the differential cavity through the second hole can flow out of the transmission mechanism through the differential hole.

[0014] As a preferred solution of the pressure-controlled compensating exhaust system, the diverter holes are circumferentially arranged on the diverter gas injection joint, and the drilling fluid entering the diverter cavity through the first hole can flow out of the transmission mechanism through the diverter holes.

[0015] As a preferred solution of the pressure-controlled compensating exhaust system, the pressure-controlled compensating exhaust system further includes a plugging member, which is used to plug the first hole to block the communication between the lifting joint and the diverter cavity.

[0016] As a preferred solution of the pressure-controlled compensating exhaust system, a side negative pressure valve is arranged circumferentially of the piston pressure joint, and the drilling fluid outside the transmission mechanism can enter the pressure guiding chamber through the side negative pressure valve.

[0017] As a preferred solution of the pressure-controlled compensating exhaust system, the sleeve assembly also includes a sealing sleeve, which is sleeved on the negative pressure exhaust joint. The sealing sleeve can slide relative to the negative pressure exhaust joint by abutting against the linkage push cylinder to close the exhaust hole.

[0018] As a preferred solution of the pressure-controlled compensated exhaust system, the piston assembly includes a piston, a spring and a spring seat, the spring seat is arranged in the pressure-conducting chamber, one end of the spring is sleeved on the spring seat, and the other end of the spring is sleeved on the piston, and the spring can be used to adjust the relative position of the piston and the spring seat to balance the pressure of the high-pressure gas chamber and the pressure-conducting chamber.

[0019] As a preferred solution of the pressure-controlled compensating exhaust system, an injection valve is arranged circumferentially of the diverter gas injection joint, and an injection channel connecting the injection valve and the high-pressure gas storage is also arranged on the diverter gas injection joint. The injection valve and the injection channel are used to inject inert gas into the high-pressure gas storage.

[0020] The beneficial effects of the present invention are:

[0021] The pressure-controlled compensating exhaust system proposed in the present invention includes a lifting mechanism, a differential mechanism and a transmission mechanism. The lifting mechanism includes a lifting joint and a sleeve assembly, and the sleeve assembly includes a linkage push cylinder. One end of the lifting joint is inserted into the linkage push cylinder, and the positions of the lifting joint and the linkage push cylinder are relatively fixed. The differential mechanism and the transmission mechanism are both arranged in the linkage push cylinder. The differential mechanism includes a differential pressure rod and a differential connecting sleeve. The differential pressure rod is connected to the lifting joint, and the differential connecting sleeve is connected to the differential pressure rod and can move relative to the differential pressure rod. The transmission mechanism includes a shunt gas injection joint, a piston pressure joint and a negative pressure exhaust joint connected in sequence, and the shunt gas injection joint is connected to the differential connecting sleeve. That is, the positions of the lifting joint, the linkage push cylinder and the differential pressure rod are relatively fixed, while the positions of the differential connecting sleeve and the transmission mechanism are relatively fixed.

[0022] The piston pressure joint has a accommodating chamber, and a piston assembly is arranged in the accommodating chamber. The piston assembly can separate the accommodating chamber into a high-pressure gas chamber and a pressure-conducting chamber. The high-pressure gas chamber can be injected with inert gas, and the pressure-conducting chamber can be injected with drilling fluid. During the process of going down the well or pulling out of the well, as the pressure continues to change, the piston assembly can move in the accommodating chamber to compress the drilling fluid in the pressure-conducting chamber or the inert gas in the high-pressure gas chamber. Specifically, the pressure-conducting chamber is connected to one end of the negative pressure exhaust joint through the main negative pressure valve, and the other end of the negative pressure exhaust joint is connected to the coring inner cylinder, that is, the pressure of the negative pressure exhaust joint and the coring inner cylinder will be consistent. During the process of pulling out of the well, when the pressure of the coring inner cylinder is reduced due to the influence of temperature, the piston assembly will move in the direction close to the pressure-conducting chamber, and the drilling fluid in the pressure-conducting chamber will be compressed to the coring inner cylinder through the main negative pressure valve, so as to conduct pressure and increase the pressure of the coring inner cylinder. Moreover, there is no gas in the pressure-conducting chamber and the core sampling inner tube at this time. The piston assembly is used to compress the liquid for pressure control compensation. Because the liquid compression ratio is small, the pressure control compensation effect can be as close to the bottom hole pressure as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a structural schematic diagram of a pressure-controlled compensating exhaust system provided in an embodiment of the present invention (first use state);

[0024] Figure 2 is a structural schematic diagram of a pressure-controlled compensating exhaust system provided in an embodiment of the present invention (second use state);

[0025] Figure 3 is a schematic structural diagram of a differential connection sleeve provided in an embodiment of the present invention;

[0026] Figure 4 It is a schematic structural diagram of a linkage push cylinder provided in an embodiment of the present invention.

[0027] In the figure:

[0028] 1. Lift the joint;

[0029] 2. Sleeve assembly; 21. Linkage push cylinder; 22. Sealing sleeve;

[0030] 3. differential pressure rod; 31. sealing portion; 32. first hole; 33. second hole;

[0031] 4. Differential connection sleeve; 41. Differential hole;

[0032] 5. Diverter gas injection joint; 51. Diverter hole; 52. Gas injection valve; 53. Gas injection channel;

[0033] 6. Piston pressure joint; 61. Side negative pressure valve;

[0034] 7. Negative pressure exhaust connector; 71. Main negative pressure valve; 72. Exhaust hole;

[0035] 8. Piston assembly; 81. Piston; 82. Spring; 83. Spring seat;

[0036] 9. Sealing parts;

[0037] 10. Differential chamber; 20. Diverter chamber; 30. High-pressure gas chamber; 40. Pressure-guiding chamber; 50. Exhaust chamber. DETAILED DESCRIPTION

[0038] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and through specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, not all.

[0039] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0041] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0042] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0043] In order to avoid the pressure change of the core caused by the temperature during the drilling process, and to avoid the influence of the overburden pressure, net overburden pressure and pore pressure on the accurate measurement of the core permeability, the core can maintain a stable overburden pressure and pore pressure balance under the bottom hole pressure state, so as to improve the accuracy and precision of the core measurement. This embodiment provides a pressure control compensation exhaust system, which can not only use liquid to automatically implement accurate pressure compensation for the coring inner barrel according to the current well depth pressure, so that the pressure of the coring inner barrel is always close to the bottom hole pressure, but also can empty the air in the coring inner barrel, reduce the pressure loss caused by the high compression ratio gas, and further protect the physical properties of the core under the original bottom layer stress.

[0044] like Figures 1 to 4 As shown, the pressure-controlled compensation exhaust system includes a lifting mechanism, a differential mechanism and a transmission mechanism. The lifting mechanism includes a lifting joint 1 and a sleeve assembly 2, and the sleeve assembly 2 includes a linkage push cylinder 21. One end of the lifting joint 1 is inserted into the linkage push cylinder 21, and the positions of the lifting joint 1 and the linkage push cylinder 21 are relatively fixed. The differential mechanism and the transmission mechanism are both arranged in the linkage push cylinder 21. The differential mechanism includes a differential pressurizing rod 3 and a differential connecting sleeve 4. The differential connecting sleeve 4 is connected to the differential pressurizing rod 3, and the differential pressurizing rod 3 is connected to the lifting joint 1. The transmission mechanism includes a shunt gas injection joint 5, a piston pressure joint 6 and a negative pressure exhaust joint 7 connected in sequence, and the shunt gas injection joint 5 is connected to the differential connecting sleeve 4. Optionally, the linkage push cylinder 21 is threadedly connected to the lifting joint 1. Optionally, the shunt gas injection joint 5 is threadedly connected to the differential connecting sleeve 4. Optionally, the differential pressurizing rod 3 is threadedly sealed to the lifting joint 1. Optionally, the shunt gas injection joint 5 is threadedly sealed to the piston pressure joint 6. When the differential connection sleeve 4 moves relative to the differential pressure rod 3, the transmission mechanism connected to the differential connection sleeve 4 can move relative to the differential pressure rod 3, that is, in this embodiment, the positions of the lifting joint 1, the linkage push cylinder 21 and the differential pressure rod 3 are relatively fixed, while the positions of the differential connection sleeve 4 and the transmission mechanism are relatively fixed. How to achieve the movement of the differential connection sleeve 4 relative to the differential pressure rod 3 will be described in detail below.

[0045] The piston pressure joint 6 has a receiving chamber, and a piston assembly 8 is arranged in the receiving chamber. The piston assembly 8 can separate the receiving chamber into a high-pressure gas chamber 30 and a pressure-conducting chamber 40. During the process of going down the well, the high-pressure gas chamber 30 is located above the pressure-conducting chamber 40. The high-pressure gas chamber 30 can be injected with inert gas, and the pressure-conducting chamber 40 can be injected with drilling fluid. The piston assembly 8 can move in the receiving chamber to compress the drilling fluid in the pressure-conducting chamber 40 or the inert gas in the high-pressure gas chamber 30. Specifically, the pressure-conducting chamber 40 is connected to one end of the negative pressure exhaust joint 7 through the main negative pressure valve 71, and the other end of the negative pressure exhaust joint 7 is connected to the coring inner barrel (not shown in the figure), so that the negative pressure exhaust joint 7 can keep the pressure consistent with that of the coring inner barrel. During the process of pulling out of the well, when the pressure of the coring inner barrel is reduced due to the influence of temperature, the piston assembly 8 will move in the direction close to the pressure-conducting chamber 40, and the drilling fluid in the pressure-conducting chamber 40 will be compressed to the coring inner barrel through the main negative pressure valve 71, so as to conduct pressure transmission and increase the pressure of the coring inner barrel. At this time, there is no gas in the pressure-conducting chamber 40 and the coring inner tube, and the piston assembly 8 is used to compress the drilling fluid for pressure control compensation. Because the liquid compression ratio is small, the pressure control compensation effect can be as close to the bottom hole pressure as possible.

[0046] In this embodiment, the negative pressure exhaust connector 7 has an exhaust chamber 50, and the core inner tube is arranged in the negative pressure exhaust connector 7 and communicates with the exhaust chamber 50, that is, the exhaust chamber 50 and the core inner tube have the same pressure. As mentioned above, when the pressure of the core inner tube gradually decreases, that is, when the pressure of the exhaust chamber 50 is less than the pressure of the high-pressure gas chamber 30, the piston assembly 8 will move in the accommodating chamber to the side close to the negative pressure exhaust connector 7, so as to conduct pressure through the main negative pressure valve 71 in the pressure guide chamber 40 to supplement the pressure of the core inner tube.

[0047] Optionally, the gas in the exhaust chamber 50 and the coring inner barrel is discharged through the exhaust hole 72 provided on the negative pressure exhaust joint 7. This is because only by exhausting the air in the coring inner barrel during the coring process and reducing the factors of large volume changes affected by temperature changes can the core in the coring inner barrel be completely wrapped by drilling fluid, laying the foundation for precise pressure control compensation in the later stage. In the subsequent drilling process, the exhaust hole 72 needs to be blocked again to maintain pressure. In this embodiment, the opening or closing of the exhaust hole 72 is realized by the sleeve assembly 2.

[0048] Specifically, the sleeve assembly 2 further includes a sealing sleeve 22, which is sleeved on the negative pressure exhaust joint 7. Before the coring operation begins, the exhaust hole 72 is in an open state, that is, the sealing sleeve 22 should be arranged to avoid the exhaust hole 72, and the exhaust hole 72 needs to be closed only during the drilling process. Figure 1 and Figure 2As shown, the exhaust hole 72 is arranged in the circumference of the negative pressure exhaust joint 7, and the negative pressure exhaust joint 7 is connected to the differential connecting sleeve 4. When the differential connecting sleeve 4 moves relative to the differential pressurizing rod 3, the negative pressure exhaust joint 7 will be driven to move upward, and the negative pressure exhaust joint 7 will drive the sealing sleeve 22 mounted thereon to move upward at the same time until the sealing sleeve 22 abuts against the linkage push cylinder 21. At this time, the movement of the sealing sleeve 22 is restricted. At this time, the negative pressure exhaust joint 7 continues to move upward, and the positions of the negative pressure exhaust joint 7 and the sealing sleeve 22 will change, thereby realizing the blocking of the exhaust hole 72, and the exhaust hole 72 is closed.

[0049] like Figure 1 and Figure 2 As shown, one end of the differential pressurizing rod 3 is connected to the lifting joint 1, and the other end is connected to the differential connecting sleeve 4. The end of the differential connecting sleeve 4 that is not connected to the differential pressurizing rod 3 is connected to the shunt gas injection joint 5 and surrounded to form a cavity. Further, the other end of the differential pressurizing rod 3 has a sealing portion 31, which extends into the cavity and divides the cavity into a differential cavity 10 and a shunt cavity 20, and the sealing portion 31 can move in the cavity, that is, the size of the differential cavity 10 and the shunt cavity 20 can be changed. Optionally, a through hole is provided on the differential connecting sleeve 4. During assembly, one end of the differential pressurizing rod 3 extends out of the cavity through the through hole and the sealing portion 31 is clamped in the cavity. The differential pressurizing rod 3 is sealed and connected to the differential connecting sleeve 4, and a sealing ring is sandwiched between the sealing portion 31 and the inner wall of the cavity. Optionally, a sealing ring is also sandwiched between the hole wall of the through hole and the differential pressurizing rod 3. Optionally, a sealing ring is also sandwiched between the differential pressure rod 3 and the lifting joint 1 .

[0050] Furthermore, the differential pressure rod 3 is provided with a through first hole 32 along its axial direction, and a through second hole 33 along its radial direction, and the second hole 33 is connected to the first hole 32, and the lifting joint 1 can be connected to the differential chamber 10 through the first hole 32 and the second hole 33, and can also be connected to the diverter chamber 20 only through the first hole 32. The sealed connection between the aforementioned parts is to ensure that the diverter chamber 20 and the differential chamber 10 are not connected, so that the drilling fluid can enter the diverter chamber 20 or the differential chamber 10 from the lifting joint 1 according to the preset channel. Figure 1 and Figure 2As shown, the first hole 32 is through along the axial direction of the differential pressure rod 3, and this direction is also the downhole direction of the coring tool. In the case that both the first hole 32 and the second hole 33 are connected, the drilling fluid will preferentially enter the diversion chamber 20 through the first hole 32. Preferably, the diameter of the first hole 32 is much larger than the diameter of the second hole 33. However, if the connection between the first hole 32 and the diversion chamber 20 is blocked, the drilling fluid can only enter the differential chamber 10, and as the drilling fluid in the differential chamber 10 increases, the pressure in the differential chamber 10 increases, which will drive the differential connection sleeve 4 to move relative to the differential pressure rod 3. It can be seen that when the drilling fluid in the differential chamber 10 continues to increase, the differential connection sleeve 4 will move to one side of the lifting joint 1 to increase the volume of the differential chamber 10, that is, all components of the transmission mechanism will move to one side of the lifting joint 1, so that the exhaust hole 72 set on the negative pressure exhaust joint 7 can be blocked by the sealing sleeve 22. Optionally, a plurality of second holes 33 are provided, and the plurality of second holes 33 are distributed at intervals along the circumference of the differential pressurizing rod 3 to ensure the liquid inlet speed of the differential chamber 10 .

[0051] Optionally, the pressure-controlled compensating exhaust system further includes a plugging member 9, which is used to block the connection between the first hole 32 and the diverter chamber 20. In this embodiment, the plugging member 9 is a steel ball, and the diameter of the steel ball is adapted to the diameter of the first hole 32. After coring is completed, the steel ball is dropped into the first hole 32 so that the drilling fluid cannot enter the diverter chamber 20 through the first hole 32, but continuously enters the differential chamber 10, so as to complete the movement of the transmission mechanism relative to the linkage push cylinder 21. After the plugging member 9 is dropped into the first hole 32, it should avoid obstructing the connection between the second hole 33 and the differential chamber 10, that is, in the axial direction of the differential pressure rod 3, there should be at least one gap of the plugging member 9 between the first hole 32 and the second hole 33.

[0052] Furthermore, the liquid inlet of the differential chamber 10 should maintain a dynamic balance, and the volume of the differential chamber 10 has a maximum value, such as Figure 3 As shown, the differential connection sleeve 4 is provided with differential holes 41 in the circumferential direction. As the differential connection sleeve 4 continuously moves toward one side of the lifting joint 1, the differential holes 41 will gradually approach the differential pressure rod 3 until communicating with the second hole 33. Optionally, the number and position of the differential holes 41 correspond to the number and position of the second holes 33, that is, when the differential connection sleeve 4 moves along the axial direction of the differential connection rod, each differential hole 41 can overlap with the corresponding second hole 33. At this time, the drilling fluid flowing into the differential cavity 10 through the second hole 33 will flow out of the transmission mechanism from the differential hole 41.

[0053] Similarly, the circumference of the diverter gas injection joint 5 is also provided with a diverter hole 51. After the drilling fluid enters the diverter cavity 20 through the first hole 32, it will flow out of the transmission mechanism from the diverter hole 51. Optionally, a plurality of diverter holes 51 are provided. The main purpose of the circulation of the drilling fluid is to close the exhaust hole 72 during the drilling process, that is, after the steel ball is put in, and keep the exhaust hole 72 open when the steel ball is not put in.

[0054] However, the drilling fluid enters the pressure-conducting chamber 40 according to the change of the bottom hole pressure. Optionally, a side negative pressure valve 61 is provided around the piston pressure joint 6. When the pressure in the pressure-conducting chamber 40 is lower than the bottom hole pressure, the drilling fluid between the transmission mechanism and the inner wall of the linkage push cylinder 21 can enter the pressure-conducting chamber 40 through the side negative pressure valve 61, so that the pressure difference between the pressure-conducting chamber 40 and the high-pressure gas chamber 30 is within a preset difference range. Optionally, as Figure 4 As shown, a hole is provided on the side wall of the linkage push cylinder 21. During the process of going down into the well, the drilling fluid can enter the linkage push cylinder 21, so that the drilling fluid can flow relatively quickly inside the transmission mechanism.

[0055] The reason why there is a pressure difference between the pressure-conducting chamber 40 and the high-pressure gas chamber 30 is because of the piston assembly 8 disposed in the accommodating chamber. Figure 3 As shown, in this embodiment, the piston assembly 8 includes a piston 81, a spring 82 and a spring seat 83, the spring seat 83 is arranged in the pressure-conducting chamber 40, one end of the spring 82 is sleeved on the spring seat 83, and the other end of the spring 82 is sleeved on the piston 81, the spring seat 83 and the inner wall of the pressure-conducting chamber 40 are relatively fixed, and the piston 81 can move in the pressure-conducting chamber 40 to balance the pressure of the high-pressure gas chamber 30 and the pressure-conducting chamber 40. Specifically, as can be seen from the above, the pressure-conducting chamber 40 can inject drilling fluid through the side negative pressure valve 61 to maintain a pressure that is relatively consistent with the bottom of the well, so when the bottom hole pressure is higher than the pressure in the high-pressure gas chamber 30, the piston 81 will move to the side close to the split gas injection joint 5 until the pressure in the high-pressure gas chamber 30 is balanced with the pressure in the pressure-conducting chamber 40, but because the piston 81 is driven by the spring 82 to exert a certain force on the high-pressure gas pressure, the pressure in the high-pressure gas chamber 30 will be slightly greater than the current bottom hole pressure.

[0056] In addition, because the bottom hole pressure is much greater than the atmospheric pressure, in order to make the pressure guide chamber 40 always have a pressure value that is relatively consistent with the bottom hole pressure during the drilling process, before the coring work begins, an inert gas slightly smaller than the static liquid column pressure value of the current well depth should be injected into the high-pressure gas chamber 30 to push the piston 81 to the bottom of the accommodating chamber, that is, compress the spring 82 to make the piston 81 close to the spring seat 83. In the process of going down to the bottom of the well, as the pressure continues to increase, the drilling fluid will continue to enter the pressure guide chamber 40 to move the piston 81 upward. When the coring is completed, the pressure of the pressure guide chamber 40, the coring inner cylinder and the bottom hole is consistent. At this time, the steel ball is put in, the differential connection sleeve 4 moves upward, and the exhaust hole 72 is closed. In the process of drilling, the pressure of the coring inner cylinder is reduced due to the influence of temperature, and the high-pressure gas chamber 30 pushes the piston 81 downward again until the pressure in the high-pressure gas chamber 30 is balanced with the pressure in the pressure guide chamber 40. That is, at this time, the drilling fluid in the pressure-conducting chamber 40 will be compressed to control the pressure of the coring inner tube so that the pressure of the coring inner tube is consistent with the bottom hole pressure. At this time, the gas in the coring inner tube has been discharged, and the drilling fluid can completely wrap the core in the coring inner tube.

[0057] Optionally, a gas injection valve 52 is provided around the circumference of the split gas injection joint 5, and a gas injection channel 53 connecting the gas injection valve 52 and the high-pressure gas chamber 30 is also provided on the split gas injection joint 5, that is, the staff can use the gas injection valve 52 and the gas injection channel 53 to inject inert gas into the high-pressure gas chamber 30. Optionally, multiple gas injection valves 52 are provided, and multiple gas injection valves 52 can be connected to one gas injection channel 53. In addition, because the transmission mechanism is provided in the linkage push cylinder 21, during assembly, an inert gas slightly smaller than the static liquid column pressure value of the current well depth should be first injected into the high-pressure gas chamber 30 through the gas injection valve 52, and then the linkage push cylinder 21 should be assembled. In this embodiment, nitrogen can be selected as the inert gas.

[0058] In order to discharge the gas in the pressure chamber 40, before the coring work begins, the pressure chamber 40 needs to be filled with water, and then as the drilling fluid enters the pressure chamber 40, the previously injected water will be discharged first, and then the drilling fluid will be compressed and flow. Figure 1 and Figure 2 As shown, the spring seat 83 is a columnar structure, and the spring seat 83 has a certain thickness along its axial direction, and is provided with a through hole along its axial direction. The piston 81 includes a piston body and a convex portion extending toward one side of the spring seat 83, and the convex portion is also provided with a hole to increase the accommodation space of the pressure guide chamber 40.

[0059] The above embodiments are only to illustrate the basic principles and characteristics of the present invention. The present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and modifications, which are within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A pressure-controlled compensating exhaust system, characterized in that: include: A lifting mechanism, the lifting mechanism comprising a lifting joint (1) and a sleeve assembly (2), the sleeve assembly (2) comprising a linkage push cylinder (21), one end of the lifting joint (1) being inserted into the linkage push cylinder (21), and the positions of the lifting joint (1) and the linkage push cylinder (21) being relatively fixed; A differential mechanism is arranged in the linkage push cylinder (21), the differential mechanism comprising a differential pressure rod (3) and a differential connection sleeve (4) which are connected to each other, the differential pressure rod (3) is connected to the lifting joint (1), the positions of the differential pressure rod (3) and the lifting joint (1) are relatively fixed, and the differential connection sleeve (4) can move relative to the differential pressure rod (3); A transmission mechanism is arranged in the linkage push cylinder (21) and connected to the differential connection sleeve (4). The transmission mechanism comprises a flow-dividing gas injection joint (5), a piston pressure joint (6) and a negative pressure exhaust joint (7) which are connected in sequence. The piston pressure joint (6) has a receiving chamber. A piston assembly (8) is arranged in the receiving chamber. The piston assembly (8) can move in the receiving chamber and divide the receiving chamber into a high-pressure gas chamber (30) and a pressure-conducting chamber (40). The high-pressure gas chamber (30) can be injected with inert gas, and the pressure-conducting chamber (40) can be injected with drilling fluid. The negative pressure exhaust connector (7) is provided with an exhaust hole (72). The negative pressure exhaust connector (7) can be driven by the differential connection sleeve (4) and move relative to the sleeve assembly (2) so that the sleeve assembly (2) can open or close the exhaust hole (72). One end of the negative pressure exhaust connector (7) is connected to the pressure guide chamber (40) through the main negative pressure valve (71), and the other end is connected to the coring inner cylinder. When the exhaust hole (72) is closed and the pressure of the coring inner cylinder is lower than the pressure in the high-pressure gas chamber (30), the transmission mechanism can replenish the pressure of the coring inner cylinder.

2. The pressure-controlled compensated exhaust system according to claim 1, characterized in that: One end of the differential pressurizing rod (3) is sealingly connected to the lifting joint (1), and the other end of the differential pressurizing rod (3) has a sealing portion (31). The differential connecting sleeve (4) and the diverter gas injection joint (5) are connected and enclosed to form a cavity. The sealing portion (31) is located in the cavity and divides the cavity into a differential cavity (10) and a diverter cavity (20). The sealing portion (31) is sealingly abutted against the inner wall of the cavity. The differential connecting sleeve (4) can move relative to the sealing portion (31) to change the size of the differential cavity (10) and the diverter cavity (20).

3. The pressure-controlled compensating exhaust system according to claim 2, characterized in that: The differential pressurizing rod (3) is provided with a through first hole (32) along its axial direction, and the differential pressurizing rod (3) is provided with a through second hole (33) along its radial direction, the second hole (33) is connected to the first hole (32), the first hole (32) and the second hole (33) are used together to connect the lifting joint (1) and the differential chamber (10), and the first hole (32) is used to connect the lifting joint (1) and the diverter chamber (20).

4. The pressure-controlled compensated exhaust system according to claim 3, characterized in that: A differential hole (41) is arranged in the circumference of the differential connection sleeve (4), and the drilling fluid that enters the differential cavity (10) through the second hole (33) can flow out of the transmission mechanism through the differential hole (41).

5. The pressure-controlled compensating exhaust system according to claim 3, characterized in that: The diverter hole (51) is arranged around the diverter gas injection joint (5), and the drilling fluid that enters the diverter cavity (20) through the first hole (32) can flow out of the transmission mechanism through the diverter hole (51).

6. The pressure-controlled compensating exhaust system according to claim 3, characterized in that: The pressure-controlled compensating exhaust system further comprises a blocking member (9), wherein the blocking member (9) is used to block the first hole (32) so as to block the communication between the lifting joint (1) and the diverter chamber (20).

7. The pressure-controlled compensating exhaust system according to claim 1, characterized in that: A side negative pressure valve (61) is arranged in the circumference of the piston pressure joint (6), and the drilling fluid outside the transmission mechanism can enter the pressure guide chamber (40) through the side negative pressure valve (61).

8. The pressure-controlled compensating exhaust system according to claim 1, characterized in that: The sleeve assembly (2) further comprises a sealing sleeve (22), wherein the sealing sleeve (22) is sleeved on the negative pressure exhaust joint (7), and the sealing sleeve (22) can slide relative to the negative pressure exhaust joint (7) by abutting against the linkage push cylinder (21) to close the exhaust hole (72).

9. The pressure-controlled compensating exhaust system according to claim 1, characterized in that: The piston assembly (8) comprises a piston (81), a spring (82) and a spring seat (83); the spring seat (83) is arranged in the pressure-conducting chamber (40); one end of the spring (82) is sleeved on the spring seat (83), and the other end of the spring (82) is sleeved on the piston (81); the spring (82) can be used to adjust the relative position of the piston (81) and the spring seat (83) to balance the pressure of the high-pressure gas chamber (30) and the pressure-conducting chamber (40).

10. The pressure-controlled compensated exhaust system according to claim 1, characterized in that: An injection valve (52) is arranged around the circumference of the diverter gas injection joint (5), and an injection channel (53) connecting the injection valve (52) and the high-pressure gas chamber (30) is also arranged on the diverter gas injection joint (5), and the injection valve (52) and the injection channel (53) are used to inject inert gas into the high-pressure gas chamber (30).

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