High-temperature and high-pressure underground pressure maintaining sampler

Abstract

The invention relates to a high-temperature and high-pressure underground pressure maintaining sampler which comprises a trigger slide valve, a low-pressure nitrogen chamber, a top liquid release chamber, a top liquid safety valve, a high-pressure nitrogen chamber, a high-pressure nitrogen release slide valve assembly, a pressure maintaining chamber trigger assembly, a sampling chamber trigger assembly, a sampling chamber, a pressure maintaining piston, a sampling chamber valve element assembly and a lower end. A top liquid circulation loop is arranged between the upper side of the pressure maintaining piston and the top liquid release chamber; the sampling chamber is laterally provided with a sampling inlet communicated with the stratum, the pressure maintaining piston is located in the sampling chamber, the upper side of the pressure maintaining piston is provided with a pressure maintaining chamber used for alternate action of top liquid and high-pressure nitrogen, and the low-pressure nitrogen chamber is filled with low-pressure nitrogen for sealing and blocking connection and disconnection between the top liquid circulation loop and the top liquid release chamber. According to the sampler, jacking liquid is packed through low-pressure nitrogen, the sampling chamber is prevented from being jacked in advance by formation pressure liquid before the sampling chamber descends to a target layer under pressure, and the sampling chamber after sampling is subjected to pressure maintaining through high-pressure nitrogen, so that the pressure of sampling liquid in the process of lifting the ground after sampling is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of downhole mining or geological exploration technology, and in particular to a high-temperature and high-pressure downhole pressure-maintaining sampler for high-pressure formation fluids such as deep wells, ultra-deep wells, and shale gas. Background Technology

[0002] The existing downhole samplers have the following problems: insufficient pressure holding capacity after downhole sampling; after the formation sample reaches the surface, due to the temperature difference, the actual pressure of the sample drops significantly and is lower than the sample dew point pressure. After reheating and pressurizing, the original high-pressure properties of the sample cannot be restored, which limits the sampling to the surface. Summary of the Invention

[0003] This invention addresses the problem in existing downhole samplers that cannot maintain pressure after sampling and temperature drop, by providing a high-temperature, high-pressure downhole pressure-maintaining sampler that can maintain the sampling chamber pressure even after the temperature drops.

[0004] The objective of this invention is achieved by providing a high-temperature, high-pressure downhole pressure-holding sampler, comprising, from top to bottom, a trigger slide valve, a low-pressure nitrogen chamber, a top fluid release chamber, a top fluid safety valve, a high-pressure nitrogen chamber, a high-pressure nitrogen release slide valve assembly, a pressure-holding chamber trigger assembly, a sampling chamber trigger assembly, a sampling chamber, a pressure-holding piston, a sampling chamber valve core assembly, and a lower end. A top fluid flow circuit is provided between the upper side of the pressure-holding piston and the top fluid release chamber. The sampling chamber has a sampling inlet communicating with the formation on its side. The pressure-holding piston is located inside the sampling chamber. A pressure-holding chamber for alternating action of top fluid and high-pressure nitrogen is provided on the upper side of the pressure-holding piston. Low-pressure nitrogen is filled into the low-pressure nitrogen chamber to seal and block the connection between the top fluid flow circuit and the top fluid release chamber. To facilitate the connection between the low-pressure nitrogen chamber, the trigger slide valve, and the top liquid release chamber, the low-pressure nitrogen chamber includes a gas body. The upper part of the gas chamber body is threadedly sealed to the trigger slide valve, and an upper piston is provided on the lower side. A linkage plug for sealing the top liquid flow circuit is provided below the upper piston. The lower outer periphery of the gas chamber body is threadedly connected to the top liquid release chamber. A central channel forming the top liquid flow circuit is provided in the center of the gas chamber body, and the upper interface of the central channel is sealed and fitted with the upper linkage plug. The lower part of the gas chamber body has a low-pressure nitrogen injection port and a low-pressure nitrogen inlet channel communicating with the low-pressure nitrogen chamber from the side. The trigger slide valve includes a valve seat. The lower side of the valve seat extends into the gas chamber body and is threadedly sealed. The extended portion of the valve seat and the interior of the gas chamber body have a low-pressure nitrogen release channel communicating with the top liquid release chamber and a first top liquid release channel. Release circuit; the low-pressure nitrogen chamber, through an internal linkage plug, uses the pressure of the low-pressure nitrogen gas to seal the passage between the top liquid flow circuit and the top liquid release chamber, preventing the top liquid from being released; the center of the slide valve seat is provided with a slide valve hole, the section of the slide valve hole is provided with a stepped part, the slide valve hole is provided with a slide valve rod and a compression spring, the upper end of the slide valve rod of the compression spring is provided with a pressing shoulder, the lower end of the compression spring is supported on the upper side of the stepped part, the slide valve hole below the stepped part and the slide valve rod are sequentially separated by a sealing ring assembly to provide a first valve chamber and a second valve chamber. When the slide valve rod moves up to the upper side of the first valve chamber, the first valve chamber and the second valve chamber are connected, and at the same time the low-pressure nitrogen release channel connected to the first valve chamber and the low-pressure nitrogen release channel connected to the second valve chamber are connected, and pressure is released to the top liquid release chamber, the upper piston and the linkage plug move up, and the central channel of the top liquid flow circuit opens to release the top liquid; To facilitate the installation of a top liquid flow circuit in the top liquid release chamber, a top liquid upper pipeline connected to the top liquid flow circuit is provided in the top liquid release chamber. The upper part of the top liquid upper pipeline is connected to the central channel of the gas chamber body, and the lower part is connected to the top liquid flow circuit provided in the top liquid safety valve. To facilitate the release of top fluid due to increased downhole pressure caused by high temperature, a top fluid safety valve is installed. This valve releases top fluid exceeding a preset pressure value and includes a first valve seat, a first valve core, and a first valve cover. The first valve seat contains a first top fluid channel connected to the top fluid flow circuit and an upper branch for releasing top fluid. The upper branch is connected to a top fluid release chamber. The first valve core is used to elastically seal the lower branch. The first top fluid channel extends downwards to the lower part of the first valve seat and connects to the bottom top fluid pipeline. The first valve seat also contains a high-pressure nitrogen inlet branch and an injection port connected to a high-pressure nitrogen chamber. The bottom top fluid pipeline is located within the high-pressure nitrogen chamber. When the top fluid pressure rises to a level that overcomes the upward movement of the first valve core, the first valve core opens the top fluid release branch, releasing a portion of the top fluid.

[0005] The high-pressure nitrogen release slide valve assembly includes a second valve cover, a second valve stem, and a second valve seat. The second valve cover is threadedly sealed to the lower part of the high-pressure nitrogen chamber. The second valve stem is disposed within the second valve seat. A compression spring and a spring cover are provided on the upper part of the second valve stem. The center of the second valve seat has a mounting hole for through-mounting the second valve stem. Between the second valve stem and the mounting hole, from top to bottom, there are sequentially arranged a sealing section, a guide section, and a second valve stem drive section. The annular space corresponding to the sealing section is divided into an upper cavity and a lower cavity by a sealing assembly. The upper cavity has a high-pressure gas supply line in the radial direction of the second valve seat and inside the valve cover that communicates with the upper high-pressure nitrogen chamber. The nitrogen upper branch has a top interface at the center of the upper part of the second valve cover that connects to the top liquid lower pipeline. A second top liquid channel is provided between the top interface and the lower cavity. The second valve seat has a top liquid injection port, a third top liquid channel that communicates with the top liquid injection port and extends downward, and a fourth top liquid channel that communicates with the second top flow channel. The third top liquid channel and the fourth top flow channel extend downward to the lower side of the second valve seat and communicate with the lower cavity. The second valve stem is triggered to move upward under the push of the lower power, so that the upper cavity and the lower cavity are connected, and the high-pressure nitrogen chamber and the lower pressure holding chamber are connected to achieve pressure holding of the sampling chamber after sampling. The pressure-holding chamber triggering component is used to trigger the valve stem of the high-pressure nitrogen release slide valve component after sampling is completed, so that the upper chamber and the lower chamber are connected and the high-pressure nitrogen is connected to the pressure-holding chamber, while isolating the top liquid downwards; The sampling chamber triggering component is triggered by the upward-moving pressure-holding piston after sampling is completed, so as to interlock the triggering action of the pressure-holding chamber triggering component; The sampling chamber valve core assembly is used to close the sampling port after sampling is completed.

[0006] Furthermore, in the structure of the top liquid safety valve, the first valve seat and the first valve cover are threadedly connected, and an internal space is provided for installing the first valve core. The first valve core includes a valve needle, a compression spring, a spring seat, and a spring sleeve. The spring sleeve limits and presses the spring seat, the compression spring, and the valve needle from the upper side. The center of the spring sleeve is provided with a guide hole that guides and limits the upper end of the spring seat. The upper end of the spring seat is provided with a limiting guide rod. The lower part of the valve needle is sealed with the interface of the branch liquid release branch. The internal space of the first valve core is connected to the first top liquid channel. The first valve cover is also provided with a top liquid channel that is connected to the top liquid upper pipe 5.

[0007] Furthermore, the second valve stem corresponding to the lower cavity has a reduced diameter section. The reduced diameter section extends downward to the lower end of the stem. When the second valve stem is triggered to move upward, the reduced diameter section moves upward to the upper side of the upper cavity to realize the connection between the upper cavity and the lower cavity, so as to connect the high-pressure nitrogen upper branch. The second valve seat has a high-pressure nitrogen lower branch that communicates with the lower cavity and extends downward to the lower side of the second valve seat.

[0008] Further, the pressure-holding trigger assembly includes a trigger plug, a sliding sleeve support ring, a sliding sleeve, and a sliding sleeve trigger body. The pressure-holding trigger assembly has an outer sleeve on its outer periphery. The upper part of the outer sleeve is threadedly sealed to the lower outer periphery of the second valve seat, and the upper inner periphery of the outer sleeve is threadedly connected to the sliding sleeve support ring. An outer support spring is provided on the middle outer periphery of the sliding sleeve support ring, supporting the upper end of the sliding sleeve and the middle of the sliding sleeve support ring. An inner convex guide ring is provided on the upper inner periphery of the sliding sleeve, axially sliding with the outer periphery of the sliding sleeve support ring. A limiting stop ring for axially limiting the inner convex guide ring is provided on the lower outer periphery of the sliding sleeve support ring. A guide rod section is provided at the lower part of the trigger plug, axially sliding with the sliding sleeve support ring. The upper side of the limiting stop ring has several steel ball holes circumferentially on the sliding sleeve support ring. The guide rod section has several corresponding recesses circumferentially on the steel ball holes. Each steel ball hole and recess is fitted with a steel ball, which is used for... The axial movement of the limiting trigger plug is achieved. An inner support spring for abutting the trigger plug is provided between the guide rod section on the upper side of the recess and the sliding sleeve support ring. The upper part of the trigger plug and the sliding sleeve support ring is provided with a guide section for axial sliding engagement. The sliding sleeve trigger body is fixed to the lower part of the sliding sleeve. The pressure holding chamber trigger assembly is provided with a fitting gap and channel to facilitate the connection of top liquid or high-pressure nitrogen. The upper side of the trigger plug is provided with a push rod that abuts against the second valve stem. The lower end of the second valve seat is provided with a sealing engagement part that seals with the trigger plug. The trigger plug abuts against the second valve stem. The upper side of the sealing engagement part between the second valve seat and the trigger plug is provided with a top liquid chamber that communicates with the fourth top liquid channel. When sampling is completed, the sliding sleeve trigger body is unlocked by the upward trigger steel ball. The trigger plug moves up and simultaneously pushes the second valve stem to move up to connect the upper and lower chambers, so that the upper branch of high-pressure nitrogen and the lower branch of high-pressure nitrogen are connected, while sealing and isolating the downward top liquid channel.

[0009] Furthermore, the sampling chamber includes a sampling chamber main tube column, the upper part of which is threadedly sealed to the lower part of the outer tube. The pressure-holding piston is fitted inside the sampling chamber main tube column, and a sampling chamber pull rod is slidably provided at the center of the pressure-holding piston. The upper end of the sampling chamber pull rod is connected to the sampling chamber triggering component. The sampling inlet is located on the lower side wall of the sampling chamber main tube column. The pressure-holding piston is located above the sampling inlet, and the pressure-holding chamber is located inside the sampling chamber main tube column above the pressure-holding piston. When the pressure-holding piston is pushed upward by the formation fluid to contact and trigger the sampling chamber triggering component, the sampling chamber triggering component and the pressure-holding chamber triggering component are triggered in conjunction, and the top liquid circuit and the high-pressure nitrogen chamber are connected to achieve pressure holding in the sampling chamber.

[0010] To facilitate the transmission of the sampling combination trigger action after sampling, the sampling chamber trigger assembly is located on the upper part of the main tube column of the sampling chamber. It includes a trigger rod, a trigger slide, a trigger sleeve, a trigger spring, and a trigger nut. The trigger rod passes through the central hole of the trigger slide. The lower outer circumference of the trigger slide is axially slidably sleeved with the upper inner circumference of the trigger sleeve. The trigger slide corresponding to the sliding section is provided with a limiting hole and a limiting steel ball around its circumference. The corresponding circumference of the trigger rod is provided with a limiting recess. The trigger nut is threadedly connected to the lower part of the trigger sleeve. A trigger spring is provided between the lower part of the trigger rod and the trigger nut. The trigger nut can be triggered by the upward-moving pressure-holding piston, which pushes the trigger rod upward.

[0011] To facilitate sampling and locking after sampling, the sampling chamber valve core assembly is located at the lower part of the sampling chamber main tube column, including a sampling valve core located below the pressure-holding piston. The upper center of the sampling valve core is threadedly connected to the sampling chamber pull rod. A sealing ring is fixed to the inner wall of the sampling chamber main tube column below the sampling inlet. The inner radial diameter of the sampling chamber main tube column below the sampling inlet is expanded outward to facilitate the inner diameter of the ring after installation of the sealing ring to match the inner diameter of the sampling chamber main tube column above the sampling inlet. The upper outer circumference of the sampling valve core has one or more sealing grooves for installing a sealing ring, and the sealing groove is fitted with a sealing ring and a retaining ring; the lower outer circumference of the sampling valve core has a variable diameter outer step to facilitate the sliding fit between the lower part of the sampling valve core and the inner diameter expansion section of the lower part of the sampling chamber main column; after the sampling valve core is pulled upward by the sampling chamber pull rod, the part corresponding to the sealing groove moves from the position corresponding to the sealing ring protection ring to the upper side of the sampling inlet to seal the sampling inlet and end the sampling.

[0012] To facilitate the positioning of the sampling valve core after locking and sampling, a limiting locking hole is provided in the sampling valve core in the horizontal direction perpendicular to the central axis. The limiting locking hole radially penetrates the sampling valve core. A limiting spring is pressed into the limiting pressure block at both ends of the limiting locking hole, which opens and closes in opposite directions. A limiting groove is provided in the radial direction corresponding to the main tube of the sampling chamber to limit the upper limit position of the sampling valve core. The locking end of the limiting pressure block is engaged with the limiting groove to limit the position of the sampling valve core.

[0013] To facilitate sample transfer above the well, a sample transfer interface is provided at a horizontal position below the outer step of the variable diameter of the sampling valve core. The sample transfer interface is sealed by a plug. A discharge hole communicating with the sampling chamber is provided axially perpendicular to the sample transfer interface. A valve hole is provided on the lower side of the discharge hole, and a sampling valve needle is threaded into the valve hole. When the sampling valve core is pulled to the upper limit position by the sampling chamber pull rod, a sample transfer hole is provided on the side wall of the main tubing of the sampling chamber corresponding to the sample transfer interface.

[0014] To reduce sampling impurities, a filter screen is installed at the inlet of the sampling port; the lower end of the main tube of the sampling chamber is provided with a lower end that communicates with the formation.

[0015] The high-temperature, high-pressure downhole pressure-holding sampler of this invention mainly includes a low-pressure nitrogen chamber, a top fluid release chamber, a top fluid safety valve, a high-pressure nitrogen chamber, a sampling chamber, and a multi-stage interlocking trigger assembly (mainly referring to the nitrogen release slide valve assembly, the pressure-holding chamber trigger assembly, the sampling chamber trigger assembly, and the sampling chamber valve core assembly). The top fluid is supplied to the upper side of the pressure-holding piston in the sampling chamber to pressurize the piston and prevent non-target well depth fluid from prematurely entering the sampling chamber during the downhole process. The low-pressure nitrogen chamber is pre-filled with low-pressure nitrogen at a certain pressure to seal the pre-filled top fluid and prevent leakage to the top fluid release chamber. The top fluid release chamber contains atmospheric pressure air to receive the released top fluid medium. The top fluid safety valve automatically releases pressure when the pressure of the top fluid exceeds a set value due to high formation temperature, and closes the valve while maintaining a minimum pressure greater than the formation pressure. The high-pressure nitrogen chamber is pre-filled with nitrogen compared to the sampled formation. High-pressure nitrogen gas with a pressure of 10-15 MPa is used to maintain the pressure in the sampling chamber after sampling through a multi-stage interlocking trigger assembly. This prevents the pressure in the sampling chamber from decreasing after the temperature drops. The pressure-maintaining chamber trigger assembly is used to trigger the release of high-pressure nitrogen gas. The pressure-maintaining piston moves to sample under the pressure difference between the formation pressure and the top fluid pressure, isolating the top fluid and the formation sample and maintaining the pressure. The sampling chamber trigger assembly is used to control the sampling chamber valve core assembly to close the sampling port and trigger the pressure-maintaining chamber trigger assembly. The sampling chamber valve core assembly is used to seal the liquid inlet of the sampling chamber after sampling.

[0016] Therefore, the beneficial effects of the above-mentioned high-temperature and high-pressure downhole pressure-holding sampler of the present invention are as follows: through the low-pressure nitrogen circuit, the high-pressure nitrogen circuit, the top fluid circuit, and the multi-stage interlocking triggering components, deep high-temperature and high-pressure formation sampling is realized, and the pressure of the sampling chamber is maintained during the lifting process after sampling, so as to achieve more accurate high-pressure physical property research on the formation sample. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the high-temperature and high-pressure downhole pressure-maintaining sampler of the present invention (before triggering).

[0018] Figure 2 for Figure 1 A schematic diagram of the structure of section A.

[0019] Figure 3 for Figure 1 A structural diagram of section B.

[0020] Figure 4 is Figure 1 A schematic diagram of the structure of segment C.

[0021] Figure 5 This is a schematic diagram of the pressure-holding chamber trigger assembly.

[0022] Figure 6 This is a schematic diagram of the sampling chamber trigger component.

[0023] Figure 7 This is a schematic diagram of the sampling chamber valve core assembly.

[0024] Figure 8 for Figure 7 Cross-sectional view along the middle GG.

[0025] Figure 9 This is a schematic diagram of the high-temperature and high-pressure downhole pressure-maintaining sampler after it has been triggered.

[0026] Among them, 1 is a trigger slide valve; 101 is a slide valve rod; 102 is a compression spring; 103 is a sealing ring assembly; 104 is a first valve chamber; 105 is a second valve chamber; 106 is a low-pressure nitrogen release channel; 2 is a low-pressure nitrogen chamber; 201 is the main body of the chamber; 202 is a low-pressure nitrogen inlet channel; 203 is a low-pressure nitrogen injection port; 204 is a low-pressure nitrogen release channel; 205 is a first top liquid release circuit; 206 is a central channel; 3 is an upper piston; 4 is a top liquid release chamber; 5 is a top liquid upper pipeline; 6 is a top liquid safety valve; 601 is a first valve cover; 602 is a valve core; 602A is a valve needle; 602B is a compression spring; 602C is a spring seat; 602D is a spring sleeve; 603 is a top liquid release upper branch; 604 is a top liquid release lower branch; 605 is a first valve seat; 606 is a high-pressure nitrogen inlet branch; 607 is a high-pressure nitrogen injection port; 608 is a first top liquid channel; 609 is a top liquid upper channel; 7 is a low-pressure nitrogen chamber; 8. High-pressure nitrogen chamber; 8. High-pressure nitrogen release slide valve assembly; 801. Second valve cover; 802. High-pressure nitrogen upper branch; 803. Spring cover; 804. Compression spring; 805. Upper chamber; 806. Sealing assembly; 807. Lower chamber; 808. Second valve seat; 809. Top liquid injection port; 810. Second valve stem; 811. Fourth top liquid channel; 812. Third top liquid channel; 813. High-pressure nitrogen lower branch; 814. Top liquid chamber; 9. Pressure holding chamber trigger assembly; 901. Trigger plug; 902. Sealing ring; 903. Sliding sleeve support seat; 904. Inner support spring; 905. Outer support spring; 906. Steel ball; 907. Sliding sleeve; 908. Limiting ring; 909. Sliding sleeve trigger body; 910. Outer sleeve; 10. Sampling chamber trigger assembly; 1001 Top rod; 1002 Trigger slide; 1003 Limiting steel ball; 1004 Trigger sleeve; 1005 Trigger spring; 1006 Trigger nut; 11 Sampling chamber pull rod; 12 Sampling chamber; 1201 Sampling chamber main column; 1202 Sample inlet; 1203 Filter screen; 1204 Pressure holding chamber; 13 Pressure holding piston; 14 Sampling chamber valve core assembly; 1401 Sealing ring; 1402 Retaining ring; 1403 Sealing ring protection ring; 1404 Sampling valve core; 1405 Sample transfer interface; 1406 Sampling valve needle; 1407 Limiting lock hole; 1408 Sample discharge hole; 1409 Limiting spring; 1410 Limiting pressure block; 15 Lower end. Detailed Implementation

[0027] The specific structure and implementation method of the high-temperature and high-pressure downhole pressure-maintaining sampler of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] like Figures 1 to 9 As shown, this is the high-temperature and high-pressure downhole pressure-maintaining sampler of the present invention, wherein... Figures 1-8 The sampler and the structure of each segment are in the state before triggering. Figure 9 This is the state after the sampler completes downhole sampling and the chain is triggered.

[0029] like Figure 1 As shown, the high-temperature and high-pressure downhole pressure-holding sampler of the present invention includes, from top to bottom, a trigger slide valve 1, a low-pressure nitrogen chamber 2, a top fluid release chamber 4, a top fluid safety valve 6, a high-pressure nitrogen chamber 7, a high-pressure nitrogen release slide valve assembly 8, a pressure-holding chamber trigger assembly 9, a sampling chamber trigger assembly 10, a sampling chamber 12, a pressure-holding piston 13, a sampling chamber valve core assembly 14, and a lower end 15. A top fluid flow circuit (composed of multiple channels or pipelines of different pipe sections) is provided between the upper side of the pressure-holding piston 13 and the top fluid release chamber 4. The sampling chamber 12 is provided with a sampling inlet 1202 communicating with the formation. The pressure-holding piston 13 is located in the sampling chamber 12. A pressure-holding chamber 1204 for alternating action of top fluid and high-pressure nitrogen is provided on the upper side of the pressure-holding piston 13. Low-pressure nitrogen is filled into the low-pressure nitrogen chamber 2 to seal and block the connection between the top fluid flow circuit and the top fluid release chamber 4. like Figure 2As shown, the low-pressure nitrogen chamber 2 of the present invention includes a gas body 201. The upper part of the gas chamber body 201 is threadedly sealed to the trigger slide valve 1, and the lower side is provided with an upper piston 3. The lower part of the upper piston 3 is provided with a linkage plug for blocking the top liquid flow circuit. The lower outer periphery of the gas chamber body 201 is threadedly connected to the top liquid release chamber 4. The center of the gas chamber body 201 is provided with a central channel 206 forming the top liquid flow circuit, and the upper interface of the central channel 206 is sealed and mated with the upper linkage plug. The lower part of the gas chamber body 201 is laterally provided with a connection to the low-pressure... The nitrogen chamber 2 is connected to a low-pressure nitrogen injection port 203 and a low-pressure nitrogen inlet channel 203. The low-pressure nitrogen injection port 203 is generally sealed with a plug. Before construction, when injecting gas on the ground, the plug is opened to connect the low-pressure nitrogen pipeline, and gas is injected to overcome the pressure of P1. After the gas injection is completed, the gas injection pipeline is cut off and the injection port is sealed. The trigger slide valve 1 of the present invention includes a slide valve seat 107. The lower side of the slide valve seat 107 extends into the gas chamber body 201 and is threaded and sealed. The extension part of the slide valve seat 107 and the interior of the gas chamber body 201 are provided with a connection to the top liquid. Release chamber 4 is connected to low-pressure nitrogen release channel 106 and first top liquid release circuit 205; low-pressure nitrogen chamber 2, through an internal linkage plug, uses the pressure of the filled low-pressure nitrogen to seal the passage between the top liquid flow circuit and top liquid release chamber 4, preventing top liquid release; the center of the slide valve seat 107 is provided with a slide valve hole, the section of the slide valve hole is provided with a stepped part, the slide valve hole is provided with a slide valve rod 101 and a compression spring 102, the upper end of the slide valve rod 101 of the compression spring 102 is provided with a pressing shoulder, the lower end of the compression spring 102 is supported on the upper side of the stepped part, the stepped part is... The lower slide valve hole and the slide valve rod 101 are sequentially separated by the sealing ring assembly 103, providing a first valve chamber 104 and a second valve chamber 105. When the slide valve rod 101 moves up to the upper side of the first valve chamber 104, the first valve chamber 104 and the second valve chamber 105 are connected, thereby connecting the low-pressure nitrogen release channel 204 connected to the first valve chamber 104 and the low-pressure nitrogen release channel 106 connected to the second valve chamber, and depressurizing to the top liquid release chamber 4. The upper piston 3 and the linkage plug move up, and the central channel 206 of the top liquid flow circuit opens to release the top liquid.

[0030] like Figure 1 As shown, in order to facilitate the installation of a top liquid flow circuit in the top liquid release chamber, a top liquid upper pipeline 5 connected to the top liquid flow circuit is provided in the top liquid release chamber 4. The upper part of the top liquid upper pipeline 5 is connected to the central channel 204 of the gas chamber body, and the lower part is connected to the top liquid flow circuit provided in the top liquid safety valve 6.

[0031] like Figure 3As shown, the top liquid safety valve 6 is used to release top liquid exceeding a preset top liquid pressure value. It includes a first valve seat 605, a first valve core 602, and a first valve cover 601. The first valve seat 605 has a first top liquid channel 608 connected to the top liquid flow circuit, and a lower top liquid release branch 604 and an upper top liquid release branch 603 for releasing top liquid. The upper top liquid release branch 603 is connected to the top liquid release chamber. The first valve core 602 is used to elastically seal the lower top liquid release branch 604. The first top liquid channel 608 extends downward to the lower part of the first valve seat 605 and connects to the lower top liquid pipeline in the high-pressure nitrogen chamber 7. The first valve seat 605 also has a high-pressure nitrogen inlet branch 606 and a high-pressure nitrogen injection port 607. When the top liquid pressure rises to overcome the upward movement of the first valve core 602, the first valve core 602 opens the lower top liquid release branch 604. The first valve cover 601 has a cavity inside its lower side. The connected upper branch 603 for top liquid release allows the top liquid released from the lower branch 604 to enter the top liquid release chamber 4 via the aforementioned cavity. The first valve seat 605 and the first valve cover 601 are threaded together, and the first valve seat 605 has an internal space for installing the first valve core 602. The first valve core 602 includes a valve needle 602A, a compression spring 602B, a spring seat 602C, and a spring sleeve 602D. The spring sleeve 602D extends from the top... The system includes a limiting and fixing spring seat 602C, a compression spring 602B, and a valve needle 602A. The center of the spring sleeve 602D is provided with a guide hole at the upper end of the limiting spring seat 602C. The upper end of the spring seat 602C is provided with a limiting guide rod. The lower part of the valve needle 602A is sealed with the interface of the top liquid release lower branch 604. The internal space of the first valve core 602 is connected to the first top liquid channel 608. The first valve cover is also provided with a top liquid upper channel 609 connected to the top liquid upper pipe 5. In the structure of the top liquid safety valve 6 described above, the top liquid upper channel 609 is connected to the top liquid upper pipeline 5, and the first top liquid channel 608 is connected to the top liquid lower pipeline. Both the top liquid upper channel 609 and the first top liquid channel 608 are connected to the space between the first valve seat 605 and the first valve core, forming a normal top liquid flow circuit within the top liquid safety valve 6. Under the action of the pressure spring 602B, the valve needle 602A isolates the top liquid flow circuit from the top liquid release lower branch. When the pressure in the top liquid flow circuit is too high, after overcoming the elastic force of the pressure spring 602B, the valve needle 602A moves upward, opening the top liquid release lower branch 604 to achieve safe pressure relief and discharge of liquid to the top liquid release chamber 4, until the pressure is reduced to below the pressure that can reset the pressure spring and the top liquid release lower branch 604 is closed.

[0032] like Figure 4As shown, the high-pressure nitrogen release slide valve assembly 8 includes a second valve cover 801, a second valve stem 810, and a second valve seat 808. The second valve cover 801 is threadedly sealed to the lower part of the high-pressure nitrogen chamber 7. The second valve stem 810 is disposed inside the second valve seat 808, and a compression spring 804 and a spring cover 803 are provided on the upper part of the second valve stem 810. The second valve seat 808 has a mounting hole at its center for through-mounting the second valve stem 810. The second valve stem 810 and the mounting hole are connected sequentially from top to bottom. The valve has a sealing section, a guide section, and a second valve stem drive section. The annulus corresponding to the sealing section is divided into an upper cavity 805 and a lower cavity 807 by a sealing assembly 806. The lower cavity 807 has a reduced-diameter section on the rod of the second valve stem 810, which extends downward to the lower end of the stem. When the second valve stem 811 is triggered to move upward, the reduced-diameter section moves upward to the upper side of the upper cavity, thus connecting the upper cavity 805 and the lower cavity 807. The upper cavity 805 has a second valve seat 808 radially connected to the valve cover 80. The second valve seat 808 has a high-pressure nitrogen upper branch line 802 connected to the upper high-pressure nitrogen chamber 7; the second valve seat 808 has a high-pressure nitrogen lower branch line 813 connected to the lower chamber 807 and extending downward to the lower side of the second valve seat 808; the upper center of the second valve cover 801 has a top interface connected to the top liquid lower pipeline, and a second top liquid channel 809 is provided between the top interface and the lower chamber 807; the second valve seat 808 has a top liquid injection port 809, and a channel 809 connected to the top liquid injection port 809 is provided. The third top liquid channel 812 extends downward and the fourth top liquid channel 811 communicates with the second top flow channel 809. The third top liquid channel 812 and the fourth top flow channel 811 respectively penetrate downward to the lower side of the second valve seat 808 and communicate with the lower cavity. The second valve stem 810 can be triggered to move upward under the push of the lower power to connect the upper cavity 805 and the lower cavity 807, and connect the high-pressure nitrogen chamber 7 and the lower pressure holding chamber 1204 to achieve pressure holding of the sampling chamber after sampling. The high-pressure nitrogen release slide valve assembly 8 described above, with the second top liquid channel 809, lower chamber 807, fourth top liquid channel 811, and third top liquid channel 809 forming the top liquid flow circuit of this section; when not triggered during the well run-in process until the end of sampling, the upper chamber 805 and lower chamber 807 are separated and not connected, that is, not connected to the high-pressure nitrogen upper branch 802. When sampling ends, the trigger assembly triggers the second valve rod 810 to move upward, and the lower chamber 807 connects with the upper chamber 805, and the top liquid flow circuit connects with the high-pressure nitrogen upper branch 802, until it connects to the lower pressure holding chamber 1204, realizing pressure holding of the pressure holding piston and sampling chamber.

[0033] like Figure 5As shown, the pressure holding chamber trigger assembly 9 is used to trigger the second valve stem 810 of the high-pressure nitrogen release slide valve assembly 8 after sampling, so as to connect the upper chamber 805 and the lower chamber 807 and then connect the high-pressure nitrogen to the pressure holding chamber 1204. Specifically, the pressure holding trigger assembly 9 includes a trigger plug 901, a sliding sleeve support ring 903, a sliding sleeve 907, and a sliding sleeve trigger body 909. The pressure holding trigger assembly is provided with an outer sleeve 910. The upper part of the outer sleeve 910 is threadedly sealed to the lower outer periphery of the second valve seat 808, and the upper inner periphery of the outer sleeve 910 is threadedly connected to the sliding sleeve support ring 903. The middle outer periphery of the sliding sleeve support ring 903 is provided with an outer support spring 905, which is supported on the upper end of the sliding sleeve 907 and the middle part of the sliding sleeve support ring 903. The upper inner periphery of the sliding sleeve 907 is provided with an inner protrusion that slides axially with the outer periphery of the sliding sleeve support ring 903. The lower outer periphery of the guide ring and the sliding sleeve support ring 903 is provided with a limiting stop ring 908 for axially limiting the inner convex guide ring; the lower part of the trigger plug 901 is provided with a guide rod section, which is axially slidingly engaged with the sliding sleeve support ring 903. The upper side of the limiting stop ring 908 of the sliding sleeve support ring 903 is provided with several steel ball holes in the circumference, and the guide rod section is provided with several recesses in the circumference corresponding to the steel ball holes. The steel ball holes and recesses are matched one-to-one and fitted with steel balls 906. The steel balls 906 are used to limit the axial movement of the trigger plug 901. The upper side of the recess of the guide rod section and the sliding sleeve support ring 903 is provided with an inner support spring for abutting against the trigger plug 901. Spring 904, trigger plug 901 and upper part of sliding sleeve support ring 903 are provided with guide section for axial sliding fit; sliding sleeve trigger body 909 is fixed to the lower part of sliding sleeve, and the inside of pressure holding chamber trigger assembly 9 is provided with fitting gap and channel to facilitate connection of top liquid or high pressure nitrogen; upper side of trigger plug 901 is provided with push rod that abuts against second valve stem 809, lower end of second valve seat 808 is provided with sealing fit part and sealing ring 902 that seals with trigger plug 901, trigger plug 901 abuts against second valve stem 810, upper side of sealing fit part of second valve seat 808 and trigger plug 901 is provided with passage for fourth top liquid. The top liquid chamber 814, which is connected to channel 811, is specifically an annular space between the lower second push rod 808 and the push rod trigger docking section of the trigger plug. This space is sealed after the trigger plug 901 moves upward and seals the lower part of the second valve seat 808. When sampling is completed, the sliding sleeve trigger body 909 is unlocked by the upward trigger steel ball, the trigger plug 901 moves upward and simultaneously pushes the second valve rod 810 to move upward to connect the upper and lower chambers, so that the high-pressure nitrogen upper branch 802 and the high-pressure nitrogen lower branch are connected 813. At the same time, the trigger plug seals and isolates the top liquid chamber 814 to isolate the downward top liquid channel.

[0034] Used to trigger the upward movement of the second valve stem, thereby triggering the high-pressure nitrogen release slide valve assembly 8; when sampling ends, the sliding sleeve trigger body 909 is pushed and triggered by the trigger member on the lower side, and pushes the sliding sleeve 907 to unlock the steel ball 906 from the pit, the sliding sleeve 907 moves upward, the trigger plug 907 moves upward and simultaneously pushes the second valve stem 810 to trigger upward, thereby triggering the high-pressure nitrogen release slide valve assembly, connecting the pressure holding chamber and the high-pressure nitrogen upper branch, and isolating the top liquid channel downward.

[0035] like Figure 6 As shown, the sampling chamber trigger assembly 10 of the present invention is triggered by the upward-moving pressure-holding piston 13 after sampling, so as to interlock the triggering action of the pressure-holding chamber trigger assembly 9 and the high-pressure nitrogen slide valve assembly 8. Specifically, the sampling chamber trigger assembly 10 is located on the upper part of the sampling chamber main tube column 1201, and includes a trigger rod 1001, a trigger slide 1002, a trigger sleeve 1004, a trigger spring 1005, and a trigger nut 1006. The trigger rod 1001 passes through the central hole of the trigger slide 1002. The lower outer periphery of the trigger slide 1002 is axially slidably sleeved with the upper inner periphery of the trigger sleeve 1004, and the circumference of the trigger slide corresponding to the sliding section is provided with a limiting hole and a limiting steel ball 1003. The corresponding circumference of the trigger rod 1001 is provided with a limiting recess for locking the position of the limiting steel ball and the trigger rod 1001. The trigger nut 10065 is threadedly connected to the lower part of the trigger sleeve 1004. A trigger compression spring 1005 is provided between the lower part of the trigger rod 1001 and the trigger nut 1006. The trigger nut 1006 can be pushed by the pressure holding piston 13 after it moves up and push the trigger sleeve 1004 to move up, the limiting steel ball 1003 is unlocked, and the trigger rod moves up to trigger the upper pressure holding chamber trigger assembly.

[0036] like Figure 7 The sampling chamber 12 of the present invention includes a sampling chamber main tube column 1201. The upper part of the sampling chamber main tube column 1201 is threadedly sealed to the lower part of the outer sleeve 910. A pressure-holding piston 13 is fitted inside the sampling chamber main tube column 1201. A sampling chamber pull rod 11 is slidably provided at the center of the pressure-holding piston 13. The upper end of the sampling chamber pull rod 11 is connected to the lower end of the trigger rod 1001 of the sampling chamber trigger assembly 10. The sampling inlet 1202 is disposed on the lower side wall of the sampling chamber main tube column 1201. The pressure-holding piston 13 is located at the sampling inlet 1202. On the upper side of 201, the pressure holding chamber 1204 is located inside the sampling chamber main column 1201 above the pressure holding piston 13. When the pressure holding piston 13 is pushed upward by the formation fluid to contact and trigger the sampling chamber triggering component 10, the sampling chamber triggering component 10 and the pressure holding chamber triggering component 9 are triggered in conjunction, and the top liquid circuit and the high-pressure nitrogen chamber 7 are connected to achieve pressure holding of the sampling chamber 12. In order to reduce sampling impurities, the inlet of the sampling inlet 1202 is equipped with a filter screen 1204. The lower end of the sampling chamber main column 1201 is provided with a lower end head 15 that communicates with the formation.

[0037] The sampling chamber valve core assembly 14 is used to close the sampling port after sampling. Specifically, the sampling chamber valve core assembly 14 is located at the lower part of the sampling chamber main column 1201, including a sampling valve core 1404 located below the pressure holding piston 13. The upper center of the sampling valve core 1404 is threadedly connected to the sampling chamber pull rod 11. A sealing ring protection ring 1403 is fixed on the inner wall of the sampling chamber main column 1201 below the sampling inlet 1202. The inner radial diameter of the sampling chamber main column 1201 below the sampling inlet 1202 is expanded outward to facilitate the inner diameter of the ring after the sealing ring protection ring 1403 is installed to match the sampling port above the sampling inlet 1202. The main tubing of the sampling chamber has the same inner diameter. The upper outer periphery of the sampling valve core 1404 is provided with one or more sealing grooves for installing the sealing ring assembly. The sealing groove is equipped with the sealing ring 1401 and the retaining ring 1402. The lower outer periphery of the sampling valve core 1404 is provided with a variable diameter outer step to facilitate the sliding fit between the lower part of the sampling valve core 1404 and the inner diameter expansion section of the lower part of the sampling chamber main tubing 1201. After the sampling valve core 1404 is pulled upward by the sampling chamber pull rod 11, the part corresponding to the sealing groove moves from the position corresponding to the sealing ring protection ring 1403 to the upper side of the sampling inlet 1202 to seal the sampling inlet 1202 and end the sampling.

[0038] like Figure 7 and Figure 8 As shown, to facilitate locking the position of the sampling valve core 1404 after sampling, a limiting locking hole 1407 is provided in the horizontal direction perpendicular to the central axis inside the sampling valve core 1404. The limiting locking hole 1407 radially penetrates the sampling valve core 1404. A limiting pressure block 1410 with opposite opening and closing at both ends is press-fitted with a limiting spring 1409 inside the limiting locking hole 1407. A limiting groove is provided in the radial direction corresponding to the sampling chamber main tube column 1201 to limit the upper limit position of the sampling valve core 1404. The locking end of the limiting pressure block 1401 is engaged with the limiting groove to limit the position of the sampling valve core 1404. After sampling is completed, the pressure-holding piston 13 is pushed upward by the formation fluid in the sampling chamber until it contacts the trigger nut and pushes the trigger nut, triggering the sampling chamber trigger assembly 10. At the same time, the sampling chamber pull rod 11 moves upward synchronously with the trigger push rod 1001 and drives the sampling valve core 1404 to move upward until the limit pressure block 1410 engages with the limit groove on the sampling chamber main column 1201, locking the sampling valve core and stopping its upward movement. The sealing assembly of the sampling valve core (sealing ring 1401 and retaining ring 1402) moves upward to seal with the inner wall of the sampling chamber main column 1201 above the sampling inlet 1202, cutting off the liquid inlet of the sampling inlet, i.e. closing the sampling port. All triggering actions are completed, and the entire sampler can be lifted to the ground.

[0039] To facilitate sample transfer from the sampling chamber after being lifted to the surface, a sample transfer interface 1405 is provided at a horizontal position below the outer step of the variable diameter of the sampling valve core 1404. The sample transfer interface 1405 is sealed by a plug. A discharge hole 1408 communicating with the sampling chamber is provided axially perpendicular to the sample transfer interface 1405. A valve hole is provided on the lower side of the discharge hole 1408, and a sampling valve needle 1406 is threaded into the valve hole. When the sampling valve core 1404 is pulled to the upper limit position by the sampling chamber pull rod, a sample transfer hole 1409 is provided on the side wall of the main tube of the sampling chamber corresponding to the sample transfer interface 1404. During sample transfer, the plug of the sample transfer interface 1405 communicates with the sample transfer equipment to transfer the sample.

[0040] Before sampling, the high-temperature and high-pressure downhole pressure-holding sampler of the present invention is assembled and connected according to the figure. The trigger slide valve 1 is connected to the trigger controller. The trigger controller can be a commonly used wall-mounted type, clock-controlled type, or electronic clock type trigger controller for downhole construction.

[0041] Before going down into the well, the low-pressure nitrogen injection port is pre-charged with low-pressure nitrogen up to 6 MPa, the high-pressure nitrogen injection port is pre-charged with high-pressure nitrogen 10-15 MPa higher than the sampled formation, the top liquid injection port is pre-charged with top liquid medium at the same pressure as the sampled formation, and the top liquid release chamber 4 is filled with atmospheric pressure air.

[0042] The low-pressure nitrogen chamber 2 is pre-filled with a certain amount of low-pressure nitrogen. The upper piston 3 seals the pre-filled high-pressure top fluid, preventing the top fluid from leaking into the top fluid release chamber 4. The pre-filled top fluid pressure is the same as the formation sampling pressure. The top fluid flows through the top fluid circulation loops of each section until it reaches the pressure holding chamber 1204 on the upper side of the pressure holding piston 13. This ensures that the pressure holding piston will not be pushed by the formation pressure force during the well run and will not be passively sampled. During the well run, due to the increase in formation temperature, the top fluid pressure will gradually increase with the increase in temperature. When the top fluid pressure rises above the pressure set by the top fluid safety valve 6, the top fluid safety valve 6 will automatically open to release the top fluid pressure to the safe pressure and automatically close the top fluid safety valve. The released top fluid flows through the top fluid release lower branch 604, the cavity on the lower side of the first valve cover 601, and the top fluid release upper branch 603 to the top fluid release chamber 4.

[0043] When the sampler reaches the target layer, it triggers the controller to move, which in turn triggers the slide valve 1 to lift the slide valve rod 101 upward. The first valve chamber 104 and the second valve chamber are connected, connecting the low-pressure nitrogen chamber release valves 204 (and 106) to release the nitrogen in the low-pressure nitrogen chamber to the top liquid release chamber, reducing its internal pressure. The upper piston moves upward and releases the top liquid at the same time. When the top liquid pressure is lower than the formation pressure, the pressure holding piston 13 will begin to slide upward and sample under the pressure difference between the formation pressure and the top liquid pressure. The top liquid will be released into the top liquid release chamber for continuous sampling. At this time, the upper chamber 805 and the lower chamber 807 of the high-pressure nitrogen release slide valve are not connected due to the action of the second valve rod 810 under the pressure spring 804. The high-pressure nitrogen is only connected to the upper chamber 805 and is blocked at the upper chamber.

[0044] When the pressure-holding piston 13 is lifted and moved to the maximum sampling capacity by the sampling liquid, the pressure-holding piston 13 will trigger the sampling chamber trigger assembly 10, releasing the limiting steel ball 1003 inside the trigger assembly. The pressure-holding piston 13 continues to move upward under the action of pressure difference. The pressure-holding piston 13 will push the trigger rod 1001 in the sampling chamber trigger assembly 10, together with the sampling chamber pull rod 11 and the sampling chamber valve core assembly 14, to move upward until the sampling chamber valve core assembly 14 enters the sampling chamber 12 and seals the sampling inlet 1202. The sampling chamber valve core assembly 14 moves upward until the limiting pressure block is locked with the limiting groove on the inner wall of the sampling chamber main tube 1201, so as to lock it in the position of the sampling valve core 1404 and not move. At this point, the formation sample sampling process is completed.

[0045] Simultaneously, after the above sampling is completed, when the pressure-holding piston 13 drives the sampling chamber trigger rod 1001 to move upward, the trigger rod 1001 will simultaneously trigger the sliding sleeve trigger body in the pressure-holding chamber trigger assembly 9 to push the sliding sleeve 907 upward, causing the steel ball 90 to unlock. The trigger plug 901 moves upward, and the trigger plug 901 will close the top liquid outlet in the pressure-holding chamber under the action of the inner support spring 904, providing a sealed space for the subsequent high-pressure nitrogen to provide pressure-holding function for the formation sample.

[0046] The trigger plug 901 moves upward under the action of the inner support spring 904, closing the connection between the top liquid chamber 814 and the lower part. At the same time, it also pushes the second valve stem 810 of the high-pressure nitrogen release slide valve assembly 8 to move upward, connecting the upper chamber 805 and the lower chamber 807, and connecting the high-pressure nitrogen with the pressure holding chamber 1202. This allows the pressure of the high-pressure nitrogen to act on the pressure holding piston to maintain the pressure of the sampled liquid in the sampling chamber below the piston, ensuring that the sample pressure in the sampling chamber does not change during the process of the sampler being lifted from the formation to the ground.

Claims

1. A high-temperature, high-pressure downhole pressure-holding sampler, comprising, from top to bottom, a trigger slide valve, a low-pressure nitrogen chamber, a top fluid release chamber, a top fluid safety valve, a high-pressure nitrogen chamber, a high-pressure nitrogen release slide valve assembly, a pressure-holding chamber trigger assembly, a sampling chamber trigger assembly, a sampling chamber, a pressure-holding piston, a sampling chamber valve core assembly, and a lower end, wherein a top fluid flow circuit is provided between the upper side of the pressure-holding piston and the top fluid release chamber; the sampling chamber is laterally provided with a sampling inlet communicating with the formation; the pressure-holding piston is located within the sampling chamber; a pressure-holding chamber for alternating action of top fluid and high-pressure nitrogen is provided on the upper side of the pressure-holding piston; and low-pressure nitrogen is filled into the low-pressure nitrogen chamber to seal and block the connection between the top fluid flow circuit and the top fluid release chamber; The low-pressure nitrogen chamber includes a gas body, the upper part of which is threadedly sealed to a trigger slide valve, and the lower side... The system includes an upper piston with a linkage plug at its lower part for sealing the top liquid flow circuit. The lower outer periphery of the gas chamber body is threadedly connected to the top liquid release chamber. The center of the gas chamber body has a central channel forming the top liquid flow circuit, and the upper interface of the central channel is sealed and fitted with the linkage plug on the upper side. The lower part of the gas chamber body has a low-pressure nitrogen injection port and a low-pressure nitrogen inlet channel communicating with the low-pressure nitrogen chamber from the side. The trigger slide valve includes a slide valve seat, the lower side of which fits into the gas chamber body and is threaded and sealed. The inserted part of the slide valve seat and the interior of the gas chamber body have a low-pressure nitrogen release channel and a first top liquid release circuit communicating with the top liquid release chamber. The low-pressure nitrogen chamber, through the internal linkage plug, utilizes the low-pressure nitrogen... Nitrogen pressure is used to seal the passage between the top liquid flow circuit and the top liquid release chamber to prevent top liquid release. The center of the slide valve seat is provided with a slide valve hole, and the section of the slide valve hole is provided with a stepped part. The slide valve hole is provided with a slide valve rod and a compression spring. The upper end of the slide valve rod of the compression spring is provided with a pressing shoulder, and the lower end of the compression spring is supported on the upper side of the stepped part. The slide valve hole below the stepped part and the slide valve rod are sequentially separated by a sealing ring assembly to provide a first valve chamber and a second valve chamber. When the slide valve rod moves up to the upper side of the first valve chamber, the first valve chamber and the second valve chamber are connected. At the same time, the low-pressure nitrogen release channel connected to the first valve chamber and the low-pressure nitrogen release channel connected to the second valve chamber are connected and depressurized to the top liquid release chamber. The upper piston and the linkage plug move up, and the central channel of the top liquid flow circuit is opened to release the top liquid. The top liquid release chamber is equipped with a top liquid upper pipeline connected to the top liquid flow circuit. The upper part of the top liquid upper pipeline is connected to the central channel of the gas chamber body, and the lower part is connected to the top liquid flow circuit set in the top liquid safety valve. The top liquid safety valve is used to release top liquid exceeding a preset top liquid pressure value. It includes a first valve seat, a first valve core, and a first valve cover. The first valve seat is provided with a first top liquid channel communicating with the top liquid flow circuit and a top liquid release lower branch and a top liquid release upper branch for high-pressure release of top liquid. The top liquid release upper branch is connected to the top liquid release chamber. The first valve core is used to elastically seal the top liquid release lower branch. The first top liquid channel extends downward to the lower part of the first valve seat and is connected to the top liquid lower pipeline. The first valve seat is also provided with a high-pressure nitrogen inlet branch and an injection port connected to the high-pressure nitrogen chamber. The top liquid lower pipeline is located in the high-pressure nitrogen chamber. The high-pressure nitrogen release slide valve assembly includes a second valve cover, a second valve stem, and a second valve seat. The second valve cover is threadedly sealed to the lower part of the high-pressure nitrogen chamber. The second valve stem is disposed within the second valve seat. A compression spring and a spring cover are provided on the upper part of the second valve stem. The center of the second valve seat has a mounting hole for through-mounting the second valve stem. Between the second valve stem and the mounting hole, from top to bottom, there are sequentially arranged a sealing section, a guide section, and a second valve stem drive section. The annular space corresponding to the sealing section is divided into an upper cavity and a lower cavity by a sealing assembly. The upper cavity has radial connections between the second valve seat and the valve cover, communicating with the upper high-pressure nitrogen chamber. The high-pressure nitrogen upper branch has a top interface at the center of the upper part of the second valve cover that connects to the top liquid lower pipeline. A second top liquid channel is provided between the top interface and the lower cavity. The second valve seat has a top liquid injection port, a third top liquid channel that communicates with the top liquid injection port and extends downward, and a fourth top liquid channel that communicates with the second top flow channel. The third top liquid channel and the fourth top flow channel are respectively connected to the top liquid cavity on the lower side of the second valve seat. After the second valve stem is triggered to move upward under the push of the lower power, the upper cavity and the lower cavity are connected, and the high-pressure nitrogen chamber and the lower pressure holding chamber are connected to achieve pressure holding of the sampling chamber after sampling. The pressure-holding chamber triggering component is used to trigger the valve stem of the high-pressure nitrogen release slide valve component after sampling is completed, so that the upper and lower chambers are connected and the high-pressure nitrogen is connected to the pressure-holding chamber, and the top liquid is isolated downwards; The sampling chamber triggering component is triggered by the upward-moving pressure-holding piston after sampling is completed, so as to interlock the triggering action of the pressure-holding chamber triggering component; The sampling chamber valve core assembly is used to close the sampling port after sampling is completed.

2. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 1, characterized in that, The first valve seat and the first valve cover are threaded together, and the first valve core is provided with an internal space for installing the first valve core. The first valve core includes a valve needle, a compression spring, a spring seat and a spring sleeve. The spring sleeve limits and fixes the spring seat, the compression spring and the valve needle from the upper side. The center of the spring sleeve is provided with a guide hole to guide and limit the upper end of the spring seat. The upper end of the spring seat is provided with a limiting guide rod. The lower part of the valve needle is sealed with the interface of the top liquid release branch. The internal space of the first valve core is connected to the first top liquid channel. The first valve cover is also provided with a top liquid channel connected to the top liquid upper pipe.

3. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 1, characterized in that, The second valve stem corresponding to the lower chamber has a reduced diameter section. The reduced diameter section extends downward to the lower end of the stem. When the second valve stem is triggered to move upward, the reduced diameter section moves upward to the upper side of the upper chamber to realize the connection between the upper chamber and the lower chamber, so as to connect the high-pressure nitrogen upper branch. The second valve seat has a high-pressure nitrogen lower branch that communicates with the lower chamber and extends downward to the lower side of the second valve seat.

4. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 1, characterized in that, The pressure-holding trigger assembly includes a trigger plug, a sliding sleeve support ring, a sliding sleeve, and a sliding sleeve trigger body. The outer circumference of the pressure-holding trigger assembly is provided with an outer sleeve. The upper part of the outer sleeve is threadedly sealed to the lower outer circumference of the second valve seat, and the upper inner circumference of the outer sleeve is threadedly connected to the sliding sleeve support ring. An outer support spring is provided on the middle outer circumference of the sliding sleeve support ring, supporting the upper end of the sliding sleeve and the middle of the sliding sleeve support ring. An inner convex guide ring is provided on the upper inner circumference of the sliding sleeve, which axially slides with the outer circumference of the sliding sleeve support ring. A limiting stop ring is provided on the lower outer circumference of the sliding sleeve support ring for axially limiting the inner convex guide ring. A guide rod section is provided at the lower part of the trigger plug. The guide rod section is axially slidingly engaged with the sliding sleeve support ring. The sliding sleeve support ring on the upper side of the limiting ring is provided with several steel ball holes in the circumference. The guide rod section is provided with several recesses in the circumference corresponding to the steel ball holes. The steel ball holes and recesses are matched one-to-one and fitted with steel balls. The steel balls are used to limit the axial movement of the trigger plug. An inner support spring is provided between the guide rod section on the upper side of the recess and the sliding sleeve support ring for abutting the trigger plug. The upper part of the trigger plug and the sliding sleeve support ring is provided with a guide section for axial sliding engagement. The sliding sleeve trigger body is fixed to the lower part of the sliding sleeve. The pressure holding chamber trigger assembly is provided with a fitting gap and channel to facilitate the connection of top liquid or high-pressure nitrogen. The upper side of the trigger plug is provided with a push rod that abuts against the second valve stem, and the lower end of the second valve seat is provided with a sealing mating part that seals with the trigger plug. The trigger plug abuts against the second valve stem. The upper side of the sealing mating part between the second valve seat and the trigger plug is provided with a top liquid chamber that communicates with the fourth top liquid channel. When sampling is completed, the sliding sleeve trigger body is unlocked by the upward triggering steel ball, the trigger plug moves up and simultaneously pushes the second valve stem to move up to connect the upper chamber and the lower chamber so that the high-pressure nitrogen upper branch is connected to the high-pressure nitrogen lower branch, while sealing and isolating the downward top liquid channel.

5. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 4, characterized in that, The sampling chamber includes a main sampling chamber tubular column. The upper part of the main sampling chamber tubular column is connected to the lower part of the outer sleeve with a circumferential threaded seal. The pressure-holding piston is fitted inside the main sampling chamber tubular column. A sampling chamber pull rod is slidably mounted at the center of the pressure-holding piston. The upper end of the sampling chamber pull rod is connected to the sampling chamber triggering component. The sampling inlet is located on the lower side wall of the main sampling chamber tubular column. The pressure-holding piston is located above the sampling inlet. The pressure-holding chamber is located inside the main sampling chamber tubular column above the pressure-holding piston. When the pressure-holding piston is pushed upward by the formation fluid to contact and trigger the sampling chamber triggering component, the sampling chamber triggering component and the pressure-holding chamber triggering component are triggered in conjunction to isolate the top fluid downward and connect high-pressure nitrogen to the pressure-holding chamber to achieve pressure holding in the sampling chamber.

6. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 5, characterized in that, The sampling chamber triggering assembly is located on the upper part of the main tube of the sampling chamber and includes a trigger rod, a trigger slide, a trigger sleeve, a trigger spring, and a trigger nut. The trigger rod passes through the central hole of the trigger slide. The lower outer circumference of the trigger slide is axially slidably sleeved with the upper inner circumference of the trigger sleeve. The trigger slide corresponding to the sliding section is provided with a limiting hole and a limiting steel ball around its circumference. The corresponding circumference of the trigger rod is provided with a limiting recess. The trigger nut is threadedly connected to the lower part of the trigger sleeve. A trigger spring is provided between the lower part of the trigger rod and the trigger nut. The trigger nut can be triggered by the upward-moving pressure-holding piston, which pushes the trigger rod upward.

7. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 5, characterized in that, The sampling chamber valve core assembly is located at the lower part of the sampling chamber main tube column, including a sampling valve core located below the pressure-holding piston. The upper center of the sampling valve core is threadedly connected to the sampling chamber pull rod. A sealing ring is fixed to the inner wall of the sampling chamber main tube column below the sampling inlet. The inner diameter of the sampling chamber main tube column below the sampling inlet is expanded outward so that the inner diameter of the ring after the sealing ring is installed is the same as the inner diameter of the sampling chamber main tube column above the sampling inlet. The upper outer circumference of the sampling valve core is provided with one or more sealing grooves for installing the sealing ring. The sealing groove is fitted with a sealing ring and a retaining ring. The middle and lower outer circumference of the sampling valve core is provided with a variable diameter outer step to facilitate the sliding fit between the lower part of the sampling valve core and the inner diameter expansion section of the lower part of the sampling chamber main tube column. After the sampling valve core is pulled upward by the sampling chamber pull rod, the part corresponding to the sealing groove moves from the position corresponding to the sealing ring to the upper side of the sampling inlet to seal the sampling inlet and end the sampling.

8. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 7, characterized in that, The sampling valve core has a limiting locking hole in the horizontal direction perpendicular to the central axis. The limiting locking hole radially penetrates the sampling valve core. A limiting spring is pressed into the limiting pressure block at both ends of the limiting locking hole, which opens and closes in opposite directions. The sampling chamber main column has a limiting groove in the radial direction to limit the upper limit position of the sampling valve core. The locking end of the limiting pressure block is engaged with the limiting groove to limit the position of the sampling valve core.

9. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 7, characterized in that, The sampling valve core has a sample transfer interface at a horizontal position below the outer step of the variable diameter. The sample transfer interface is sealed by a plug. A discharge hole communicating with the sampling chamber is provided in the axial direction perpendicular to the sample transfer interface. A valve hole is provided on the lower side of the discharge hole. A sampling valve needle is connected to the valve hole by an internal thread. When the sampling valve core is pulled to the upper limit position by the sampling chamber pull rod, a sample transfer hole is provided on the side wall of the main tube column of the sampling chamber corresponding to the sample transfer interface.

10. The high-temperature and high-pressure downhole pressure-maintaining sampler according to claim 5, characterized in that, The sampling inlet is equipped with a filter screen; the lower end of the main tube of the sampling chamber is provided with a lower end that communicates with the formation.

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