An oil field downhole sampler with good sealing performance

Abstract

The invention relates to an oilfield downhole sampler with good sealing performance, comprising a shell, wherein the interior of the shell is divided into a power chamber, a second collection chamber, a sliding chamber and a first collection chamber by a first partition, a second partition and a third partition, wherein a transmission mechanism for providing power for collecting samples is arranged in the sliding chamber, wherein a second piston slides in a connecting hole to reduce the air pressure in the first collection chamber, and an external oilfield sample enters the first collection chamber, and a rubber ball is reset to prevent the oilfield sample in the first collection chamber from leaking out, wherein after the positions of the first feed pipe and the strip hole correspond, the external oilfield sample enters the second collection chamber, and after the position of the second feed pipe corresponds to the second feed hole, a control valve is adjusted to allow the oilfield sample to enter the third collection chamber, so that the oilfield downhole sampler can perform three oilfield sampling operations after going down the well once, thereby greatly improving the sampling efficiency and reducing the leakage of the oilfield sample.

Description

Technical Field

[0001] The invention relates to the technical field of downhole samplers, in particular to an oil field downhole sampler with good sealing performance. Background Art

[0002] As disclosed in the patent application with publication number CN103195418B, the downhole sampler solves the problem of distortion of formation samples during the sampling process. However, it is not possible to sample different depths of the oil field in one trip down the well, and multiple trips down the well are required, which consumes a lot of manpower and time, making the sampling efficiency low. In addition, the sampler is in the open state, which is prone to sample leakage. At the same time, the oil field contains a small amount of sediment, which is easy to damage the sampler when collecting oil field samples. Summary of the invention

[0003] The technical problems solved by this solution are:

[0004] (1) How to coordinate the transmission mechanism, the first sampling mechanism, the second sampling mechanism and the third sampling mechanism, so that the second piston slides in the connecting hole, the air pressure of the first collecting chamber is reduced, the external oilfield sample enters the first collecting chamber, the rubber ball is reset, and the oilfield sample in the first collecting chamber is prevented from leaking out. After the first feed pipe corresponds to the position of the strip hole, the external oilfield sample enters the second collecting chamber. After the position of the second feed pipe corresponds to the second feed hole, the control valve is adjusted to allow the oilfield sample to enter the third collecting chamber, so that the oilfield downhole sampler can perform three oilfield sampling operations after one downhole operation, which greatly improves the sampling efficiency and reduces the leakage of oilfield samples.

[0005] (2) How to set up a servo motor and a transmission mechanism, close the control valve when the third collection chamber is filled with enough oilfield samples, raise the housing back to the bottom surface from the third designated depth, and open the control valve through the reverse operation of the servo motor to facilitate pouring out the oilfield samples at the three designated depths in sequence, thereby avoiding the situation where the oilfield downhole sampler must be manually disassembled to collect the oilfield samples;

[0006] (3) How to set up a filter net to filter out the silt in the oil field samples to prevent it from affecting the subsequent detection of the oil field samples.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A downhole sampler for oil fields with good sealing performance, comprising a shell, the interior of the shell is divided into a power chamber, a second collection chamber, a sliding chamber and a first collection chamber by a first partition, a second partition and a third partition, a transmission mechanism for providing power for collecting samples is arranged in the sliding chamber, a strip hole is opened on the outer wall of one side of the shell, a first filter screen for filtering mud and sand is fixedly installed inside the strip hole, the transmission mechanism comprises a first sleeve fixedly connected to the top of the third partition, and the internal movable sleeve of the first sleeve is provided with a screw A threaded rod, wherein a first thread segment and a second thread segment are formed on the threaded rod, a mounting bracket is threadedly connected to the first thread segment, a lifting tube is sleeved on the middle part of the threaded rod, the cross-section of the lifting tube is square, the lifting tube is fixedly connected to the inner wall of the lifting tube through the mounting bracket, a rubber sleeve is provided on the outer fixed sleeve of the lifting tube, a third sampling mechanism is provided on one side of the rubber sleeve, a first feeding tube is inserted on the other side of the rubber sleeve, the input end of the first feeding tube faces the shell and corresponds to the position of the strip hole, and a second sampling mechanism is provided in the second collecting chamber.

[0008] A further technical improvement of the present invention is that: the second sampling mechanism includes a second sleeve fixedly inserted on the second partition, a sealing ring is arranged at the top of the second sleeve, the bottom end of the second sleeve extends into the sliding cavity, a first piston is slidably arranged in the second collecting cavity, the top view of the first piston is square, a threaded sleeve is fixedly installed on the top of the first piston, the top end of the threaded screw movably passes through the second sleeve and the first piston, and is threadedly connected to the threaded sleeve through the second threaded section, the output end of the first feed pipe is connected to the second partition through a feed hose, a servo motor is fixedly installed in the power cavity, the output end of the servo motor movably passes through the first partition and is fixedly connected to the threaded screw; when the outer shell After descending to the second specified depth of the oil field, the servo motor rotates forward to drive the threaded screw to continue rotating, and cooperates with the threaded sleeve to drive the first piston to move upward, thereby reducing the pressure in the second collecting chamber below the first piston. When the position of the first feed pipe corresponds to the strip hole, the external oil field sample enters the second collecting chamber through the first feed pipe and the feed hose due to the external pressure, and the gas in the second collecting chamber above the first piston is discharged into the sliding chamber, thereby increasing the pressure in the first collecting chamber to prevent the external pressure from being too high, so that the external oil field sample enters the first collecting chamber again and affects the experimental sample. When a sufficient amount of oil field sample is collected in the second collecting chamber, the servo motor rotates forward to cause the rubber sleeve to block the strip hole.

[0009] A further technical improvement of the present invention is that a pressure-control hose for maintaining the atmospheric pressure in the shell is connected between the first piston and the second partition.

[0010] A further technical improvement of the present invention is that the cross sections of the power chamber, the second collecting chamber, the sliding chamber and the first collecting chamber are all rectangular.

[0011] A further technical improvement of the present invention is that a first sampling mechanism is arranged in the first collecting chamber, the first sampling mechanism includes a connecting hole opened on the third partition plate, a second piston is slidably arranged inside the connecting hole, a connecting rod is fixedly connected to the second piston, the length of the connecting rod is less than the distance between the first feeding pipe and the strip hole, the top end of the connecting rod passes through the connecting hole and is fixedly connected to the rubber sleeve, and an anti-backflow mechanism for preventing sample leakage is arranged on the outer shell below the third partition plate.

[0012] A further technical improvement of the present invention is that: the anti-backflow mechanism includes a first feed hole opened at the bottom of the shell, the interior of the first feed hole is wide at the top and narrow at the bottom, a rubber ball is clamped in the first feed hole, a second filter is fixedly installed at the bottom of the inner wall of the shell, and a thrust spring is elastically arranged between the second filter and the rubber ball; when the shell is lowered to the first specified depth of the oil field, the servo motor is driven to rotate by positive operation, the threaded screw remains stable under the limiting conditions of the first sleeve and the second sleeve, the threaded screw rotates to cooperate with the mounting frame to drive the lifting tube to move upward, so that the rubber sleeve moves upward to cooperate with the connecting rod to pull The second piston is moved to slide in the connecting hole, thereby reducing the air pressure in the first collecting chamber. When the external pressure exerts a thrust on the rubber ball greater than the thrust of the thrust spring, the thrust spring contracts, the rubber ball moves upward, and the external oil field sample enters the first collecting chamber through the first feed hole, and then the mud and sand in the oil field sample are filtered out through the second filter screen to prevent the subsequent detection of the oil field sample from being affected. When the second piston is disengaged from the connecting hole, the pressure in the first collecting chamber is slightly lower than the external pressure, the thrust spring is reset, and the rubber ball moves downward, so that the rubber ball blocks the first feed hole again to prevent the oil field sample in the first collecting chamber from leaking out.

[0013] A further technical improvement of the present invention is that: the third sampling mechanism includes a third collecting chamber opened inside the rubber sleeve, a mounting groove is opened on one side of the middle part of the rubber sleeve, a second feed pipe is arranged in the mounting groove, one end of the second feed pipe is communicated with the third collecting chamber, and a control valve is fixedly installed in the middle of the second feed pipe, a second feed hole is opened on the outer wall of the other side of the shell, a third filter screen is arranged inside the second feed hole, and the position of the second feed hole corresponds to the second feed pipe, and the distance between the second feed hole and the second feed pipe is greater than the distance between the first feed pipe and the bar The distance between the shaped holes; when the shell descends to the third designated depth of the oil field, the servo motor runs forward, so that the position of the second feed pipe corresponds to the second feed hole, and the control valve is opened, so that the oil field sample enters the third collecting chamber under the action of external pressure. When the third collecting chamber is filled with enough oil field samples, the control valve is closed, and the shell is raised from the third designated depth back to the bottom surface. The servo motor runs in the reverse direction to open the control valve, so that the oil field samples at the three designated depths can be poured out in turn, avoiding the situation where the oil field downhole sampler must be manually disassembled to collect the oil field samples.

[0014] A further technical improvement of the present invention is that a controller for controlling and adjusting the operation of the servo motor and the control valve is arranged on the first partition.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. When the present invention is in use, the servo motor is driven to rotate in the forward direction to drive the threaded screw to rotate, the lifting tube moves upward, and cooperates with the second piston to reduce the air pressure in the first collecting chamber. When the external pressure exerts a thrust on the rubber ball greater than the thrust of the thrust spring, the rubber ball moves upward, and the external oil field sample enters the first collecting chamber through the first feed hole. When the second piston is disengaged from the connecting hole, the pressure in the first collecting chamber is slightly less than the external pressure, the thrust spring is reset, and the rubber ball blocks the first feed hole again to prevent the oil field sample in the first collecting chamber from leaking out; the external oil field The sample enters the second collecting chamber due to the external pressure, and the gas in the second collecting chamber above the first piston is discharged into the sliding chamber, thereby increasing the pressure in the first collecting chamber to prevent the external pressure from being too high, causing the external oil field sample to enter the first collecting chamber again and affect the experimental sample; the position of the second feed pipe corresponds to the second feed hole, and the control valve is opened to allow the oil field sample to enter the third collecting chamber, so that the oil field downhole sampler can perform three oil field sampling operations after one downhole operation, which greatly improves the sampling efficiency and reduces the leakage of oil field samples.

[0017] 2. When the present invention is in use, after the third collecting chamber is filled with sufficient oilfield samples, the control valve is closed, the housing is raised from the third designated depth back to the bottom surface, and the servo motor is operated in reverse to open the control valve, so that the oilfield samples at the three designated depths can be poured out in turn, avoiding the situation where the oilfield downhole sampler must be manually disassembled to collect the oilfield samples.

[0018] 3. When the present invention is in use, the silt in the oil field sample is filtered out through the filter net to prevent the influence on the later detection of the oil field sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0020] Figure 1 It is a cross-sectional view of the overall structure of the present invention;

[0021] Figure 2 It is a three-dimensional schematic diagram of the overall external structure of the present invention;

[0022] Figure 3 It is a schematic diagram of the transmission mechanism structure of the present invention;

[0023] Figure 4 For the present invention Figure 3 Schematic diagram of the structure at A in the middle;

[0024] Figure 5 It is a three-dimensional schematic diagram of the threaded screw structure of the present invention;

[0025] Figure 6 It is a schematic diagram of the structure of the first sampling mechanism of the present invention;

[0026] Figure 7 For the present invention Figure 6 Schematic diagram of the structure at B in the middle;

[0027] Figure 8 It is a schematic diagram of the structure of the third sampling mechanism of the present invention.

[0028] In the figure: 1, power chamber; 2, first baffle; 3, second baffle; 4, second sleeve; 5, third sampling mechanism; 6, third baffle; 7, first sampling mechanism; 8, first collecting chamber; 9, first sleeve; 10, strip hole; 11, transmission mechanism; 12, sliding chamber; 13, shell; 14, second collecting chamber; 15, servo motor; 501, second feed hole; 502, second feed pipe; 503, third collecting chamber; 701, connecting rod; 702, second piston; 703, anti-backflow mechanism; 704, connecting hole; 1101, threaded screw; 1102, first piston; 1103, threaded sleeve; 1104, lifting tube; 1105, feed hose; 1106, rubber sleeve; 1107, mounting bracket; 1108, first feed pipe; 7031, thrust spring; 7032, first feed hole; 7033, rubber ball. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1 and Figure 2 As shown, a downhole sampler for oilfields with good sealing performance comprises a shell 13. The interior of the shell 13 is divided into a power chamber 1, a second collection chamber 14, a sliding chamber 12 and a first collection chamber 8 by a first partition plate 2, a second partition plate 3 and a third partition plate 6. The cross sections of the power chamber 1, the second collection chamber 14, the sliding chamber 12 and the first collection chamber 8 are all rectangular. A transmission mechanism 11 for providing power for collecting samples is arranged in the sliding chamber 12. A first sampling mechanism 7 is arranged in the first collection chamber 8. A strip hole 10 is opened on an outer wall of one side of the shell 13. A first filter screen for filtering sediment is fixedly installed inside the strip hole 10.

[0031] See also Figure 3 , Figure 4 and Figure 5As shown, the transmission mechanism 11 includes a first sleeve 9 fixedly connected to the top of the third partition plate 6, a threaded screw 1101 is movably sleeved inside the first sleeve 9, a first threaded section and a second threaded section are provided on the threaded screw 1101, a mounting bracket 1107 is threadedly connected to the first threaded section, a lifting tube 1104 is sleeved in the middle of the threaded screw 1101, the cross section of the lifting tube 1104 is square, the lifting tube 1104 is fixedly connected to the inner wall of the lifting tube 1104 through the mounting bracket 1107, a rubber sleeve 1106 is fixedly sleeved outside the lifting tube 1104, a third sampling mechanism 5 is provided on one side of the rubber sleeve 1106, a first feeding pipe 1108 is inserted on the other side of the rubber sleeve 1106, an input end of the first feeding pipe 1108 faces the outer shell 13 and corresponds to the position of the strip hole 10, and a second sampling mechanism for collecting oilfield samples is provided in the second collecting chamber 14.

[0032] See also Figure 3 As shown, the above-mentioned second sampling mechanism includes a second sleeve 4 fixedly inserted on the second partition 3, a sealing ring is provided at the top of the second sleeve 4, the bottom end of the second sleeve 4 extends into the sliding chamber 12, a first piston 1102 is slidably provided in the second collecting chamber 14, the top view of the first piston 1102 is square, a threaded sleeve 1103 is fixedly installed on the top of the first piston 1102, a pressure control hose for maintaining the atmospheric pressure in the shell 13 is connected between the first piston 1102 and the second partition 3, the top end of the threaded screw 1101 movably passes through the second sleeve 4 and the first piston 1102, and is threadedly connected to the threaded sleeve 1103 through the second threaded section, the output end of the first feed pipe 1108 is connected to the second partition 3 through the feed hose 1105, a servo motor 15 is fixedly installed in the power chamber 1, and the output end of the servo motor 15 movably passes through the first partition 2 and is fixedly connected to the threaded screw 1101; When the housing 13 descends to the second specified depth of the oil field, the servo motor 15 runs forward to drive the threaded screw 1101 to continue to rotate, and cooperates with the threaded sleeve 1103 to drive the first piston 1102 to move upward, thereby reducing the pressure in the second collecting chamber 14 below the first piston 1102. When the first feed pipe 1108 corresponds to the position of the strip hole 10, the external oil field sample enters the second collecting chamber 14 through the first feed pipe 1108 and the feed hose 1105 due to the action of the external pressure, and the gas in the second collecting chamber 14 above the first piston 1102 is discharged into the sliding chamber 12, thereby increasing the pressure in the first collecting chamber 8 to prevent the external pressure from being too high, so that the external oil field sample enters the first collecting chamber 8 again and affects the experimental sample. When a sufficient amount of oil field sample is collected in the second collecting chamber 14, the servo motor 15 runs forward to cause the rubber sleeve 1106 to block the strip hole 10.

[0033] See also Figure 6As shown, the above-mentioned first sampling mechanism 7 includes a connecting hole 704 opened on the third partition plate 6, a second piston 702 is slidably arranged inside the connecting hole 704, a connecting rod 701 is fixedly connected to the second piston 702, the length of the connecting rod 701 is less than the distance between the first feed pipe 1108 and the strip hole 10, the top end of the connecting rod 701 passes through the connecting hole 704 and is fixedly connected to the rubber sleeve 1106, and an anti-backflow mechanism 703 for preventing sample leakage is arranged on the outer shell 13 below the third partition plate 6.

[0034] See also Figure 7 As shown, the anti-backflow mechanism 703 includes a first feed hole 7032 opened at the bottom of the shell 13, the interior of the first feed hole 7032 is wide at the top and narrow at the bottom, a rubber ball 7033 is clamped in the first feed hole 7032, a second filter is fixedly installed at the bottom of the inner wall of the shell 13, and a thrust spring 7031 is elastically arranged between the second filter and the rubber ball 7033; when the shell 13 is lowered to the first specified depth of the oil field, the servo motor 15 is driven to rotate in the forward direction to drive the threaded screw 1101 to rotate, the threaded screw 1101 remains stable under the limiting conditions of the first sleeve 9 and the second sleeve 4, the threaded screw 1101 rotates to cooperate with the mounting frame 1107 to drive the lifting tube 1104 to move upward, so that the rubber sleeve 1106 moves upward to cooperate with the connecting rod 701 to pull the second The piston 702 slides in the connecting hole 704, thereby reducing the air pressure in the first collecting chamber 8. When the external pressure exerts a thrust on the rubber ball 7033 that is greater than the thrust of the thrust spring 7031, the thrust spring 7031 contracts, and the rubber ball 7033 moves upward. The external oil field sample enters the first collecting chamber 8 through the first feed hole 7032, and then the mud and sand in the oil field sample are filtered out through the second filter screen to prevent the subsequent detection of the oil field sample from being affected. When the second piston 702 is disengaged from the connecting hole 704, the pressure in the first collecting chamber 8 is slightly less than the external pressure, the thrust spring 7031 is reset, and the rubber ball 7033 moves downward, so that the rubber ball 7033 blocks the first feed hole 7032 again to prevent the oil field sample in the first collecting chamber 8 from leaking out.

[0035] See also Figure 8As shown, the third sampling mechanism 5 includes a third collecting chamber 503 opened inside the rubber sleeve 1106, a mounting groove is opened on one side of the middle of the rubber sleeve 1106, a second feed pipe 502 is arranged in the mounting groove, one end of the second feed pipe 502 is connected with the third collecting chamber 503, and a control valve is fixedly installed in the middle of the second feed pipe 502, a second feed hole 501 is opened on the outer wall of the other side of the shell 13, a third filter screen is arranged inside the second feed hole 501, and the position of the second feed hole 501 corresponds to the second feed pipe 502, and the distance between the second feed hole 501 and the second feed pipe 502 is greater than that of the first feed pipe 1108. The distance between the outer shell 13 and the strip hole 10; when the outer shell 13 descends to the third specified depth of the oil field, the servo motor 15 runs forward, so that the position of the second feed pipe 502 corresponds to the second feed hole 501, and the control valve is opened to allow the oil field sample to enter the third collecting chamber 503 under the action of external pressure. When the third collecting chamber 503 is filled with enough oil field samples, the control valve is closed, and the outer shell 13 is raised back to the bottom surface from the third specified depth. The servo motor 15 runs in the reverse direction to open the control valve, so that the oil field samples at the three specified depths can be poured out in turn, avoiding the situation where the oil field downhole sampler must be manually disassembled to collect the oil field samples.

[0036] See also Figure 1 As shown, the first partition plate 2 is provided with a controller for controlling and adjusting the servo motor 15 and the operation of the control valve.

[0037] Working principle: When the present invention is used, first, after the housing 13 descends to the first specified depth of the oil field, the servo motor 15 is driven to rotate in the forward direction to drive the threaded screw 1101 to rotate. The threaded screw 1101 remains stable under the limiting conditions of the first sleeve 9 and the second sleeve 4. The threaded screw 1101 rotates to cooperate with the mounting frame 1107 to drive the lifting tube 1104 to move upward, so that the rubber sleeve 1106 moves upward to cooperate with the connecting rod 701 to pull the second piston 702 to slide in the connecting hole 704, thereby reducing the air pressure in the first collecting chamber 8. When the thrust of the external pressure on the rubber ball 7033 is greater than the thrust of the thrust spring 7031, the thrust spring 7031 contracts and the rubber ball 7033 is pushed upward. 33 moves upward, and the external oilfield sample enters the first collecting chamber 8 through the first feed hole 7032, and then the sediment in the oilfield sample is filtered out through the second filter screen to prevent the subsequent detection of the oilfield sample from being affected. When the second piston 702 is disengaged from the connecting hole 704, the pressure in the first collecting chamber 8 is slightly less than the external pressure, the thrust spring 7031 is reset, and the rubber ball 7033 moves downward, so that the rubber ball 7033 blocks the first feed hole 7032 again to prevent the oilfield sample in the first collecting chamber 8 from leaking out; when the housing 13 descends to the second specified depth of the oilfield, the servo motor 15 runs forward to drive the threaded screw 1101 to continue to rotate, and the servo motor 15 drives the threaded screw 1101 to rotate. The threaded sleeve 1103 drives the first piston 1102 to move upward, reducing the pressure of the second collecting chamber 14 below the first piston 1102. When the first feeding pipe 1108 corresponds to the position of the strip hole 10, the external oil field sample enters the second collecting chamber 14 through the first feeding pipe 1108 and the feeding hose 1105 due to the external pressure, and the gas in the second collecting chamber 14 above the first piston 1102 is discharged into the sliding chamber 12, thereby increasing the pressure in the first collecting chamber 8 to prevent the external pressure from being too high, so that the external oil field sample enters the first collecting chamber 8 again and affects the experimental sample. When a sufficient amount of oil field sample is collected in the second collecting chamber 14, the servo motor 15 runs forward so that the rubber sleeve 1106 blocks the strip hole 10; when the housing 13 descends to the third designated depth of the oil field, the servo motor 15 runs forward so that the position of the second feed pipe 502 corresponds to the second feed hole 501, and the control valve is opened to allow the oil field sample to enter the third collecting chamber 503 under the action of external pressure. When the third collecting chamber 503 is filled with enough oil field samples, the control valve is closed, and the housing 13 is raised from the third designated depth back to the bottom surface. The servo motor 15 runs in the reverse direction to open the control valve, so that the oil field samples at the three designated depths can be dumped out in turn, avoiding the situation where the oil field downhole sampler must be manually disassembled to collect the oil field samples.

[0038] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0039] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An oilfield downhole sampler with good sealing performance, comprising a housing (13), characterized in that: The interior of the housing (13) is divided into a power chamber (1), a second collection chamber (14), a sliding chamber (12) and a first collection chamber (8) by a first partition (2), a second partition (3) and a third partition (6); a transmission mechanism (11) is arranged in the sliding chamber (12); a strip hole (10) is opened on an outer wall of one side of the housing (13); a first filter screen for filtering sediment is fixedly installed inside the strip hole (10); the transmission mechanism (11) comprises a first sleeve (9) fixedly connected to the top of the third partition (6); a threaded sleeve is provided inside the first sleeve (9) a screw rod (1101), wherein a first threaded section and a second threaded section are formed on the threaded screw rod (1101), a lifting tube (1104) is threadedly connected to the first threaded section, a rubber sleeve (1106) is provided on the external fixing sleeve of the lifting tube (1104), a third sampling mechanism (5) is provided on one side of the rubber sleeve (1106), a first feeding tube (1108) is inserted on the other side of the rubber sleeve (1106), an input end of the first feeding tube (1108) corresponds to the position of the strip-shaped hole (10), and a second sampling mechanism is provided in the second collecting chamber (14); The second sampling mechanism comprises a second sleeve (4) fixedly inserted on the second partition (3), a sealing ring is arranged at the top end of the second sleeve (4), the bottom end of the second sleeve (4) extends into the sliding chamber (12), a first piston (1102) is slidably arranged in the second collecting chamber (14), a threaded sleeve (1103) is fixedly installed on the top of the first piston (1102), the top end of the threaded screw (1101) movably penetrates the second sleeve (4) and the first piston (1102), and is threadedly connected to the threaded sleeve (1103) through a second threaded section, the output end of the first feed pipe (1108) is connected to the second partition (3) through a feed hose (1105), and a servo motor (15) is fixedly installed in the power chamber (1), the output end of the servo motor (15) movably penetrates the first partition (2) and is fixedly connected to the threaded screw (1101); A first sampling mechanism (7) is arranged in the first collecting chamber (8), the first sampling mechanism (7) comprises a connecting hole (704) opened on the third partition plate (6), a second piston (702) is slidably arranged inside the connecting hole (704), the second piston (702) is fixedly connected to the rubber sleeve (1106) via a connecting rod (701), and a backflow prevention mechanism (703) for preventing sample leakage is arranged on the housing (13) below the third partition plate (6); The third sampling mechanism (5) comprises a third collecting chamber (503) provided inside the rubber sleeve (1106); a mounting groove is provided on one side of the middle of the rubber sleeve (1106); a second feed pipe (502) is provided in the mounting groove; one end of the second feed pipe (502) is communicated with the third collecting chamber (503); a control valve is fixedly installed in the middle of the second feed pipe (502); a second feed hole (501) is provided on the outer wall of the other side of the housing (13); the position of the second feed hole (501) corresponds to that of the second feed pipe (502); The anti-backflow mechanism (703) comprises a first feed hole (7032) provided at the bottom of the housing (13), a rubber ball (7033) being clamped in the first feed hole (7032), a second filter screen being fixedly mounted on the bottom of the inner wall of the housing (13), and a thrust spring (7031) being elastically arranged between the second filter screen and the rubber ball (7033); When the housing (13) descends to the first designated depth of the oil field, the servo motor (15) is driven to rotate by the forward rotation of the threaded screw (1101). The threaded screw (1101) remains stable under the limiting conditions of the first sleeve (9) and the second sleeve (4). The threaded screw (1101) rotates to cooperate with the mounting frame (1107) to drive the lifting tube (1104) to move upward, so that the rubber sleeve (1106) moves upward to cooperate with the connecting rod (701) to pull the second piston (702) to slide in the connecting hole (704), thereby reducing the air pressure in the first collecting chamber (8). When the external pressure exerts a thrust on the rubber ball (7033) greater than the thrust of the thrust spring (7031), the thrust spring (7031) contracts and the rubber ball (7033) is pushed upward. 033) moves upward, and the external oilfield sample enters the first collecting chamber (8) through the first feed hole (7032), and then the sediment in the oilfield sample is filtered out through the second filter screen to prevent the subsequent detection of the oilfield sample from being affected. When the second piston (702) is disengaged from the connecting hole (704), the pressure in the first collecting chamber (8) is slightly lower than the external pressure, the thrust spring (7031) is reset, and the rubber ball (7033) moves downward, so that the rubber ball (7033) blocks the first feed hole (7032) again to prevent the oilfield sample in the first collecting chamber (8) from leaking out; when the housing (13) descends to the second specified depth of the oilfield, the servo motor (15) rotates forward to drive the threaded screw (1 101) continues to rotate, and cooperates with the threaded sleeve (1103) to drive the first piston (1102) to move upward, thereby reducing the pressure of the second collection chamber (14) below the first piston (1102). When the first feed pipe (1108) corresponds to the position of the strip hole (10), the external oil field sample enters the second collection chamber (14) through the first feed pipe (1108) and the feed hose (1105) due to the action of the external pressure, and the gas in the second collection chamber (14) above the first piston (1102) is discharged into the sliding chamber (12), thereby increasing the pressure in the first collection chamber (8) to prevent the external pressure from being too high, so that the external oil field sample enters the first collection chamber (8) again and affects the experimental sample. After a sufficient amount of oilfield samples are collected in the collection chamber (14), the servo motor (15) rotates in the forward direction so that the rubber sleeve (1106) blocks the strip hole (10); when the housing (13) descends to a third designated depth of the oilfield, the servo motor (15) rotates in the forward direction so that the position of the second feed pipe (502) corresponds to the second feed hole (501), and the control valve is opened so that the oilfield samples enter the third collection chamber (503) under the action of external pressure; when the third collection chamber (503) is filled with sufficient oilfield samples, the control valve is closed, and the housing (13) is raised from the third designated depth back to the bottom surface, and the servo motor (15) rotates in the reverse direction to cooperate with the opening of the control valve, so that the oilfield samples at the three designated depths can be poured out in sequence.

2. The oilfield downhole sampler with good sealing performance according to claim 1, characterized in that: A pressure-control hose for maintaining the atmospheric pressure in the housing (13) is connected between the first piston (1102) and the second partition plate (3).

3. The oilfield downhole sampler with good sealing performance according to claim 1, characterized in that: The cross-sections of the power chamber (1), the second collecting chamber (14), the sliding chamber (12) and the first collecting chamber (8) are all rectangular.

4. The oilfield downhole sampler with good sealing performance according to claim 1, characterized in that: The first partition plate (2) is provided with a controller for controlling and adjusting the operation of the servo motor (15) and the control valve.

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