Downhole crawler hydraulic circuit system and downhole crawler

Abstract

The present application relates to a kind of downhole crawler hydraulic circuit system and downhole crawler, hydraulic circuit system includes hydraulic pump and hydraulic oil cavity, hydraulic oil cavity is provided with the push piston that first cavity and second cavity are divided by it, the oil outlet of hydraulic pump is connected with first cavity by one-way valve, one-way valve is set to the hydraulic oil pumped by hydraulic pump flows into first cavity by it, the inlet of first reversing valve is connected with the pipeline between one-way valve and first cavity, the outlet of first reversing valve and second cavity are all connected with oil tank, first reversing valve is set to the normally open state that can make the hydraulic oil in first cavity flow back to oil tank by it in normal state, the end of the piston rod of push piston that extends outside second cavity is used to be connected with the crawling arm of downhole crawler, recovery spring is provided in second cavity, to make crawling arm can be retracted.The present application overcomes the defects of existing hydraulic system, can well meet the increasingly stringent downhole use environment requirements.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development technology, specifically relating to a downhole crawler hydraulic circuit system and a downhole crawler. Background Technology

[0002] With the rapid development of the social economy, the demand for oil from all sectors is increasing daily. As oilfield development deepens, the transition from shallow to deep formations and from vertical wells to horizontal wells has become an inevitable trend. Horizontal well production is a crucial technology for enhancing oil and gas recovery. With the continuous development of horizontal well drilling technology, the total number of horizontal wells is rapidly increasing. Furthermore, during deep oil extraction, downhole malfunctions of varying degrees are inevitable, requiring well workover and testing to ensure normal oil and gas production. Logging instruments and workover tools are primarily delivered via downhole crawlers.

[0003] Downhole crawlers can facilitate the transport of various instruments in horizontal wells, such as logging instruments, and other auxiliary operations, including perforation, fishing, plugging, sampling, well descaling, and valve operation. This solves the problem of transporting downhole instruments or equipment to predetermined locations in highly deviated or horizontal wells by gravity. Compared to traditional methods of instrument transport in horizontal wells, downhole crawlers do not require large equipment and occupy less space. During the lifting and lowering process, the speed and position are controllable, preventing damage to logging instruments. Furthermore, downhole crawlers can precisely travel along the well wall in confined spaces containing multiple media in high-pressure wells. They offer advantages such as short length, light weight, convenient transportation, simple operation, and the ability to deliver downhole instruments to accurate locations, significantly reducing the cost of downhole operations such as logging.

[0004] However, the following technical problems still exist when the downhole crawler is used in the field: the existing crawler hydraulic circuit system often fails to operate due to the crawler arm being loose, the crawler arm being unable to retract, and the pressure imbalance inside and outside the instrument; in addition, when the oil inside the crawler becomes dirty due to repeated use and contains small impurities, and the hydraulic motor, hydraulic pump, and solenoid directional valve stop working, the return oil port is prone to blockage, which makes it impossible for the crawler arm to retract completely, and jamming may occur during the lifting process, causing significant losses.

[0005] Therefore, it is particularly important to design a safe and reliable hydraulic circuit system. Summary of the Invention

[0006] To address all or part of the aforementioned problems, the present invention aims to provide a downhole crawler hydraulic circuit system and a downhole crawler. The downhole crawler hydraulic circuit system of the present invention overcomes the defects of existing hydraulic systems, can well meet the increasingly stringent requirements of downhole operating environments, and realizes the pushing and retrieval of the crawler arm and the automatic recovery of the crawler arm when the instrument loses power.

[0007] According to one aspect of the present invention, a hydraulic circuit system for a downhole crawler is provided, comprising a hydraulic pump, a hydraulic oil chamber, and a first directional valve. The hydraulic oil chamber is provided with a push piston that divides the hydraulic oil chamber into a first chamber and a second chamber. The outlet of the hydraulic pump is connected to the first chamber via a check valve, which is configured to allow hydraulic oil pumped by the hydraulic pump to flow into the first chamber. The inlet of the first directional valve is connected to a pipeline between the check valve and the first chamber. The outlet of the first directional valve and the second chamber are both connected to an oil tank. Under normal conditions, the first directional valve is configured to be normally open, allowing hydraulic oil in the first chamber to flow back to the oil tank. One end of the piston rod of the push piston extends out of the second chamber and is used to connect to the crawler arm of the downhole crawler. A retraction spring is provided in the second chamber, which, when the first directional valve is in the normally open state, drives the push piston to compress the first chamber, thereby retracting the crawler arm.

[0008] Furthermore, a filter is provided between the oil outlet of the hydraulic pump and the check valve, a pressure sensor is provided between the check valve and the first cavity, and a first relief valve is provided between the first cavity and the oil tank.

[0009] Furthermore, the hydraulic pump is connected to a hydraulic motor, which drives the hydraulic pump to operate.

[0010] Furthermore, the hydraulic circuit system also includes a pressure stabilizing system, which is used to stabilize the pressure in the first cavity so that the crawler arm is in a stable pushing state.

[0011] Furthermore, the pressure stabilizing system includes a pressure stabilizing chamber, in which an energy storage piston is disposed. The energy storage piston divides the pressure stabilizing chamber into a third chamber and a fourth chamber. The third chamber is connected to the pipeline between the one-way valve and the first chamber. An energy storage spring is disposed in the fourth chamber. The energy storage spring is configured to be gradually compressed after the hydraulic oil enters the third chamber, so that when the pressure in the first chamber decreases, it drives the energy storage piston to squeeze the third chamber, thereby stabilizing the pressure in the first chamber.

[0012] Furthermore, the hydraulic circuit system also includes a balancing system for balancing the pressure between the oil tank, the first cavity, the second cavity, the fourth cavity, and the leaking oil tank.

[0013] Furthermore, the balancing system includes a balancing chamber, in which a balancing piston is disposed. The balancing piston divides the balancing chamber into a fifth chamber and a sixth chamber. The fifth chamber is connected to the fourth chamber. A balancing spring is disposed in the fifth chamber. The sixth chamber is connected to the leaking oil tank.

[0014] Furthermore, the pipeline between the fifth cavity and the fourth cavity is connected to one end of the pressure relief valve and the inlet of the second overflow valve, and the other end of the pressure relief valve and the outlet of the second overflow valve are both connected to the leakage oil tank, and the oil tank is connected to one end of the pressure relief valve.

[0015] Furthermore, the hydraulic circuit system also includes a second directional valve, the inlet of which is connected to the pipeline between the check valve and the first cavity, and the outlet of which is connected to the oil tank. Under normal conditions, the second directional valve is configured to be in a normally closed state, preventing the hydraulic oil in the first cavity from flowing back to the oil tank.

[0016] Furthermore, the hydraulic circuit system also includes a third directional valve, the inlet of which is connected to the pipeline between the check valve and the hydraulic pump, and the outlet of which is connected to the oil tank. Under normal conditions, the third directional valve is configured to be in a normally open state that allows the hydraulic oil between the check valve and the hydraulic pump to flow back to the oil tank.

[0017] This invention also provides a downhole crawler, which is equipped with the downhole crawler hydraulic circuit system described in any one of the above embodiments.

[0018] As can be seen from the above technical solution, the hydraulic circuit system and downhole crawler provided by the present invention have the following beneficial effects: The hydraulic circuit system of the downhole crawler of the present invention overcomes the defects of the existing hydraulic system and can well meet the increasingly stringent requirements of the downhole operating environment. The downhole crawler with the hydraulic circuit system can produce a more ideal crawling effect. The hydraulic circuit system of the downhole crawler of the present invention controls the connection between the hydraulic pump and the first chamber through a first reversing valve and a check valve, thereby realizing the pushing of the crawler arm; the first reversing valve controls the connection between the first chamber and the oil tank, and in conjunction with the compressed recovery spring, pushes the piston, allowing hydraulic oil to flow from the first chamber back to the oil tank, thereby realizing the recovery of the crawler arm; the normally open design of the recovery spring and the first reversing valve of the present invention achieves the purpose of automatically recovering the crawler arm when the instrument is powered off. This invention, through the redundant setting of the second directional valve, enables the retraction of the crawler arm when the return oil filter of the first directional valve is blocked by impurities in the hydraulic oil, thus avoiding well jamming accidents and achieving the purpose of safety protection. The present invention ensures stable pressure in the first chamber by setting up a pressure stabilization system, which ensures that the traction force output by the crawler remains constant, so that the crawling arm is always in a stable pushing state, thereby improving the crawling effect and increasing the success rate of operation. The balance piston in this invention plays a role in balancing the pressure inside and outside the instrument, keeping the pressure difference between the inside and outside of the instrument within a reasonable range to ensure the normal operation of the crawler. This invention achieves accurate adjustment of the pushing force of the crawler arm by setting up a first reversing valve and a third reversing valve. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the hydraulic circuit system of the downhole crawler according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of the hydraulic system of the downhole crawler hydraulic circuit system according to an embodiment of the present invention; Figure 3 This is a cross-sectional view of the pressure stabilization system and the balancing system of the hydraulic circuit system of the downhole crawler according to an embodiment of the present invention; Figure 4 for Figure 3 Sectional view along the BB direction. Detailed Implementation

[0020] To better understand the purpose, structure, and function of this invention, the following detailed description of a downhole crawler hydraulic circuit system and a downhole crawler, in conjunction with the accompanying drawings, is provided.

[0021] like Figure 1 , Figure 2The diagram illustrates a hydraulic circuit system for a downhole crawler according to an embodiment of the present invention, including a hydraulic pump 3, a hydraulic oil chamber 11, and a first directional valve 7. The hydraulic oil chamber 11 is equipped with a push piston that divides it into a first chamber 111 and a second chamber 112. The outlet of the hydraulic pump 3 is connected to the first chamber 111 via a check valve 6. The check valve 6 is configured to allow hydraulic oil pumped by the hydraulic pump 3 to flow into the first chamber 111. The inlet of the first directional valve 7 is located between the check valve 6 and the first chamber 111. The pipeline connection is such that the outlet of the first directional valve 7 and the second chamber 112 are both connected to the oil tank. Under normal conditions, the first directional valve 7 is set to be in a normally open state that allows the hydraulic oil in the first chamber 111 to flow back to the oil tank through it. The piston rod of the push piston extends out of the second chamber 112 and is used to connect to the crawler arm of the downhole crawler. A retraction spring is provided in the second chamber 112. The retraction spring is used to drive the push piston to squeeze the first chamber 111 to move when the first directional valve 7 is in the normally open state, so that the crawler arm can be retracted.

[0022] Specifically, the hydraulic circuit system of the downhole crawler in this embodiment of the invention includes a hydraulic system formed by a hydraulic pump 3, a hydraulic oil chamber 11, a first directional valve 7, and a check valve 6. This hydraulic system is used to control the extension and retraction of the crawler arm of the downhole crawler. Specifically, the check valve 6 and the first directional valve 7 are used to control the connection state between the hydraulic pump 3 and the hydraulic oil chamber 11. When the crawler is powered off, the first directional valve 7 is in the normally open state. At this time, the first chamber 111 is connected to the oil tank through the first directional valve 7, and the second chamber 112 is connected to the oil tank. At this time, the push piston is in the initial state under the action of the retraction spring, and the crawler arm is in the retracted state. When the crawler is working, the first directional valve switches to the closed state that prevents hydraulic oil from flowing through, and the hydraulic motor is started. The hydraulic motor drives the hydraulic pump 3 to pump hydraulic oil from the oil chamber through the check valve 6 into the first chamber 111 of the hydraulic oil chamber 11. The pressure inside chamber 111 rises to form a high-pressure chamber. The hydraulic pressure in this high-pressure chamber pushes the push piston to move. The movement of the push piston begins to compress the retraction spring, gradually increasing the compression of the retraction spring. At the same time, the movement of the push piston pushes the crawler arm against the inner wall of the pipe, realizing the hydraulic push function of the crawler. When the crawler stops working, the first reversing valve switches to the normally open state. At this time, the hydraulic oil in the first chamber 111 flows back to the oil tank through the first reversing valve 7. Under the elastic potential energy stored in its own body, the retraction spring pushes the push piston to move in the direction that reduces the volume of the first chamber 111. The movement of the push piston in this direction realizes the retraction of the crawler arm.

[0023] Regarding the process of the crawler arm pushing against the inner wall of the pipe, when the hydraulic oil pressure in the first chamber 111 is too high, the hydraulic oil pressure in the first chamber 111 can be finely adjusted and reduced through the first reversing valve 7. Specifically, the first reversing valve 7 can be switched from a closed state that prevents hydraulic oil from flowing through to a normally open state that allows hydraulic oil in the first chamber 111 to flow through. At this time, part of the hydraulic oil in the first chamber 111 flows back to the oil tank through the first reversing valve 7.

[0024] In the hydraulic circuit system of the downhole crawler according to this embodiment of the invention, the communication state between the hydraulic pump and the first chamber is controlled by a first directional valve and a check valve, thereby achieving the pushing of the crawler arm; the communication state between the first chamber and the oil tank is controlled by the first directional valve, and in conjunction with the compressed recovery spring pushing the push piston, the hydraulic oil can flow from the first chamber back to the oil tank, thus achieving the recovery of the crawler arm. Furthermore, the normally open design of the recovery spring and the first directional valve enables automatic recovery of the crawler arm when the instrument is powered off.

[0025] A filter 4 is installed between the oil outlet of the hydraulic pump 3 and the check valve 6. The filter 4 is used to perform preliminary filtration of the hydraulic oil. A pressure sensor 10 is installed between the check valve 6 and the first chamber 111. The pressure sensor is used to monitor the pressure of the relevant oil circuit in real time. A first relief valve 5 is also installed between the first chamber 111 and the oil tank. The first relief valve 5 plays a safety protection role in stabilizing pressure and overflowing.

[0026] The hydraulic pump 3 is connected to the hydraulic motor 2, which drives the hydraulic pump 3 to work.

[0027] The hydraulic circuit system also includes a second directional valve 8. The inlet of the second directional valve 8 is connected to the pipeline between the check valve 6 and the first chamber 111, and the outlet of the second directional valve 8 is connected to the oil tank. Under normal conditions, the second directional valve 8 is set to a normally closed state that prevents the hydraulic oil in the first chamber 111 from flowing back to the oil tank.

[0028] In this embodiment of the invention, the setting of the first reversing valve and the second reversing valve achieves the purpose of safety redundancy protection. Specifically, the second reversing valve is normally set to a normally closed state that prevents the hydraulic oil in the first chamber 111 from flowing back to the oil tank. When the downhole crawler is working normally, the second reversing valve 8 is always in the aforementioned normally closed state. In this case, the connection between the first chamber 111 and the oil tank is controlled only by the first reversing valve. However, as the instrument is used for a long time, the internal oil gradually becomes dirty and impurities appear. Therefore, when the return oil filter of the first solenoid valve is blocked by impurities in the oil, causing the crawler arm to be unable to retract, the connection between the first chamber 111 and the oil tank can be realized through the spare second reversing valve. At this time, the second reversing valve is switched to the open state, and the hydraulic oil in the first chamber 111 flows back to the oil chamber through the second reversing valve, completing the retrieval of the crawler arm.

[0029] This invention, through the provision of a second directional valve, effectively prevents impurities in the hydraulic oil from clogging the return oil filter of the first solenoid valve after long-term use, thus avoiding a stuck situation where the crawler arm cannot fully retract. Furthermore, the second directional valve is a normally closed valve, ensuring it is idle during normal operation. Therefore, impurities in the hydraulic oil will not simultaneously clog the return oil filters of both the first solenoid valve and the second directional valve. When the return oil filter of the first directional valve is clogged by impurities in the hydraulic oil, preventing pressure release and thus hindering the crawler arm's retraction, the second directional valve is opened to connect the first chamber 111 to the oil tank. This allows the hydraulic oil in the first chamber 111 to flow back into the oil tank, enabling the crawler arm to return to its initial position, preventing a stuck well accident and achieving safety protection.

[0030] The cross-sectional views of the hydraulic motor 2, hydraulic pump 3, filter 4, first relief valve 5, check valve 6, pressure sensor 10, first directional valve 7, and second directional valve 8 in this embodiment of the invention are as follows: Figure 2 As shown, Figure 2 As shown, the hydraulic circuit system of the downhole crawler in this embodiment of the invention also includes a housing 1 and a valve seat 9. The housing 1 is positioned relative to the upper connector by four limiting pins and is fastened to the upper connector by four circumferential screws. The hydraulic motor 2 is fastened to the upper connector by four circumferential screws. The hydraulic pump 3 is connected to the hydraulic motor 2 by three circumferential nuts. The filter 4 is disposed in the filter mounting bracket 41, which is threadedly connected to the hydraulic pump 3. The overflow valve 5 and the check valve 6 are both fastened to the valve seat 9. The first directional valve 7 is pressed and fixed to the valve seat 9 by the filter mounting bracket. The second directional valve 8 is pressed and fixed to the valve seat 9 by the pressure cap. The left side of the valve seat 9 is connected to the filter mounting bracket by screws, and the right side of the valve seat 9 is connected to the pressure cap by screws. The pressure sensor 10 is threadedly connected to the valve seat 9.

[0031] The hydraulic circuit system of this embodiment of the invention further includes a pressure stabilizing system, which is used to stabilize the pressure in the first cavity 111 so that the crawler arm is in a stable pushing state.

[0032] Specifically, such as Figure 1 , Figure 3 , Figure 4As shown, the pressure stabilizing system includes a pressure stabilizing chamber, in which an energy storage piston 12 is installed. The energy storage piston 12 divides the pressure stabilizing chamber into a third chamber 121 and a fourth chamber 122. The third chamber 121 is connected to the pipeline between the one-way valve 6 and the first chamber 111. An energy storage spring is installed in the fourth chamber 122. The energy storage spring is configured to be gradually compressed after the hydraulic oil enters the third chamber 121, so that when the pressure in the first chamber 111 decreases, it drives the energy storage piston 12 to squeeze the third chamber 121, so that the pressure in the first chamber 111 is stabilized.

[0033] In the pressure stabilizing system of this embodiment, the energy storage piston is used to maintain the pressure stability of the first chamber 111 during the process of the crawler arm being pushed against the inner wall of the pipe. Specifically, when the hydraulic pump 3 is working, a portion of hydraulic oil is pumped into the third chamber. As the oil is continuously pumped, the oil pressure in the third chamber continues to rise, causing the energy storage piston 12 to move in the direction of compressing the energy storage spring. The energy storage spring is compressed and converts the hydraulic kinetic energy into elastic potential energy. When the set pressure is reached inside the first chamber 111, the hydraulic pump stops working. As the downhole temperature and pressure change, the pressure inside the first chamber 111 fluctuates. When the pressure inside the first chamber 111 decreases, the energy storage spring converts its elastic potential energy into kinetic energy, pushing the energy storage piston 12 to move in the direction of squeezing the third chamber 121. At this time, the hydraulic oil in the third chamber is squeezed out and flows into the first chamber 111, thus keeping the pressure inside the first chamber 111 stable. Conversely, when the pressure inside the first chamber 111 increases, some hydraulic oil flows out of the first chamber 111 and into the third chamber. This portion of hydraulic oil is converted into potential energy by compressing the energy storage spring. The third chamber is connected to the first chamber 111 and the first relief valve 5 via pipelines.

[0034] The design of the pressure stabilization system in this embodiment of the invention ensures that the pressure in the first cavity 111 is stable, and ensures that the traction force output by the crawler remains constant, so that the crawling arm is always in a stable pushing state, thereby improving the crawling effect and increasing the success rate of the operation.

[0035] Regarding the design of the pressure stabilizing system in this embodiment of the invention: by setting an energy storage spring and an energy storage piston 12 in the hydraulic circuit system, energy storage can be achieved during the hydraulic pump's pumping state, and the circuit pressure can be replenished in a timely manner after the hydraulic pump stops pumping, so as to maintain the pressure stability in the first chamber 111, so that the crawler arm's pushing force remains constant, and thus ensures that the output drag force remains constant. Compared with the prior art, the setting of this embodiment of the invention is more advanced and innovative, and can provide a more stable pushing force.

[0036] The hydraulic circuit system also includes a balancing system, which is used to balance the pressure between the oil tank, the first chamber, the second chamber, the fourth chamber and the leakage oil tank 16.

[0037] Specifically, the balancing system includes a balancing chamber, in which a balancing piston 13 is installed. The balancing piston 13 divides the balancing chamber into a fifth chamber 131 and a sixth chamber 132. The fifth chamber 131 is connected to the fourth chamber 122. A balancing spring is installed in the fifth chamber 131. The sixth chamber 132 is connected to a leakage oil tank 16, which refers to the external environment.

[0038] In the balancing system of this invention, the balancing piston serves to balance the pressure between the instrument's internal and external environments. Specifically, changes in downhole temperature and pressure cause variations in the volume of hydraulic oil in the fifth chamber. The balancing piston moves within the balancing chamber to compensate for the oil volume changes and balance the pressure inside and outside the instrument, ensuring the pressure difference remains within a reasonable range to guarantee the crawler's normal operation. In practical use, both the fifth chamber 131 and the fourth chamber 122 are filled with hydraulic oil.

[0039] The pipeline between the fifth chamber 131 and the fourth chamber 122 is connected to one end of the pressure relief valve 15 and the inlet of the second overflow valve 14. The other end of the pressure relief valve 15 and the outlet of the second overflow valve 14 are both connected to the leakage oil tank 16, and the oil tank is connected to one end of the pressure relief valve 15.

[0040] The purpose of installing the second overflow valve 14 and the pressure relief valve 15 here is to ensure system safety. When the internal pressure of the crawler rises abnormally due to sudden situations such as piston jamming or gas mixing, the second overflow valve 14 plays a role in stabilizing pressure and overflowing safety protection. When the downhole temperature is too high and the volume of the oil in the instrument expands due to heat and exceeds the compensation range of the balance piston, the pressure relief valve can release a portion of the hydraulic oil in the fourth chamber, the fifth chamber and the oil tank into the well fluid, so as to stabilize the pressure difference between the inside and outside of the instrument under extreme working conditions.

[0041] The hydraulic circuit system also includes a third directional valve 21. The inlet of the third directional valve 21 is connected to the pipeline between the check valve 6 and the hydraulic pump 3, and the outlet of the third directional valve 21 is connected to the oil tank. Under normal conditions, the third directional valve 21 is set to a normally open state that allows the hydraulic oil between the check valve 6 and the hydraulic pump 3 to flow back to the oil tank.

[0042] This embodiment of the invention, through the setting of the third directional valve 21, achieves the purpose of relieving the pressure between the hydraulic pump 3 and the check valve 6, thereby improving the service life of the hydraulic pump 3. Furthermore, the third directional valve 21 of this embodiment can be used to fine-tune and increase the pressure of the hydraulic oil in the first chamber 111. Specifically, during the process of the hydraulic pump 3 pumping hydraulic oil from the oil chamber through the check valve 6 into the first chamber 111 of the hydraulic oil chamber 11, the third directional valve 21 is in a closed state, preventing the hydraulic oil between the check valve 6 and the hydraulic pump 3 from flowing back to the oil tank. During the process of the push arm pushing against the well wall, when the pressure of the hydraulic oil in the first chamber 111 decreases, the hydraulic pump 3 is restarted, and the third directional valve 21 is adjusted back to its normally open state. At this time, part of the hydraulic oil pumped by the hydraulic pump 3 flows back to the oil tank through the third directional valve 21, and the other part acts on the first chamber 111 through the check valve 6, thus achieving the purpose of fine-tuning and increasing the pressure of the hydraulic oil in the first chamber 111.

[0043] By combining the settings of the first reversing valve 7 and the third reversing valve 21, this embodiment of the invention achieves accurate adjustment of the magnitude of the crawler arm's pushing force.

[0044] This invention also provides a downhole crawler, which is equipped with a downhole crawler hydraulic circuit system according to any of the above embodiments.

[0045] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0046] Furthermore, the terms "a," "two," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0047] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A hydraulic circuit system for a downhole crawler, characterized in that, Includes a hydraulic pump (3), a hydraulic oil chamber (11), and a first directional valve (7). The hydraulic oil chamber (11) is equipped with a push piston that divides it into a first chamber (111) and a second chamber (112). The outlet of the hydraulic pump (3) is connected to the first chamber (111) via a check valve (6). The check valve (6) is configured to allow hydraulic oil pumped by the hydraulic pump (3) to flow into the first chamber (111). The inlet of the first directional valve (7) is connected to the pipeline between the check valve (6) and the first chamber (111). The outlet of the reversing valve (7) and the second chamber (112) are both connected to the oil tank. The first reversing valve (7) is normally set to allow the hydraulic oil in the first chamber (111) to flow back to the oil tank through it. The piston rod of the push piston extends out of the second chamber (112) and is used to connect to the crawler arm of the downhole crawler. A retraction spring is provided in the second chamber (112). The retraction spring is used to drive the push piston to squeeze the first chamber (111) to move when the first reversing valve (7) is in the normally open state, so that the crawler arm can be retracted.

2. The hydraulic circuit system for the downhole crawler according to claim 1, characterized in that, A filter (4) is provided between the oil outlet of the hydraulic pump (3) and the check valve (6). A pressure sensor (10) is provided between the check valve (6) and the first cavity (111). A first overflow valve (5) is also provided between the first cavity (111) and the oil tank.

3. The hydraulic circuit system for the downhole crawler according to claim 1, characterized in that, The hydraulic pump (3) is connected to a hydraulic motor (2), which is used to drive the hydraulic pump (3) to work.

4. The hydraulic circuit system for the downhole crawler according to claim 1, characterized in that, The hydraulic circuit system also includes a pressure stabilizing system, which is used to stabilize the pressure in the first cavity (111) so that the crawler arm is in a stable pushing state.

5. The hydraulic circuit system for the downhole crawler according to claim 4, characterized in that, The pressure stabilizing system includes a pressure stabilizing chamber, in which an energy storage piston (12) is provided. The energy storage piston (12) divides the pressure stabilizing chamber into a third chamber (121) and a fourth chamber (122). The third chamber (121) is connected to the pipeline between the one-way valve (6) and the first chamber (111). The fourth chamber (122) is provided with an energy storage spring. The energy storage spring is configured to be gradually compressed after the hydraulic oil enters the third chamber, so that when the pressure of the first chamber (111) decreases, it drives the energy storage piston (12) to squeeze the third chamber (121) so that the pressure of the first chamber (111) is in a stable state.

6. The hydraulic circuit system for the downhole crawler according to claim 5, characterized in that, The hydraulic circuit system also includes a balancing system for balancing the pressure between the oil tank, the first cavity, the second cavity, the fourth cavity (122), and the leakage oil tank (16).

7. The hydraulic circuit system for the downhole crawler according to claim 6, characterized in that, The balancing system includes a balancing chamber, in which a balancing piston (13) is provided. The balancing piston (13) divides the balancing chamber into a fifth chamber (131) and a sixth chamber (132). The fifth chamber (131) is connected to the fourth chamber (122). A balancing spring is provided in the fifth chamber (131). The sixth chamber (132) is connected to the leakage oil tank (16).

8. The hydraulic circuit system for the downhole crawler according to claim 7, characterized in that, The pipeline between the fifth chamber (131) and the fourth chamber (122) is connected to one end of the pressure relief valve (15) and the inlet of the second overflow valve (14). The other end of the pressure relief valve (15) and the outlet of the second overflow valve (14) are both connected to the leakage oil tank (16). The oil tank is connected to one end of the pressure relief valve (15).

9. The hydraulic circuit system for the downhole crawler according to claim 1, characterized in that, The hydraulic circuit system also includes a second directional valve (8), the inlet of which is connected to the pipeline between the check valve (6) and the first chamber (111), the outlet of which is connected to the oil tank, and the second directional valve (8) is normally set to a closed state that prevents the hydraulic oil in the first chamber (111) from flowing back to the oil tank.

10. The hydraulic circuit system for the downhole crawler according to claim 1, characterized in that, The hydraulic circuit system also includes a third directional valve (21), the inlet of which is connected to the pipeline between the check valve (6) and the hydraulic pump (3), and the outlet of which is connected to the oil tank. The third directional valve (21) is normally configured to allow the hydraulic oil between the check valve (6) and the hydraulic pump (3) to flow back to the oil tank through it.

11. A downhole crawler, characterized in that, It is equipped with the downhole crawler hydraulic circuit system as described in any one of claims 1-10.

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