Underground coring system

Abstract

The invention discloses an underground coring system which can provide bit pressure in a hydraulic mode, does not need additional balance weight and can ensure accurate adjustment of the bit pressure. The underground coring device comprises an underground coring device body and an operation carrier, the underground coring device body comprises a hydraulic feeding assembly and a rotary sampling assembly, the hydraulic feeding assembly comprises a power assembly and a hydraulic oil cylinder assembly, the hydraulic oil cylinder assembly comprises a first cavity and a second cavity, and the power assembly is connected with the first cavity through a first oil way; the power assembly is connected with the second cavity through a second oil way. When the power assembly extracts oil from the first cavity and conveys the oil to the second cavity, the hydraulic oil cylinder assembly drives the rotary sampling assembly to drill into hard rock; when the power assembly extracts oil from the second cavity and conveys the oil to the first cavity, the hydraulic oil cylinder assembly drives the rotary sampling assembly to be separated from the hard rock; the operation carrier is provided with winding and unwinding equipment and a cable connected with the hydraulic feeding assembly, and the winding and unwinding equipment can drive the underground coring device to dive or float upwards by unwinding or winding the cable.

Description

Technical Field

[0001] This application relates to the field of drilling and sampling equipment technology, and in particular to a downhole coring system. Background Technology

[0002] In deep hard rock core drilling operations, the main challenge lies in maintaining a stable and high-speed operation of the drill bit at the bottom of the well. Insufficient drill bit speed directly leads to low drilling efficiency and seriously affects the quality and integrity of the obtained core samples. To solve this problem, the current ocean drilling field commonly uses downhole mud motors as the power source for core drilling tools; meanwhile, some studies have proposed using downhole electric drills driven by electric motors as an alternative.

[0003] On the one hand, existing mud motor drive technology has significant limitations. First, its operation relies on a large amount of mud circulation, with the mud being transported to the bottom of the well via a long drill string, resulting in significant energy loss. Second, when operating at sea, the drilling vessel's hull experiences heave and sway due to waves, which can easily lead to unstable downhole drilling pressure and affect drilling continuity. Furthermore, this type of drill string typically has a small core diameter while the drill bit's cutting surface is large, making it prone to causing harmful radial vibrations during rotation, thereby reducing core recovery rate and quality.

[0004] On the other hand, current electric drilling tools also face technical bottlenecks. Their structure often includes moving parts such as roller cone arms and rotating blocks, which extend outside the casing, making it difficult for the roller cones to effectively apply and maintain sufficient drilling pressure. Currently, these types of drilling tools mainly rely on gravity to provide drilling pressure, often requiring significant additional counterweights. This not only weakens the effective load-bearing capacity of the steel cable but also makes precise adjustment of drilling pressure difficult. Furthermore, this technology lacks a clear stroke termination signal, making it difficult for operators to accurately determine whether the drilling process is complete, affecting operation control and core harvesting. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a downhole coring system that can provide drilling pressure hydraulically without the need for additional counterweights and can ensure precise adjustment of drilling pressure.

[0006] According to a first aspect embodiment of the present application, the downhole coring system includes a downhole coring device and a working vehicle. The downhole coring device includes a hydraulic feed assembly and a rotary sampling assembly. The hydraulic feed assembly includes a power assembly and a hydraulic cylinder assembly. The hydraulic cylinder assembly includes a first cavity and a second cavity. The power assembly is connected to the first cavity via a first oil circuit and to the second cavity via a second oil circuit. When the power assembly extracts oil from the first cavity and delivers it to the second cavity, the hydraulic cylinder assembly drives the rotary sampling assembly to drill into hard rock. When the power assembly extracts oil from the second cavity and delivers it to the first cavity, the hydraulic cylinder assembly drives the rotary sampling assembly to detach from the hard rock. The working vehicle is equipped with a winding and unwinding device and a cable connected to the hydraulic feed assembly. The winding and unwinding device can drive the downhole coring device to submerge or surface by unwinding or rewinding the cable.

[0007] The downhole coring system according to the embodiments of this application has at least the following beneficial effects: the working vehicle is used to carry the downhole coring device. When the working vehicle reaches the preset position above the water, the launching and retracting equipment drives the downhole coring device to descend via a cable. After the downhole coring device descends to the preset depth, the power component delivers the oil in the first chamber to the second chamber, causing the hydraulic cylinder assembly and the rotary sampling assembly to feed towards the hard rock. At the same time, the power component can also drive the rotary sampling assembly to rotate, ensuring that the rotary sampling assembly drills into the hard rock to obtain a core sample. After obtaining the core sample, the power component delivers the oil in the second chamber to the first chamber, causing the hydraulic cylinder assembly and the rotary sampling assembly to gradually move away from the hard rock. The working vehicle then pulls the downhole coring device above the water surface via a cable to complete the sampling. Since the sampling feed process is hydraulically driven, there is no need to set an excessively large counterweight in the downhole coring device, which is beneficial to improving the effective load capacity of the downhole coring device. Furthermore, the hydraulically driven feed process can also ensure precise adjustment of drilling pressure and guarantee sampling quality.

[0008] According to some embodiments of this application, the hydraulic cylinder assembly includes a cylinder body and a piston rod, the piston rod being slidably inserted into the cylinder body, and the rotary sampling assembly includes a sampling component, the sampling component being fixedly connected to the cylinder body; when the cylinder body slides relative to the piston rod, the cylinder body drives the sampling component to move closer to or away from the hard rock; The piston rod divides the internal space of the cylinder into a second cavity closer to the hard rock and a first cavity farther away from the hard rock.

[0009] According to some embodiments of this application, the hydraulic feed assembly further includes an oil tank, which is connected to the first oil circuit and the second oil circuit via a pipeline. The pipeline portion connecting the oil tank to the first oil circuit is provided with a first check valve, and the pipeline portion connecting the oil tank to the second oil circuit is provided with a second check valve.

[0010] According to some embodiments of this application, the hydraulic feed assembly further includes a first relief valve and a second relief valve. The first relief valve is connected to the first oil circuit and the second oil circuit through a pipeline. When the pressure in the first oil circuit is greater than a set value, the oil overflows from the first oil circuit to the second oil circuit through the first relief valve. The second relief valve is connected to the first oil circuit and the second oil circuit through a pipeline. When the pressure in the second oil circuit is greater than a set value, the oil overflows from the second oil circuit to the first oil circuit through the second relief valve.

[0011] According to some embodiments of this application, the power assembly includes a driver and a bidirectional hydraulic pump. The driver is connected to the cable and the bidirectional hydraulic pump is connected via a drive shaft. The driver is used to drive the bidirectional hydraulic pump to output flow in a first direction or flow in a second direction.

[0012] According to some embodiments of this application, the rotary sampling assembly further includes a hollow torque transmission outer cylinder, the torque transmission outer cylinder is fixedly connected to the drive shaft, the hydraulic cylinder assembly is disposed inside the torque transmission outer cylinder, and the cylinder body is slidably connected to the torque transmission outer cylinder; when the cylinder body slides relative to the torque transmission outer cylinder, the cylinder body drives the sampling component to approach or move away from the hard rock.

[0013] According to some embodiments of this application, the downhole coring device further includes a sensor assembly, which includes a level sensor connected to the oil tank, a first pressure sensor connected to the first oil circuit, and a second pressure sensor connected to the second oil circuit. The cable is connected to an electrical control compartment, and the electrical control compartment is connected to the sensor assembly via a signal line. The downhole coring device also includes a power supply component, which can convert the mechanical energy of the power component into electrical energy and supply power to the sensor component.

[0014] According to some embodiments of this application, the downhole coring device further includes a main anti-torsion assembly and an auxiliary anti-torsion assembly sleeved on the outside of the cable. The main anti-torsion assembly is fixedly connected to the power assembly. When the downhole coring device is inserted into the bottom drill string assembly, the auxiliary anti-torsion assembly expands outward to contact the inner wall of the bottom drill string assembly, and the main anti-torsion assembly expands outward to contact and engage with the groove located on the inner wall of the bottom drill string assembly.

[0015] According to some embodiments of this application, the downhole coring device further includes an electric slip ring assembly located between the main anti-torsion assembly and the auxiliary anti-torsion assembly. The electric slip ring assembly includes a first rotating part and a second rotating part. The first rotating part is fixedly connected to the auxiliary anti-torsion assembly, and the second rotating part is fixedly connected to the main anti-torsion assembly. The first rotating part and the second rotating part are rotatably connected.

[0016] According to some embodiments of this application, the cable is connected to an electrical control cabin, and the downhole coring device further includes a tension limiter fixedly connected to the electrical control cabin. The tension limiter includes a first connecting part and a second connecting part, which are connected by a shear pin. When the tension on the shear pin is greater than a preset value, the shear pin breaks, thereby separating the first connecting part and the second connecting part.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The present application will be further illustrated below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments illustrated in the following drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application.

[0019] Figure 1 This is a schematic diagram of the downhole coring system according to an embodiment of this application; Figure 2 This is a schematic diagram of the power component and hydraulic cylinder component in the downhole coring device of the downhole coring system according to an embodiment of this application; Figure 3 This is a schematic diagram of the external appearance of the downhole coring device in the downhole coring system of this application embodiment; Figure 4 This is a schematic diagram of the internal structure of the downhole coring device in the downhole coring system of this application embodiment; Figure 5 This is the downhole coring system according to the embodiments of this application. Figure 4 A magnified view of part A in the middle; Figure 6 This is a schematic diagram of the control principle of the downhole coring system in an embodiment of this application.

[0020] Figure label: 100. Downhole coring device; 101. Hydraulic feed assembly; 102. Power assembly; 103. Hydraulic cylinder assembly; 201. First oil passage; 202. Second oil passage; 203. First chamber; 204. Second chamber; 205. Cylinder; 206. Piston rod; 207. Torque transmission outer cylinder; 208. Sampling component; 209. First check valve; 210. Second check valve; 211. First relief valve; 212. Second relief valve; 213. Actuator; 214. Bidirectional hydraulic pump; 300. Sensor assembly; 301. Liquid level sensor; 302. First pressure sensor; 303. Second pressure sensor; 304. Electrical control compartment; 401. Power supply assembly; 402. Main anti-torsion assembly; 403. Auxiliary anti-torsion assembly; 404. Bottom drill string assembly; 501. Electric slip ring assembly; 502. First rotating part; 503. Second rotating part; 504. Tension limiter; 505. First connecting part; 506. Second connecting part; 507. Shear pin; 601. Operating vehicle; 602. Retrieval and deployment equipment; 603. Cables; 604. Deck electrical control box. Detailed Implementation

[0021] The embodiments of this application are described in detail below with reference to the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0022] In the description of this application, it should be understood that the terms "center", "middle", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0023] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In the description of this application, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] In the description of this application, the use of terms such as "one embodiment," "some embodiments," "an example," "some instances," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0026] This application provides a downhole coring system, which includes a downhole coring device 100 and a work vehicle 601. The downhole coring device 100 collects core samples underwater by drilling. After collecting a sufficient amount of core sample, the device is retrieved from the water, bringing the core sample to the surface, thus obtaining the core sample. Notably, during the drilling process, the downhole coring device 100 provides drilling pressure hydraulically, eliminating the need for excessive counterweights. This improves the effective load capacity of the device and ensures precise adjustment of the drilling pressure, guaranteeing sample quality.

[0027] Furthermore, the working vehicle 601 can transport the downhole coring device 100 to the target water area, thereby ensuring that the downhole coring device 100 can dive and float in the target water area, improving the convenience of obtaining core samples.

[0028] The contents of this application are described in detail below with reference to specific embodiments. It should be noted that the following description is merely illustrative and not a specific limitation of this application.

[0029] like Figure 1 , Figure 2 and Figure 3As shown, in some embodiments, the downhole coring apparatus 100 includes a hydraulic feed assembly 101 and a rotary sampling assembly. The rotary sampling assembly is capable of drilling and sampling hard rock. During the sampling process, the rotary sampling assembly rotates while simultaneously feeding towards the hard rock. The hydraulic feed assembly 101 is connected to the rotary sampling assembly and is used to implement the feeding process during drilling and sampling.

[0030] Furthermore, the hydraulic feed assembly 101 includes a power assembly 102 and a hydraulic cylinder assembly 103. The hydraulic cylinder assembly 103 is connected to the rotary sampling assembly. When the hydraulic cylinder assembly 103 moves, it drives the rotary sampling assembly to move, thereby realizing the feeding process of the rotary sampling assembly. At the same time, the power assembly 102 can drive the hydraulic cylinder assembly 103 to move.

[0031] Furthermore, the hydraulic cylinder assembly 103 includes a first cavity 203 and a second cavity 204. The internal spaces of the first cavity 203 and the second cavity 204 can both contain hydraulic oil. The power assembly 102 can drive the hydraulic oil to flow between the first cavity 203 and the second cavity 204, thereby realizing the movement of the hydraulic cylinder assembly 103.

[0032] Specifically, the power assembly 102 is provided with a first oil passage 201 and a second oil passage 202. The power assembly 102 is connected to the first cavity 203 through the first oil passage 201, and the power assembly 102 is connected to the second cavity 204 through the second oil passage 202. When the power assembly 102 draws oil from the first cavity 203 and delivers the oil to the second cavity 204, the oil in the first cavity 203 decreases and the oil in the second cavity 204 increases. This causes the pressure in the first cavity 203 to decrease and the pressure in the second cavity 204 to increase, resulting in the hydraulic cylinder assembly 103 moving accordingly based on the pressure change. At this time, the hydraulic cylinder assembly 103 can drive the rotary sampling assembly to drill into hard rock through its movement. When the power assembly 102 draws oil from the second chamber 204 and delivers the oil to the first chamber 203, the oil in the second chamber 204 decreases while the oil in the first chamber 203 increases. This causes the pressure in the second chamber 204 to decrease and the pressure in the first chamber 203 to increase, which in turn causes the hydraulic cylinder assembly 103 to move accordingly based on the pressure change. At this time, the hydraulic cylinder assembly 103 can drive the rotating sampling assembly to detach from the hard rock through the movement, thereby completing the core sampling process.

[0033] In addition, the working vehicle 601 can be a mother ship, which can transport the downhole coring device 100 to the target water area, facilitating the submersion of the downhole coring device 100 in the target water area to achieve core sampling. When the working vehicle 601 is a mother ship, the deck of the working vehicle 601 is equipped with a deployment and retrieval device 602 and a cable 603. On one hand, the cable 603 is connected to the hydraulic feed assembly 101; on the other hand, the cable 603 is connected to the deployment and retrieval device 602. It is understood that the deployment and retrieval device 602 can either reel in or unreel in the cable 603. When the deployment and retrieval device 602 unreels the cable 603, the downhole coring device 100 can submerge from the water surface to the bottom; when the deployment and retrieval device 602 reels in the cable 603, the downhole coring device 100 can rise from the bottom to the surface.

[0034] Specifically, the deck of the working vehicle 601 is also equipped with a deck electrical control box 604. The deck electrical control box 604 contains a frequency converter, operating system, etc., and is used for power supply and control of the downhole coring device 100. Cable 603 is connected to the deck electrical control box 604. Furthermore, cable 603 can be armored optical fiber cable. Armored optical fiber cable includes outer steel wire, cable and optical fiber. The cable is used for power supply, and the optical fiber is used for transmitting electrical signals. The outer steel wire wraps the cable and optical fiber and is vulcanized and bonded to the load-bearing head of downhole coring device 100 to ensure the connection between cable 603 and downhole coring device 100. At the same time, the take-up and drop device 602 can be an electro-optical winch. The electro-optical winch winds the armored optical fiber cable and is used for take-up and drop of the armored optical fiber cable.

[0035] like Figure 2 and Figure 4 As shown, in some embodiments, the hydraulic cylinder assembly 103 includes a cylinder body 205 and a piston rod 206, the piston rod 206 being slidably inserted into the cylinder body 205 to facilitate relative sliding between the cylinder body 205 and the piston rod 206.

[0036] Furthermore, the rotary sampling assembly includes a sampling component 208 for drilling and collecting core samples, which is fixedly connected to the cylinder 205. Since the piston rod 206 of this application is in a fixed position, when the cylinder 205 slides relative to the piston rod 206, the cylinder 205 can move the sampling component 208 closer to or away from the hard rock.

[0037] Specifically, the end of the piston rod 206 divides the internal space of the cylinder 205 into a first chamber 203 and a second chamber 204. The first chamber 203 is far from the hard rock, and the main body of the piston rod 206 exists within the first chamber 203. Meanwhile, the second chamber 204 is close to the hard rock, and its interior is hollow, without the piston rod 206. Therefore, when oil is transported from the first chamber 203 to the second chamber 204, the cylinder 205 moves towards the hard rock, facilitating core sample collection; similarly, when oil is transported from the second chamber 204 to the first chamber 203, the cylinder 205 retracts away from the hard rock, facilitating the removal of the collected core sample from the hard rock.

[0038] like Figure 2 As shown, in some embodiments, the hydraulic feed assembly 101 further includes an oil tank for storing oil for later use. The oil tank is connected to a first oil passage 201 via a pipeline, and also to a second oil passage 202 via a pipeline, facilitating oil supply from the oil tank to the first oil passage 201 and oil return from the second oil passage 202 to the oil tank.

[0039] Furthermore, the pipeline connecting the oil tank to the first oil circuit 201 is equipped with a first check valve 209, and the pipeline connecting the oil tank to the second oil circuit 202 is equipped with a second check valve 210. The first check valve 209 and the second check valve 210 can ensure that the oil flows between the oil tank, the first oil circuit 201 and the second oil circuit 202 in a preset manner, and prevent the oil from flowing in reverse.

[0040] Specifically, the fuel tank has a main pipeline, which branches into two branches. One branch connects to the first fuel line 201, and the other branch connects to the second fuel line 202. It is understood that a first check valve 209 is installed on the branch connecting the fuel tank to the first fuel line 201, and a second check valve 210 is installed on the branch connecting the fuel tank to the second fuel line 202.

[0041] In addition, the oil tank in this application is a piston-type oil tank, with oil on one side of the piston and seawater on the other side, which enables the piston-type oil tank to have oil storage and pressure compensation functions.

[0042] In some embodiments, the hydraulic feed assembly 101 further includes a first relief valve 211 and a second relief valve 212. The first relief valve 211 is connected to a first oil passage 201 and a second oil passage 202 via a pipeline. Under certain circumstances, the first relief valve 211 opens the first oil passage 201 and the second oil passage 202, allowing oil to be delivered from the first pipeline to the second pipeline. However, the first relief valve 211 is not normally open; oil can only pass through the first relief valve 211 when the pressure in the first oil passage 201 is greater than a set value.

[0043] Similarly, the second relief valve 212 is connected to the first oil passage 201 and the second oil passage 202 via a pipeline. Under certain conditions, the second relief valve 212 opens the first oil passage 201 and the second oil passage 202, allowing oil to be transported from the second oil passage 202 to the first oil passage 201. However, the second relief valve 212 does not open under normal conditions; oil can only pass through the second relief valve 212 when the pressure in the second oil passage 202 is greater than a set value.

[0044] Specifically, the first relief valve 211 and the second relief valve 212 can adjust the above-mentioned set values ​​according to the actual pressure requirements, thereby achieving conduction under a specific relief pressure.

[0045] In some embodiments, the power assembly 102 includes a driver 213 and a bidirectional hydraulic pump 214. The driver 213 may be a permanent magnet variable frequency motor. The driver 213 is connected to the bidirectional hydraulic pump 214, and the two ends of the bidirectional hydraulic pump 214 are respectively connected to a first oil passage 201 and a second oil passage 202. It is understood that the driver 213 can start the bidirectional hydraulic pump 214 in different ways, causing the bidirectional hydraulic pump 214 to deliver oil in different flow directions.

[0046] Specifically, the driver 213 is connected to cable 603, which provides power to the driver 213 to ensure its normal operation. The driver 213 is connected to a bidirectional hydraulic pump 214 via a drive shaft, thereby driving the bidirectional hydraulic pump 214 to output flow in either a first direction or a second direction. Here, the first direction refers to... Figure 2 The X direction in the text refers to the oil being transported from the first oil passage 201 to the second oil passage 202; the second direction here is... Figure 2 In the Y direction, the oil is transported from the second oil passage 202 to the first oil passage 201.

[0047] During the actual operation of the hydraulic feed assembly 101, the actuator 213 drives the bidirectional hydraulic pump 214 to draw oil from the first oil passage 201 and deliver it to the second oil passage 202. The oil supplied to the bidirectional hydraulic pump 214 by the first oil passage 201 comes from the first chamber 203 and the oil tank. The oil from the oil tank to the first oil passage 201 passes through the first check valve 209, and the oil from the second oil passage 202 is pumped to the second chamber 204, causing the cylinder 205 to drive the sampling component 208 to feed. When the feed direction is overloaded or the cylinder 205 reaches the extended end, the system will detect overpressure and stop the operation of the actuator 213; if the system malfunctions and fails to stop the actuator 213, the second relief valve 212 will overflow, thereby protecting the downhole coring device 100.

[0048] Correspondingly, the actuator 213 can also drive the bidirectional hydraulic pump 214 to draw oil from the second oil passage 202 and send it to the first oil passage 201. High pressure is generated in the first oil passage 201, opening the second check valve 210 and simultaneously pressurizing the first chamber 203, causing the cylinder 205 to retract the sampling component 208. Oil from the second chamber 204 enters the second oil passage 202. At this time, part of the oil in the second oil passage 202 is supplied to the bidirectional hydraulic pump 214, and the other part returns to the oil tank through the open second check valve 210. When there is an overload in the retraction direction or the cylinder 205 reaches the retraction end, the system will detect overpressure and stop the operation of the actuator 213; if the system malfunctions and fails to stop the actuator 213, the first overflow valve 211 overflows, thereby protecting the downhole coring device 100.

[0049] like Figure 4 As shown, in some embodiments, the rotary sampling assembly further includes a hollow torque-transmitting outer cylinder 207, with a hydraulic cylinder assembly 103 disposed inside the torque-transmitting outer cylinder 207. Simultaneously, the torque-transmitting outer cylinder 207 is slidably connected to the cylinder body 205, preventing relative rotation between them and allowing only relative sliding along the feed direction or its opposite direction. It is understood that when the cylinder body slides relative to the torque-transmitting outer cylinder 207, the cylinder body drives the sampling component 208 towards or away from the hard rock.

[0050] Furthermore, the torque transmission outer cylinder 207 is fixedly connected to the drive shaft of the driver 213. When the driver 213 outputs rotational motion, the driver 213 drives the torque transmission outer cylinder 207 to rotate through the drive shaft, which in turn drives the sampling component 208 to rotate.

[0051] Specifically, the outer wall of the cylinder 205 and the inner wall of the torque transmission outer cylinder 207 are connected by a key, so that the cylinder 205 and the torque transmission outer cylinder 207 can only slide relative to each other and cannot rotate relative to each other, thus ensuring the normal transmission of torque.

[0052] like Figure 2 and Figure 6 As shown, in some embodiments, the downhole coring device 100 further includes a sensor assembly 300, which includes a level sensor 301, a first pressure sensor 302, and a second pressure sensor 303. The level sensor 301 is connected to the oil tank, the first pressure sensor 302 is connected to the first oil passage 201 to detect the pressure within the first cavity 203, and the second pressure sensor 303 is connected to the second oil passage 202 to detect the pressure within the second cavity 204.

[0053] Furthermore, cable 603 is connected to electrical control compartment 304, which is connected to sensor assembly 300 via signal line and is used to realize downhole data processing and photoelectric conversion of signals.

[0054] In addition, the downhole coring device 100 also includes a power supply assembly 401, which can convert the mechanical energy of the drive shaft rotation into electrical energy, thereby supplying power to structures such as the sensor assembly 300 and the electrical control cabin 304.

[0055] Specifically, cable 603 is split into two in the downhole coring device 100, one branch being a power cable and the other an optical fiber. The power cable connects to and powers the actuator 213. The optical fiber connects to the electrical control cabin 304, thereby transmitting control signals to the electrical control cabin 304. Furthermore, the power supply assembly 401 includes an electromagnetic coil, a battery, and a power management module. The electromagnetic coil converts the mechanical energy of the rotating drive shaft into electrical energy. The electrical energy charges the battery through the power management module, or the generated electrical energy directly powers structures such as the sensor assembly 300.

[0056] like Figure 4 As shown, in some embodiments, the downhole coring device 100 further includes a main anti-torsion assembly 402 and an auxiliary anti-torsion assembly 403, both of which are sleeved on the outside of the cable 603. The main anti-torsion assembly 402 is fixedly connected to the power assembly 102, and the auxiliary anti-torsion assembly 403 is spaced apart from the main anti-torsion assembly 402.

[0057] Furthermore, both the main anti-torsion assembly 402 and the auxiliary anti-torsion assembly 403 are equipped with structures capable of expanding outwards. When the downhole coring device 100 is inserted into the bottom drill string assembly 404, the auxiliary anti-torsion assembly 403 expands outwards, thereby contacting the inner wall of the bottom drill string assembly 404 to increase the friction between the downhole coring device 100 and the bottom drill string assembly 404. Similarly, the main anti-torsion assembly 402 can also expand outwards, thereby contacting and engaging with the groove located on the inner wall of the bottom drill string assembly 404. This not only increases the friction between the downhole coring device 100 and the bottom drill string assembly 404 but also provides axial positioning for the downhole coring device 100.

[0058] Specifically, the main anti-torsion assembly 402 mainly includes an expandable spring clip and a relatively large-diameter seat ring. The total length of the seat ring and the spring clip corresponds to the length of the groove on the inner wall of the bottom drill string assembly 404, thereby engaging them to restrict the position of the downhole coring device 100 relative to the bottom drill string assembly 404. Simultaneously, the opening spring clip engages with the groove in the bottom drill string assembly 404, providing torsional reaction force. Further, the auxiliary anti-torsion assembly 403 includes a spring and at least two radially outward-flexible friction components. When the downhole coring device 100 is positioned, the friction components and the inner wall of the bottom drill string assembly 404 contact under spring pressure, generating a certain anti-torsional friction force. This prevents the downhole coring device 100 from causing the cable 603 to twist before the main anti-torsion assembly 402 is engaged, thus avoiding damage to the cable 603 due to twisting.

[0059] In some embodiments, the downhole coring apparatus 100 further includes an electric slip ring assembly 501, which is located between the main anti-torsion assembly 402 and the auxiliary anti-torsion assembly 403.

[0060] The slip ring assembly 501 includes a first rotating part 502 and a second rotating part 503. The first rotating part 502 is fixedly connected to the auxiliary anti-torsion assembly 403, and the second rotating part 503 is fixedly connected to the main anti-torsion assembly 402. The first rotating part 502 and the second rotating part 503 are rotatably connected.

[0061] Specifically, the first rotating part 502 and the second rotating part 503 are multi-contact mechanical components that can slide relative to each other, allowing the upper and lower connected structures of the slip ring assembly 501 to rotate relative to each other. A rolling bearing and a tapered roller bearing are installed between the first rotating part 502 and the second rotating part 503. When the lower structure of the slip ring assembly 501 rotates, the upper structure of the slip ring assembly 501 is prevented from rotating along with it, thereby preventing damage to the cable 603 caused by twisting.

[0062] like Figure 5 As shown, in some embodiments, the downhole coring device 100 also includes a tension limiter 504, which is fixedly connected between the electrical control compartment 304 and the load-bearing head of the downhole coring device 100. When the downhole coring device 100 is operating normally, the tension limiter 504 maintains the integrity of the downhole coring device 100; however, if the downhole coring device 100 suddenly fails to be retrieved, the tension limiter 504 can be disassembled by pulling the cable 603, thereby providing a release function in emergency situations.

[0063] Furthermore, the tension limiter 504 includes a first connecting portion 505 and a second connecting portion 506, which are connected by a shear pin 507. A portion of the shear pin 507 is fixed to the first connecting portion 505, and another portion is fixed to the second connecting portion 506. When the tension on the shear pin 507 exceeds a preset value, the shear pin 507 breaks, thereby separating the first connecting portion 505 and the second connecting portion 506, ensuring the cable 603 can be retrieved.

[0064] In actual implementation, when the downhole coring device 100 is lifted on the deck via armored fiber optic cable, the auxiliary anti-torsion assembly 403 retracts, and the main anti-torsion assembly 402 also retracts. With manual assistance, the downhole coring device 100 is then lowered into the bottom drill string assembly 404. When the downhole coring device 100 is in position, the main anti-torsion assembly 402 opens and engages with the groove on the inner wall of the bottom drill string assembly 404. The auxiliary anti-torsion assembly 403 also opens, and under the pressure of the spring, the friction plate presses tightly against the inner wall of the bottom drill string assembly 404. At this point, the relative rotation and axial movement of the downhole coring device 100 and the bottom drill string assembly 404 are restricted, thus achieving the positioning of the downhole coring device 100.

[0065] After the device is lowered to the bottom of the well, mud is introduced into the bottom drill string assembly 404. The mud passes through the space between the downhole coring device 100 and the bottom drill string assembly 404 to reach the bottom of the well, and then returns to the seabed surface through the space between the bottom drill string assembly 404 and the formation. The flowing mud can dissipate heat from the drive unit 213 and carry away materials such as rock cuttings from the bottom of the well.

[0066] During the drilling start-up process, drilling parameters are set via the deck electrical control box 604, and the start button is pressed. The downhole coring device 100 receives frequency converter power and begins to rotate. The driver 213 drives the downhole coring device 100 to work, and the bidirectional hydraulic pump 214 begins to load, causing the pressure in the second oil circuit 202 to increase and driving the cylinder 205 to extend. Because the torque transmission outer cylinder 207 and the drive shaft of the driver 213 are rigidly connected, the cylinder 205 and the torque transmission outer cylinder 207 can move relative to each other axially, and the cylinder 205 is rigidly connected to the sampling component 208. Therefore, after drilling starts, the movement of the sampling component 208 is a composite motion of rotation and axial feed.

[0067] When the drill bit of sampling component 208 contacts hard rock, the drilling pressure increases, and the pressure in the second oil passage 202 further increases until the drilling pressure reaches a preset value. At this point, the second overflow valve 212 overflows, keeping the pressure in the second oil passage 202 constant, i.e., the drilling pressure remains constant. Sampling component 208 continues drilling at constant drilling pressure until a sufficient amount of core sample is collected.

[0068] During the drilling process, signals from the first pressure sensor 302, the second pressure sensor 303, and the liquid level sensor 301 are collected and processed by the electrical control room 304 and converted into optical signals. The optical signals are transmitted to the deck electrical control box 604 via cable 603, and the drilling pressure and drilling progress are finally calculated through conversion.

[0069] When the level sensor 301 detects that the oil level in the tank has dropped to a specified value and the torque of the drive 213 has decreased significantly, it indicates that the drilling process has ended, and drilling is stopped at this time. The deck electrical control box 604 disconnects the frequency converter power supply of the drive 213 and stops the mud pumping.

[0070] During the retrieval of the downhole coring device 100, the photoelectric winch lifts the cable 603, which pulls the downhole coring device 100. As the traction force increases, the friction block of the auxiliary anti-torsion assembly 403 retracts, and the spring-loaded assembly of the main anti-torsion assembly 402 retracts. At this point, the mechanical lock between the downhole coring device 100 and the bottom drill string assembly 404 is released. As the traction force further increases, the hard rock gripped by the sampling component 208 breaks, and the core sample is collected in the sampling component 208. The downhole coring device 100 begins to be lifted towards the wellhead under the traction of the cable 603.

[0071] During the core sample collection process, the downhole coring device 100 is retrieved to the deck under the traction of the cable 603, and the sampling component 208 is disassembled to collect the core, thereby completing the core sample collection.

[0072] During the reset process of the downhole coring device 100, the sampling component 208 is first reinstalled on the downhole coring device 100, and then the downhole coring device 100 is started, causing the drive 213 to reverse. At this time, the first oil circuit 201 is pressurized, driving the cylinder 205 to retract. When the cylinder 205 is fully retracted, the downhole coring device 100 is stopped. Thus, the reset of the downhole coring device 100 is completed, and the next round of core sampling can be carried out.

[0073] In this application, a high-voltage frequency conversion remote power supply is adopted, and the controller of the driver 213 is set on the deck, which reduces the size of the downhole device and improves its flexibility. The downhole power supply component 401 generates electricity through a small generator and stores the energy in a battery, and then supplies power to the sensor component 300 and other structures, so that the low-voltage electricity and the frequency conversion electricity are isolated from each other and do not interfere with each other. The signal of the sensor component 300 is communicated through a bus in the well, reducing the number of lines. The signal of the sensor component 300 is converted into an optical signal for transmission, and optical fiber is used for transmission from the well to the deck, resulting in fast signal transmission speed. In special circumstances such as the downhole coring device 100 getting stuck, the shear pin 507 of the tension limiter 504 can be forcibly pulled off by the cable 603 to realize the emergency recovery of the downhole coring device 100.

[0074] Meanwhile, in cases of slippage of the main anti-torsion assembly 402, the slip ring assembly 501 and the auxiliary anti-torsion assembly 403 cooperate to limit the transmission of downhole rotational torque above the auxiliary anti-torsion assembly 403, preventing torsional damage to the cable 603. Furthermore, the slip ring assembly 501 possesses a certain axial load-bearing capacity. In this application, the drill bit of the sampling component 208 is a thin-walled diamond drill bit with a small cutting edge, resulting in relatively stable rotation of the driver 213 and reducing the likelihood of radial vibration, thus improving the quality of the core sample. When the sampling component 208 obtains the core sample, it extends beyond the bottom drill string assembly 404, allowing for... Based on the recovered core samples, the condition of the formation to be drilled can be known in advance, thereby adopting the optimal drilling method to ensure drilling efficiency and safety. The system of this application has a semi-closed-loop feed control in the well, which can not only achieve constant pressure feed, but also constant speed control. The feed force of the downhole coring device 100 can be controlled by a bidirectional hydraulic pump 214, sensor assembly 300 and overflow valve, etc., which facilitates real-time monitoring of feed pressure. The device of this application has a compact structure and adopts a modular design, with strong expandability. The device of this application can also be applied to geological sampling, bottom exploration and other scenarios.

[0075] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A downhole coring system, characterized in that, include: A downhole coring device includes a hydraulic feed assembly and a rotary sampling assembly. The hydraulic feed assembly includes a power assembly and a hydraulic cylinder assembly. The hydraulic cylinder assembly includes a first chamber and a second chamber. The power assembly is connected to the first chamber via a first oil passage and to the second chamber via a second oil passage. When the power assembly extracts oil from the first chamber and delivers it to the second chamber, the hydraulic cylinder assembly drives the rotary sampling assembly to drill into hard rock. When the power assembly extracts oil from the second chamber and delivers it to the first chamber, the hydraulic cylinder assembly drives the rotary sampling assembly to detach from the hard rock. The working vehicle is equipped with a winding and unwinding device and a cable connected to the hydraulic feed assembly. The winding and unwinding device can drive the downhole coring device to descend or rise by unwinding or rewinding the cable.

2. The downhole coring system according to claim 1, characterized in that, The hydraulic cylinder assembly includes a cylinder body and a piston rod, the piston rod being slidably inserted into the cylinder body. The rotary sampling assembly includes a sampling component, the sampling component being fixedly connected to the cylinder body. When the cylinder body slides relative to the piston rod, the cylinder body drives the sampling component to move closer to or away from the hard rock. The piston rod divides the internal space of the cylinder into a second cavity closer to the hard rock and a first cavity farther away from the hard rock.

3. The downhole coring system according to claim 1, characterized in that, The hydraulic feed assembly also includes an oil tank, which is connected to the first oil circuit and the second oil circuit via pipelines. The pipeline portion connecting the oil tank to the first oil circuit is equipped with a first check valve, and the pipeline portion connecting the oil tank to the second oil circuit is equipped with a second check valve.

4. The downhole coring system according to claim 1, characterized in that, The hydraulic feed assembly also includes a first relief valve and a second relief valve. The first relief valve is connected to the first oil circuit and the second oil circuit through a pipeline. When the pressure in the first oil circuit is greater than a set value, the oil overflows from the first oil circuit to the second oil circuit through the first relief valve. The second relief valve is connected to the first oil circuit and the second oil circuit through a pipeline. When the pressure in the second oil circuit is greater than a set value, the oil overflows from the second oil circuit to the first oil circuit through the second relief valve.

5. The downhole coring system according to claim 2, characterized in that, The power assembly includes a driver and a bidirectional hydraulic pump. The driver is connected to the cable and to the bidirectional hydraulic pump via a drive shaft. The driver is used to drive the bidirectional hydraulic pump to output flow in a first direction or flow in a second direction.

6. The downhole coring system according to claim 5, characterized in that, The rotary sampling assembly also includes a hollow torque transmission outer cylinder, which is fixedly connected to the drive shaft. The hydraulic cylinder assembly is disposed inside the torque transmission outer cylinder, and the cylinder body is slidably connected to the torque transmission outer cylinder. When the cylinder body slides relative to the torque transmission outer cylinder, the cylinder body drives the sampling component to move closer to or away from the hard rock.

7. The downhole coring system according to claim 3, characterized in that, The downhole coring device also includes a sensor assembly, which includes a level sensor connected to the oil tank, a first pressure sensor connected to the first oil circuit, and a second pressure sensor connected to the second oil circuit. The cable is connected to an electrical control compartment, and the electrical control compartment is connected to the sensor assembly via a signal line. The downhole coring device also includes a power supply component, which can convert the mechanical energy of the power component into electrical energy and supply power to the sensor component.

8. The downhole coring system according to claim 1, characterized in that, The downhole coring device also includes a main anti-torsion assembly and an auxiliary anti-torsion assembly sleeved on the outside of the cable. The main anti-torsion assembly is fixedly connected to the power assembly. When the downhole coring device is inserted into the bottom drill string assembly, the auxiliary anti-torsion assembly expands outward to contact the inner wall of the bottom drill string assembly, and the main anti-torsion assembly expands outward to contact and engage with the groove located on the inner wall of the bottom drill string assembly.

9. The downhole coring system according to claim 8, characterized in that, The downhole coring device further includes an electric slip ring assembly located between the main anti-torsion assembly and the auxiliary anti-torsion assembly. The electric slip ring assembly includes a first rotating part and a second rotating part. The first rotating part is fixedly connected to the auxiliary anti-torsion assembly, and the second rotating part is fixedly connected to the main anti-torsion assembly. The first rotating part and the second rotating part are rotatably connected.

10. The downhole coring system according to claim 1, characterized in that, The cable is connected to an electrical control cabin, and the downhole coring device also includes a tension limiter fixedly connected to the electrical control cabin. The tension limiter includes a first connecting part and a second connecting part, which are connected by a shear pin. When the tension on the shear pin is greater than a preset value, the shear pin breaks, thereby separating the first connecting part and the second connecting part.

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