Displacement switching device and operation tubular column

Abstract

The invention relates to the field of oil field oil extraction, and discloses a displacement switching device and an operation tubular column. Comprising a center pipe assembly and an outer sleeve assembly, the center pipe assembly is sleeved with the outer sleeve assembly, and a first containing cavity is formed between the inner wall of the outer sleeve assembly and the outer wall of the center pipe assembly; a position adjusting assembly capable of adjusting and positioning the position of the drilling pipe column in the windowing state and the drilling state is arranged in the first containing cavity. The center pipe assembly comprises a position adjusting assembly positioning assembly connected to the outer sleeve assembly, when the position adjusting assembly positioning assembly is connected to the outer sleeve assembly, the position adjusting assembly positioning assembly can prevent the position adjusting assembly from working, and when the position adjusting assembly positioning assembly slides off from the outer sleeve assembly, the position adjusting assembly positioning assembly can stop the position adjusting assembly from working. And the position adjusting assembly works normally. The displacement switching device is simple to operate and high in stability, can prepare and predict two actions of windowing and drilling, does not form misoperation, and meets the requirements of tests and site construction.

Description

Technical Field

[0001] The present invention relates to the field of oil production in oilfields, and specifically, to a displacement switching device and a working string. Background Art

[0002] At present, as a new production enhancement technology, the hydraulic jet directional drilling technology is increasingly applied in the field of low-permeability oilfield development, such as geological exploration, oil well production enhancement, improving steam injection and water injection effects, etc. Through this technology, the distal fractures of the reservoir or the near-wellbore zone of the wellbore can be directly and effectively communicated to achieve plugging removal, improve the permeability of the production interval, mobilize the remaining oil between wells, and achieve production increase and efficiency improvement.

[0003] The hydraulic jet directional drilling technology is to lower a hydraulic jet directional drilling string into an oil well, apply pressure at the wellhead, first open a window in the casing corresponding to the required specific formation, and then apply pressure again. The drilling mechanism enters the formation through this window position to carry out drilling, thereby forming a long-distance hole in the formation, improving the formation permeability, and further achieving production increase and efficiency improvement. At present, most of the oil wells in oilfields are 5-inch or 5.5-inch. During the process of radially drilling the formation in such a small-diameter casing, we found that after successfully opening a window in the casing at a specific position, there is a displacement difference between the window opening position and the drilling position, and it is difficult or even impossible for the drilling mechanism to pass through this position, thus unable to implement the entire process.

[0004] Specifically, during the process of opening a window and drilling downhole, as Figure 1 shown, restricted by the inner diameter size of the casing c, it is difficult for the drilling mechanism to drill along the radial direction of the casing c. The drilling mechanism can only open a window in the wall of the casing c at a certain inclination angle through the track groove d of the drilling mechanism. After opening the window, drilling is carried out on the formation opposite to the window opening position a. Due to the inclination angle of the track groove d, the movement track b of the drilling mechanism along the track groove d will be in an upper position after entering the formation and cannot pass through the window opening position a smoothly, resulting in the entire hydraulic jet directional drilling technology being unable to be normally implemented.

[0005] Therefore, the applicant provided a technical solution (see CN113445912A). In this technical solution, the lifting height of the central pipe is positioned by injecting pressure into the pipe, and then the positions of the drilling string in the window opening state and the drilling state are adjusted and positioned respectively, compensating for the height difference between the window opening position and the drilling position of the drilling string. However, in the device provided by this technical solution, the initial position of the track ring assembly will change when the pipeline is blocked, and the situation of pipeline blockage cannot be accurately detected, and it is rather cumbersome to count the number of times of pipeline blockage, resulting in the inability to accurately predict the states used for the two actions of window opening and drilling during work and prone to misoperations. Summary of the Invention

[0006] The object of the present invention is to provide a displacement switching device and a working string, the displacement switching device is simple to operate, has high stability, and can prepare for two actions of window opening and drilling, without forming misoperations, meeting the requirements of tests and on-site construction.

[0007] To achieve the above object, in the first aspect of the present invention, a downhole displacement switching device is provided, which is arranged at the bottom of the tubing and is lowered into a predetermined position in the well along with the tubing. The downhole displacement switching device includes a central tube assembly and an outer tube assembly. The outer tube assembly is sleeved outside the central tube assembly. A first accommodation cavity and a second accommodation cavity are formed between the inner wall of the outer tube assembly and the outer wall of the central tube assembly. A position adjustment assembly is arranged in the first accommodation cavity, which can adjust and position the position of the drilling string when it is in the window opening state and the drilling state respectively; the central tube assembly includes a position adjustment assembly positioning component connected to the outer tube assembly, and the position adjustment assembly positioning component can slide off the outer tube assembly under the action of the pressure P1 applied to the outer tube assembly. When the position adjustment assembly positioning component is connected to the outer tube assembly, the position adjustment assembly positioning component can prevent the position adjustment assembly from working. When the position adjustment assembly positioning component slides off the outer tube assembly, the position adjustment assembly works normally; the second accommodation cavity is communicated with the inner cavity of the central tube assembly, and fluid can enter the second accommodation cavity through the inner cavity of the central tube assembly, so as to form a pressure difference inside and outside the device through the entry of the fluid, and the central tube assembly is lifted through this pressure difference. During the process of lifting the central tube assembly, the lifting height of the central tube assembly is positioned by the position adjustment assembly. The lifting height of the drilling string when it is in the drilling state is less than the lifting height of the drilling string when it is in the window opening state, so that the drilling string can be aligned with the window opening position for drilling.

[0008] Optionally, it further includes a pressure application seat assembly, the pressure application seat assembly is connected to the top end of the central tube assembly, and the pressure application seat assembly can slide off the top end of the central tube assembly under the action of the pressure P2 applied to the pressure application seat assembly. The P2 is greater than the P1. When the pressure application seat assembly does not slide off the top end of the central tube assembly, the pressure application seat assembly can prevent external fluid from entering the inner cavity of the central tube assembly from the top end of the central tube assembly, and can make the fluid in the inner cavity of the central tube assembly discharge from the top end of the central tube assembly; when the pressure application seat assembly slides off the top end of the central tube assembly, fluid can enter the inner cavity of the central tube assembly from the pressure application seat assembly.

[0009] Optionally, the pressure application seat assembly includes a pressure application seat and a one-way liquid inlet assembly. A first fluid passage and a second fluid passage are provided on the pressure application seat. The one-way liquid inlet assembly is disposed in the second fluid passage. The fluid in the inner cavity of the central tube assembly is adapted to be discharged from the second fluid passage, and the external fluid is adapted to enter the inner cavity of the central tube assembly from the first fluid passage.

[0010] Optionally, the one-way liquid inlet assembly includes a first one-way damping seal, a second one-way damping seal, a one-way damping spring, and a one-way damping fixing member arranged in sequence. One end of the one-way damping spring abuts against the one-way damping fixing member, and the other end abuts against the second one-way damping seal. When the one-way liquid inlet assembly is not working, the second one-way damping seal abuts against the first one-way damping seal. When the one-way liquid inlet assembly is working, the pressure difference before and after the one-way liquid inlet assembly compresses the one-way damping spring, and a gap for fluid to pass through is formed between the second one-way damping seal and the first one-way damping seal.

[0011] Optionally, the one-way liquid inlet assembly further includes a one-way damping sleeve. One end of the first one-way damping seal abuts against the pressure application seat, and the other end abuts against the one-way damping sleeve, and the one-way damping sleeve is sleeved outside the one-way damping spring.

[0012] Optionally, a connection seal is provided between the one-way damping seal and the pressure application seat.

[0013] Optionally, the central tube assembly includes a central tube inner tube and a central tube outer sleeve sleeved outside the central tube inner tube. The top end of the central tube inner tube is hermetically connected to the central tube outer sleeve, and an opening is formed between the bottom end of the central tube inner tube and the central tube outer sleeve. A third fluid passage adapted for fluid to pass through is formed between the central tube outer sleeve and the central tube inner tube, and a first sand blocking structure is further provided between the central tube outer sleeve and the central tube inner tube.

[0014] Optionally, the first sand blocking structure includes at least two support sand blocking rings I and a sand filtering net I disposed between adjacent support sand blocking rings I.

[0015] Optionally, a filtering structure is provided between the bottom end of the pressure test seat basket and the central tube.

[0016] Optionally, the central tube assembly further includes a pipe string support ring connected to the top end of the central tube.

[0017] Optionally, a second sand blocking structure is provided between the pipe string support ring and the outer sleeve assembly.

[0018] Optionally, the second sand retaining structure includes at least two support sand retaining rings II and a sand filtering net II disposed between adjacent support sand retaining rings II.

[0019] Optionally, a central tube liquid passing hole is provided on the central tube, and the fluid passage communicates with the second accommodating cavity through the liquid passing hole.

[0020] Optionally, a third accommodating cavity is further formed between the inner wall of the outer tube assembly and the outer wall of the central tube assembly. When the volume of the second accommodating cavity increases, the volume of the third accommodating cavity decreases; when the volume of the second accommodating cavity decreases, the volume of the third accommodating cavity increases.

[0021] Optionally, a return spring is disposed in the third accommodating cavity. The return spring is disposed along the axial direction of the central tube assembly. A central tube assembly protrusion is provided on the outer wall of the central tube assembly, and an outer tube assembly protrusion is provided on the inner wall of the outer tube assembly. One end of the return spring abuts against the central tube assembly protrusion, and the other end abuts against the outer tube assembly protrusion.

[0022] Optionally, a breathing hole is provided on the outer tube assembly, and the breathing hole can communicate the third accommodating cavity with the outside.

[0023] Optionally, a breathing hole filter screen is provided in the breathing hole.

[0024] Optionally, the adjusting component positioning component includes an adjusting component positioning ring and a shear ring sleeved on the central tube assembly. One end of the adjusting component positioning ring abuts against the position adjusting component, and the other end abuts against the shear ring. The shear ring is detachably connected to the outer tube assembly.

[0025] Optionally, the position adjustment assembly includes a first track ring, a second track ring, and a track positioning ring; the first track ring and the second track ring are sequentially arranged in the first accommodation cavity from top to bottom. The first track ring and the second track ring are both sleeved on the outside of the central pipe assembly and can slide up and down. The outer walls of the first track ring and the second track ring are both connected to the inner wall of the outer sleeve pipe assembly. The track positioning ring is sleeved on the outside of the central pipe assembly and can rotate circumferentially along the central pipe assembly. The bottom of the first track ring is provided with a first positioning groove and a second positioning groove at intervals along the circumferential direction of the first track ring. The depth of the first positioning groove is greater than that of the second positioning groove. A serrated first track boss is arranged between adjacent first positioning grooves and second positioning grooves. The top of the second track ring is provided with a serrated second track boss that cooperates with the first track boss along the circumferential direction of the second track ring. A spiral slideway is formed along the circumferential direction of the central pipe assembly between the top of the second track boss and the bottom of the first track boss. At least one track nail is arranged on the outer wall of the track positioning ring, and the track nail is arranged between the first track ring and the second track ring; when the drilling pipe string is in a free state, the bottom and the top of the track nail respectively cooperate and abut against the top of the second track boss and the bottom of the first track boss; when the drilling pipe string is in a windowing state, the central pipe assembly is lifted to drive the track positioning ring to slide upward, and the track nail slides along the spiral slideway into the first positioning groove, and the top of the track nail abuts against the inner wall of the top of the first positioning groove; when the drilling pipe string is in a drilling state, the central pipe assembly is lowered to enable the track nail to return to the spiral slideway, and the central pipe assembly is lifted again to drive the track positioning ring to slide upward, and the track nail slides along the spiral slideway into the second positioning groove adjacent to the first positioning groove, and the top of the track nail abuts against the inner wall of the top of the second positioning groove.

[0026] Optionally, the cross-section of the track nail is triangular, and the inner walls of the tops of the first positioning groove and the second positioning groove are both inclined surfaces. The top of the track nail can cooperate and abut against the inner walls of the tops of the first positioning groove and the second positioning groove.

[0027] In a second aspect of the present invention, an operation pipe string is provided. The operation pipe string includes an oil pipe, a drilling pipe string, and the above-mentioned downhole displacement switching device. The top of the downhole displacement switching device is connected to the bottom of the oil pipe, and the bottom of the downhole displacement switching device is connected to the top of the drilling pipe string. The drilling pipe string is lowered into a predetermined drilling position in the well together with the oil pipe and the downhole displacement switching device.

[0028] Through the above technical solution, the downhole displacement switching device provided by the present invention is configured such that the position adjustment component positioning component can slide off the outer casing component under the action of the pressure P1 applied to the outer casing component, and the position adjustment component positioning component is configured to prevent the operation of the position adjustment component when connected to the outer casing component and not affect the operation of the position adjustment component when sliding off the outer casing component. The operation of the position adjustment component can be controlled by the pressure applied to the outer casing component through injection, which is convenient to operate. Moreover, during the process of pipe string encountering resistance, the initial state of the position adjustment component can remain unchanged until it reaches the preset position, so that the two actions of window opening and drilling can be accurately predicted during use, and no misoperation will occur; moreover, it will not affect the normal operation of the position adjustment component.

[0029] An outer casing component is sleeved outside the central pipe component. During use, the top of the outer casing component is connected to the oil pipe, and the bottom of the central pipe component is connected to the drilling pipe string. The drilling pipe string is lowered into a predetermined position in the well through the oil pipe, the outer casing component, and the central pipe component. A position adjustment component is arranged in the first accommodation cavity between the inner wall of the outer casing component and the outer wall of the central pipe component. Pressure is pumped into the oil pipe, and the pressure can sequentially enter the central pipe component through the oil pipe and the outer casing component, so as to control the central pipe component to be lifted through the pressure, and the position adjustment component is used to position the lifting height of the central pipe component, and further adjust and position the positions of the drilling pipe string in the window opening state and the drilling state, so that the lifting height of the drilling pipe string in the drilling state is less than the lifting height of the drilling pipe string in the window opening state, compensating for the height difference between the window opening position and the drilling position of the drilling pipe string, ensuring that the drilling pipe string can be aligned with the window opening position in the drilling state, and greatly improving the drilling operation efficiency. By using the present invention, only the ground pumping pressure needs to be controlled to achieve the displacement switching between downhole casing window opening and formation drilling, with simple operation and high stability, meeting the requirements of tests and on-site construction.

[0030] Other advantages of the present invention and the technical effects of the preferred embodiments will be further described in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0032] Figure 1 is a schematic diagram of the displacement switching principle;

[0033] Figure 2 is a schematic diagram of the initial state structure of the downhole displacement switching device according to an embodiment of the present invention;

[0034] Figure 3 Schematic structural diagram of the downhole displacement switching device in the free state according to an embodiment of the present invention;

[0035] Figure 4 Schematic structural diagram of the downhole displacement switching device in the windowing state according to an embodiment of the present invention;

[0036] Figure 5 Schematic structural diagram of the downhole displacement switching device in the drilling state according to an embodiment of the present invention;

[0037] Figure 6 Schematic structural diagram of the central tube assembly according to a specific embodiment of the present invention;

[0038] Figure 7 Schematic structural diagram of the outer sleeve assembly according to a specific embodiment of the present invention;

[0039] Figure 8 Schematic structural diagram of the pressure application seat assembly according to a specific embodiment of the present invention;

[0040] Figure 9 is Figure 1 partial enlarged schematic diagram;

[0041] Figure 10 Schematic structural diagram of the first trajectory ring according to a specific embodiment of the present invention;

[0042] Figure 11 Schematic structural diagram of the second trajectory ring according to a specific embodiment of the present invention;

[0043] Figure 12 Schematic structural diagram of the trajectory positioning ring according to a specific embodiment of the present invention.

[0044] Explanation of reference numerals

[0045] 1 Lower joint 2 Shearing ring 3 Support sand control ring I 4 Connecting piece I

[0046] 5 Filter screen I 6 Adjusting component positioning ring

[0047] 7 Second trajectory ring fixing piece 8 Second trajectory ring

[0048] 9 Trajectory nail 10 First trajectory ring fixing piece

[0049] 11 First trajectory ring 12 Lower sleeve

[0050] 13 Anti-rotation nail 14 Central tube inner tube

[0051] 15 Upper sleeve 16 Return spring

[0052] 17 Breathing hole 18 Central pipe casing 19 Pipe string support ring 20 Support sand control ring II

[0053] 21 Filter screen II 22 Pressure application seat assembly

[0054] 23 Connector II 24 Upper joint

[0055] 171 Breathing hole nail 172 Breathing hole filter screen

[0056] 181 Central pipe liquid passing hole

[0057] 221 Pressure application seat 222 First one-way damping seal 223 Second one-way damping seal 224 One-way damping spring

[0058] 225 One-way damping sleeve 226 One-way damping fixing part

[0059] 801 Second track boss 901 Track nail

[0060] 1101 First track boss 1102 First positioning groove

[0061] 1103 Second positioning groove Detailed implementation manners

[0062] The following will describe in detail the detailed implementation manners of the present invention with reference to the accompanying drawings. It should be understood that the detailed implementation manners described herein are only for the purpose of illustration and explanation of the present invention, and are not used to limit the present invention.

[0063] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "connected" and "linked" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be an abutting connection, or the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0064] In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features.

[0065] In a basic implementation manner of the present invention, refer to Figure 2, a downhole displacement switching device is provided, which is arranged at the bottom of the tubing and is lowered into a predetermined position in the well along with the tubing. The downhole displacement switching device includes a central tube assembly and an outer tube assembly. The outer tube assembly is sleeved outside the central tube assembly. A first accommodation cavity A and a second accommodation cavity B are formed between the inner wall of the outer tube assembly and the outer wall of the central tube assembly. A position adjustment assembly is arranged in the first accommodation cavity A, which can adjust and position the position of the drilling string when it is in the window-opening state and the drilling state respectively; the central tube assembly includes a position adjustment assembly positioning component connected to the outer tube assembly, and the position adjustment assembly positioning component can slide off the outer tube assembly under the action of the pressure P1 applied to the outer tube assembly. When the position adjustment assembly positioning component is connected to the outer tube assembly, the position adjustment assembly positioning component can prevent the position adjustment assembly from working. When the position adjustment assembly positioning component slides off the outer tube assembly, the position adjustment assembly works normally; the second accommodation cavity B is communicated with the inner cavity of the central tube assembly, and the fluid can enter the second accommodation cavity B through the inner cavity of the central tube assembly, so as to form a pressure difference inside and outside the device through the entry of the fluid, and the central tube assembly is lifted through this pressure difference. During the process of lifting the central tube assembly, the lifting height of the central tube assembly is positioned by the position adjustment assembly. The lifting height of the drilling string when it is in the drilling state is less than the lifting height of the drilling string when it is in the window-opening state, so that the drilling string can be aligned with the window-opening position for drilling.

[0066] According to the present invention, "top", "bottom", "upper", and "lower" refer to the up-and-down positional relationship when the downhole displacement switching device works. Specifically, one end of the downhole displacement switching device connected to the drilling string is the bottom end, and the other end is the top end, which is connected to the tubing; relative to the top end, the bottom end is in the "lower" position, and relative to the bottom end, the top end is in the "upper" position.

[0067] When the downhole displacement switching device provided by the above embodiment of the present invention works, such as Figure 2As shown, the bottom end of the downhole displacement switching device is connected to the drilling string and the connection is sealed, and the top end is connected to the oil pipe. During operation, first lower the downhole displacement switching device into a predetermined position in the well along with the oil pipe. When the downhole displacement switching device moves downward, there is no need to inject fluid into the oil pipe. During this process, the position adjustment assembly always remains in the initial position. When the downhole displacement switching device is lowered to the corresponding position, inject fluid (which can be water, oil or gas) into the downhole displacement switching device through the oil pipe. When the downward pressure formed by the injected fluid on the outer casing assembly is greater than or equal to P1, the positioning component of the position adjustment assembly slides off the outer casing assembly. Continue to inject fluid into the device, and the fluid can enter the second accommodation cavity B through the inner cavity of the central pipe assembly, so as to form a pressure difference inside and outside the device through the entry of the fluid, and realize the lifting of the central pipe assembly through this pressure difference. During the process of lifting the central pipe assembly, the lifting height of the central pipe assembly is positioned through the position adjustment assembly, and then the positions of the drilling string in the window opening state and the drilling state are adjusted and positioned, so that the lifting height of the drilling string in the drilling state is less than the lifting height of the drilling string in the window opening state, compensating for the height difference between the window opening position and the drilling position of the drilling string, ensuring that the drilling string can be aligned with the window opening position in the drilling state, and greatly improving the drilling operation efficiency.

[0068] The downhole displacement switching device provided by the above basic embodiment of the present invention can control the operation of the position adjustment assembly through the pressure applied by the injected fluid on the outer casing assembly, and the operation is convenient. During the process of the pipe string encountering resistance, the initial state of the position adjustment assembly can always remain unchanged before reaching the preset position, so that the two actions of window opening and drilling can be predicted accurately during use without misoperation; moreover, it will not affect the normal operation of the position adjustment assembly.

[0069] An outer casing pipe assembly is sleeved outside the central pipe assembly. During use, the top of the outer casing pipe assembly is connected to the oil pipe, and the bottom of the central pipe assembly is connected to the drilling pipe string. The drilling pipe string is lowered into a predetermined position in the well through the oil pipe, the outer casing pipe assembly and the central pipe assembly. A position adjustment assembly is arranged in the first accommodation cavity A between the inner wall of the outer casing pipe assembly and the outer wall of the central pipe assembly. Pressure is pumped into the oil pipe, and the pressure can sequentially enter the central pipe assembly through the oil pipe and the outer casing pipe assembly, so as to control the lifting of the central pipe assembly through the pressure, and position the lifting height of the central pipe assembly through the position adjustment assembly, and then adjust and position the positions of the drilling pipe string when it is in the window opening state and the drilling state respectively, so that the lifting height of the drilling pipe string when it is in the drilling state is less than the lifting height of the drilling pipe string when it is in the window opening state, compensating for the height difference between the window opening position and the drilling position of the drilling pipe string, ensuring that the drilling pipe string can be aligned with the window opening position when it is in the drilling state, and greatly improving the drilling operation efficiency. By adopting the present invention, only the ground pumping pressure needs to be controlled to realize the displacement switching between downhole casing window opening and formation drilling, and the operation is simple and the stability is high, meeting the requirements of tests and on-site construction.

[0070] In a specific embodiment of the present invention, the central pipe assembly and the outer casing pipe assembly are connected by a breakable connecting member (hereinafter denoted as connecting member I 4), and the connecting member I 4 can break when the pressure applied thereto is greater than or equal to the first preset pressure P1. The connecting member I 4 can be any connecting member that can achieve the above effects. Exemplarily, the connecting member I 4 is a shear screw.

[0071] In a specific embodiment of the present invention, the device further includes a pressure application seat assembly 22. The pressure application seat assembly 22 is connected to the top end of the central pipe assembly, and the pressure application seat assembly 22 can slide off the top end of the central pipe assembly under the action of the pressure P2 applied to the pressure application seat assembly 22. P2 is greater than P1. When the pressure application seat assembly 22 does not slide off the top end of the central pipe assembly, the pressure application seat assembly 22 can prevent external fluid from entering the inner cavity of the central pipe assembly from the top end of the central pipe assembly, and can discharge the fluid in the inner cavity of the central pipe assembly from the top end of the central pipe assembly; when the pressure application seat assembly 22 slides off the top end of the central pipe assembly, the fluid can enter the inner cavity of the central pipe assembly from the pressure application seat assembly 22. The pressure application seat assembly 22 can slide off the top end of the central pipe assembly under the action of the pressure P2 applied to the pressure application seat assembly 22, and setting P2 to be greater than P1 can further reduce the influence of encountering resistance during the process of entering the well, and can discharge the fluid (which can be water, oil or gas) in the inner cavity of the central pipe assembly from the top end of the central pipe assembly, reducing the downhole resistance caused by the well pressure, and preventing the large pressure difference between the inside of the downhole displacement switching device and the well from making it difficult for the device to enter the well. After sliding off, the liquid can be smoothly injected into the inner cavity of the central pipe assembly, ensuring the normal operation of the downhole displacement switching device and being convenient to operate.

[0072] As a specific embodiment of the present invention, the pressure application seat assembly 22 and the central tube assembly can be connected by a breakable connecting member (hereinafter referred to as connecting member II 23), and the connecting member II 23 can break when the pressure applied thereto is greater than or equal to the second preset pressure P2. The connecting member II 23 can be any connecting member that can achieve the above effects. Exemplarily, the connecting member II 23 is a shear screw.

[0073] In the present invention, the pressure application seat assembly 22 and / or the outer sleeve assembly are pressurized by injecting fluid into the device from the top.

[0074] According to the present invention, the first preset pressure and the second preset pressure can be determined according to the actual situation. As a specific embodiment of the present invention, the first preset pressure can be set to 3-4 MPa, and the second preset pressure can be set to 6-8 MPa.

[0075] In a specific embodiment of the present invention, the method for the pressure application seat assembly 22 to slide off from the top end of the central tube assembly under the action of the pressure applied to the pressure application seat assembly 22 includes: when the pressure applied to the pressure application seat assembly 22 is less than the preset pressure P2, the pressure application seat assembly 22 is connected to the top end of the central tube assembly; when the pressure applied to the pressure application seat assembly 22 is greater than or equal to the preset pressure P2, the pressure application seat assembly 22 slides off.

[0076] In a specific embodiment of the present invention, the pressure application seat assembly 22 includes a pressure application seat 221 and a one-way liquid inlet assembly. A first fluid passage C and a second fluid passage D are provided on the pressure application seat 221. The one-way liquid inlet assembly is arranged in the second fluid passage D. The fluid in the inner cavity of the central tube assembly is adapted to be discharged from the second fluid passage D, and the external fluid is adapted to enter the inner cavity of the central tube assembly from the first fluid passage C. The settings of the first fluid passage C and the second fluid passage D can prevent the mutual influence of the fluids during the flow process, and further facilitate the discharge and introduction of the fluids.

[0077] A first fluid passage C and a second fluid passage D are provided on the pressure application seat assembly 22. The outlet of the first fluid passage C communicates with the inner cavity of the central tube assembly, the inlet of the second fluid passage D communicates with the inner cavity of the central tube assembly, and the outlet of the second fluid passage D communicates with the oil pipe. When the pressure application seat assembly 22 is connected to the top end of the central tube assembly, the central tube assembly can block the inlet of the first fluid passage C. At this time, when the pressure in the inner cavity of the central tube assembly is greater than the external pressure, the fluid in the inner cavity of the central tube assembly can pass through the one-way liquid inlet assembly and be discharged from the second fluid passage D. When the pressure in the inner cavity of the central tube assembly is less than the external pressure, due to the blocking of the one-way liquid inlet assembly, the fluid outside the central tube assembly cannot enter the inner cavity of the central tube assembly from the second fluid passage D; when the pressure application seat assembly 22 slides off the top end of the central tube assembly, the fluid in the oil pipe can enter the inner cavity of the central tube assembly from the first fluid passage C.

[0078] In a specific embodiment of the present invention, the one-way liquid inlet assembly includes a first one-way damping seal 222, a second one-way damping seal 223, a one-way damping spring 224, and a one-way damping fixing member 226 arranged in sequence. One end of the one-way damping spring 224 abuts against the one-way damping fixing member 226, and the other end abuts against the second one-way damping seal 223. When the one-way liquid inlet assembly is not working, the second one-way damping seal 223 abuts against the first one-way damping seal 222. When the one-way liquid inlet assembly is working, the pressure difference before and after the one-way liquid inlet assembly compresses the one-way damping spring 224, and a gap for the fluid to pass through is formed between the second one-way damping seal 223 and the first one-way damping seal 222. By adopting the above one-way liquid inlet assembly, the structure is simple, and the purpose of one-way liquid inlet can be achieved.

[0079] According to the present invention, the first one-way damping seal 222 is arranged near the inlet of the second fluid passage D, and the one-way damping fixing member 226 is arranged near the outlet of the second fluid passage D. When the pressure in the inner cavity of the central tube assembly is less than or equal to the pressure in the oil pipe, the second one-way damping seal 223 abuts against the first one-way damping seal 222; when the pressure in the inner cavity of the central tube assembly is greater than the pressure in the oil pipe, the pressure difference will cause the one-way damping spring 224 to compress. During this process, a gap for the fluid to pass through is formed between the second one-way damping seal 223 and the first one-way damping seal 222.

[0080] According to the present invention, the one-way damping fixing member 226 can be a joint, which can be threadedly connected to the pressure application seat 221. The one-way damping spring 224 is sleeved on the joint, and breathing holes are evenly arranged circumferentially at the end of the joint. The arrangement of the joint can enable the one-way damping spring 224 to compress and rebound along a preset position.

[0081] Among them, "front" refers to the direction in which the fluid flows, and "rear" refers to the opposite direction.

[0082] As a specific embodiment of the present invention, the one-way liquid inlet assembly includes a first one-way damping seal 222, a second one-way damping seal 223, a one-way damping spring 224, a one-way damping fixing member 226 and a one-way damping sleeve 225. The first one-way damping seal 222, the second one-way damping seal 223, the one-way damping spring 224 and the one-way damping fixing member 226 are arranged along the fluid flow direction. One end of the first one-way damping seal 222 abuts against the pressure seat 221, and the other end abuts against the one-way damping sleeve 225. The one-way damping sleeve 225 is sleeved outside the one-way damping spring 224. One end of the one-way damping spring 224 abuts against the one-way damping fixing member 226, and the other end abuts against the second one-way damping seal 223. When the one-way liquid inlet assembly is not working, the second one-way damping seal 223 abuts against the first one-way damping seal 222. When the one-way liquid inlet assembly is working, the pressure difference before and after the one-way liquid inlet assembly compresses the one-way damping spring 224, and a gap for fluid to pass through is formed between the second one-way damping seal 223 and the first one-way damping seal 222. The setting of the one-way damping sleeve 225 can protect the one-way damping spring 224.

[0083] In a specific embodiment of the present invention, a connecting seal is provided between the one-way damping seal 222 and the pressure seat 221. The setting of the connecting seal can prevent fluid from passing between the one-way damping seal 222 and the pressure seat 221 and ensure the sealing performance between the two. The connecting seal can be any structure that can achieve a sealing effect. As a specific embodiment of the present invention, the connecting seal is an O-ring seal.

[0084] In a specific embodiment of the present invention, the central tube assembly includes a central tube inner tube 14 and a central tube outer sleeve 18 sleeved outside the central tube inner tube 14. The top end of the central tube inner tube 14 is hermetically connected to the central tube outer sleeve 18, and an opening is formed between the bottom end of the central tube inner tube 14 and the central tube outer sleeve 18. A third fluid passage F suitable for fluid to pass through is formed between the central tube outer sleeve 18 and the central tube inner tube 14, and a first sand blocking structure is further provided between the central tube outer sleeve 18 and the central tube inner tube 14. Through the setting of the first sand blocking structure, it is possible to prevent the sand and gravel in the inner cavity of the central tube inner tube 14 from entering the second accommodating cavity B, and while ensuring the normal operation of the device, the service life of the device can be extended.

[0085] According to the present invention, the central tube inner tube 14 can be a pressure test seat basket.

[0086] The first sand control structure can be any structure that can achieve the sand control effect. As a specific embodiment of the present invention, the first sand control structure includes at least two support sand control rings I 3 and a sand filtering net I 5 disposed between adjacent support sand control rings I 3. The setting of the support sand control rings I 3 can support the inner pipe 14 of the central pipe and the central pipe casing 18, and can achieve the effect of sand filtering; the setting of the sand filtering net I 5 can further improve the sand filtering effect.

[0087] In a specific embodiment of the present invention, the central pipe assembly includes an inner pipe 14 of the central pipe and a central pipe casing 18 sleeved outside the inner pipe 14 of the central pipe. The top end of the inner pipe 14 of the central pipe is hermetically connected to the central pipe casing 18, and an opening is formed between the bottom end of the inner pipe 14 of the central pipe and the central pipe casing 18. A third fluid passage F suitable for fluid to pass through is formed between the central pipe casing 18 and the inner pipe 14 of the central pipe, and a first sand control structure is further provided between the central pipe casing 18 and the inner pipe 14 of the central pipe. A filtering structure is provided between the bottom end of the inner pipe 14 of the central pipe and the central pipe casing 18. The setting of the filtering structure can preliminarily filter the fluid entering the third fluid passage F, filter out large impurities, and then filter again through the first sand control structure to filter out small gravel, which can prevent impurities in the inner cavity of the inner pipe 14 of the central pipe from entering the second accommodating cavity B, and further extend the service life of the device while ensuring the normal operation of the device.

[0088] In a specific embodiment of the present invention, the central pipe assembly includes an inner pipe 14 of the central pipe, a central pipe casing 18 sleeved outside the inner pipe 14 of the central pipe, and a pipe string support ring 19 connected to the top end of the central pipe casing 18. The pressure application seat assembly 22 is connected to the pipe string support ring 19. The top end of the inner pipe 14 of the central pipe is hermetically connected to the central pipe casing 18, and an opening is formed between the bottom end of the inner pipe 14 of the central pipe and the central pipe casing 18. A third fluid passage F suitable for fluid to pass through is formed between the central pipe casing 18 and the inner pipe 14 of the central pipe. Through the setting of the pipe string support ring 19, it can not only be used to fix the pressure application seat assembly 22, but also seal the top end of the inner pipe 14 of the central pipe and the central pipe casing 18, without the need to additionally set up a structure, which is simple and convenient.

[0089] Specifically, the pipe string support ring 19 is threadedly connected to the central pipe casing 18, and the pipe string support ring 19 is clamped with the inner pipe 14 of the central pipe. The inner pipe 14 of the central pipe, the pipe string support ring 19 and the central pipe casing 18 are hermetically connected. A boss structure for preventing the pressure application seat assembly 22 from continuing to fall is further provided on the inner pipe 14 of the central pipe.

[0090] In a specific embodiment of the present invention, the central tube assembly includes a central tube inner tube 14, a central tube outer sleeve 18 sleeved outside the central tube inner tube 14, and a pipe string support ring 19 connected to the top end of the central tube outer sleeve 18. The pressure application seat assembly 22 is connected to the pipe string support ring 19. The top end of the central tube inner tube 14 is hermetically connected to the central tube outer sleeve 18. An opening is formed between the bottom end of the central tube inner tube 14 and the central tube outer sleeve 18. A third fluid passage F suitable for fluid passage is formed between the central tube outer sleeve 18 and the central tube inner tube 14. A second sand blocking structure is provided between the pipe string support ring 19 and the outer sleeve assembly. The setting of the second sand blocking structure can prevent impurities from entering between the central tube assembly and the outer sleeve assembly, further extending the service life of the device while ensuring the normal operation of the device.

[0091] The second sand blocking structure can be any structure that can achieve the sand blocking effect. As a specific embodiment of the present invention, the second sand blocking structure includes at least two support sand blocking rings II 20 and a sand filtering net II 21 arranged between adjacent support sand blocking rings II 20. The setting of the support sand blocking rings II 20 can center the central tube assembly and the outer sleeve assembly and achieve the effect of sand filtering; the setting of the sand filtering net II 21 can further improve the sand filtering effect.

[0092] In a specific embodiment of the present invention, the pipe string support ring 19 includes a first pipe string support part, a second pipe string support part, and a third pipe string support part arranged in sequence. The inner wall surface of the first pipe string support part is threadedly connected to the outer wall surface of the second pipe string support part. An included angle is formed between the outer wall surface of the first pipe string support part and the outer wall surface of the second pipe string support part, and this included angle faces the central tube inner tube 14 and is an obtuse angle. The setting of the obtuse angle can reduce the water flow impact. And one end of the first pipe string support part that is not connected to the second pipe string support part is provided with a chamfer to reduce the impact on the outer sleeve assembly during the working process and extend the service life of the device.

[0093] In a specific embodiment of the present invention, the central tube outer sleeve 18 is provided with a central tube liquid passing hole 181, and the fluid passage is communicated with the second accommodation cavity B through the central tube liquid passing hole 181.

[0094] In a specific embodiment of the present invention, a third accommodation cavity E that cooperates with the second accommodation cavity B is further formed between the inner wall of the outer sleeve assembly and the outer wall of the central tube assembly. When the volume of the second accommodation cavity B increases, the volume of the third accommodation cavity E decreases; when the volume of the second accommodation cavity B decreases, the volume of the third accommodation cavity E increases.

[0095] In a specific embodiment of the present invention, a third accommodating cavity E that cooperates with the second accommodating cavity B is further formed between the inner wall of the outer sleeve assembly and the outer wall of the central tube assembly. When the volume of the second accommodating cavity B increases, the volume of the third accommodating cavity E decreases; when the volume of the second accommodating cavity B decreases, the volume of the third accommodating cavity E increases. A return spring 16 is arranged in the third accommodating cavity E. The return spring 16 is arranged along the axial direction of the central tube assembly. A central tube assembly protrusion is arranged on the outer wall of the central tube assembly, and an outer sleeve assembly protrusion is arranged on the inner wall of the outer sleeve assembly. One end of the return spring 16 abuts against the central tube assembly protrusion, and the other end abuts against the outer sleeve assembly protrusion. The arrangement of the return spring 16 can further facilitate the reset of the central tube assembly.

[0096] In a specific embodiment of the present invention, a breathing hole 17 is provided on the outer sleeve assembly. The breathing hole can communicate the third accommodating cavity E with the outside of the device. The arrangement of the breathing hole 17 can achieve the purpose of pressure relief and facilitate the relative movement of the central tube assembly and the outer sleeve assembly.

[0097] As a specific embodiment of the present invention, a breathing hole 17 is provided on the outer sleeve assembly. The breathing hole can communicate the third accommodating cavity E with the outside of the device, and a breathing hole filter screen 172 is arranged in the breathing hole 17. The arrangement of the breathing hole filter screen 172 can prevent impurities outside the device from entering the third accommodating cavity E and ensure the normal pressure regulating function of the third accommodating cavity E.

[0098] According to the present invention, the breathing hole filter screen 172 can be connected to the outer sleeve assembly through a breathing hole nail 171.

[0099] In a specific embodiment of the present invention, the downhole displacement switching device includes a central tube assembly and an outer tube assembly. The outer tube assembly is sleeved outside the central tube assembly. A first accommodation cavity A and a second accommodation cavity B are formed between the inner wall of the outer tube assembly and the outer wall of the central tube assembly. A position adjustment assembly is arranged in the first accommodation cavity A, which can adjust and position the position of the drilling string when it is in the window-opening state and the drilling state respectively; the central tube assembly includes a position adjustment assembly positioning component. The adjustment assembly positioning component includes an adjustment assembly positioning ring 6 and a shear ring 2 sleeved on the central tube assembly. One end of the adjustment assembly positioning ring 6 abuts against the position adjustment assembly, and the other end abuts against the shear ring 2. The shear ring 2 is detachably connected to the outer tube assembly, and the shear ring 2 can slide off the outer tube assembly under the action of the pressure P1 applied to the outer tube assembly. When the shear ring 2 is connected to the outer tube assembly, the adjustment assembly positioning ring 6 can prevent the position adjustment assembly from working. When the shear ring 2 slides off the outer tube assembly, a gap is formed between the adjustment assembly positioning ring 6 and the position adjustment assembly, and the position adjustment assembly can work normally; the second accommodation cavity B is communicated with the inner cavity of the central tube assembly, and fluid can enter the second accommodation cavity B through the inner cavity of the central tube assembly, so as to form a pressure difference inside and outside the device through the entry of the fluid, and the central tube assembly is lifted through this pressure difference. During the process of lifting the central tube assembly, the lifting height of the central tube assembly is positioned by the position adjustment assembly. The lifting height of the drilling string when it is in the drilling state is less than the lifting height of the drilling string when it is in the window-opening state, so that the drilling string can be aligned with the window-opening position for drilling. Specifically, the shear ring 2 can be connected to the outer tube assembly through the connecting piece I 4.

[0100] The downhole displacement switching device provided by the above embodiment has a simple structure, can control the operation of the position adjustment assembly by injecting the pressure applied to the outer tube assembly, and is easy to operate. During the process of the pipe string encountering resistance, the initial state of the position adjustment assembly can remain unchanged before reaching the preset position, so that the two actions of window-opening and drilling can be predicted accurately during use, and no misoperation will occur; moreover, it will not affect the normal operation of the position adjustment assembly.

[0101] In a specific embodiment of the present invention, the position adjustment assembly includes a first track ring 11, a second track ring 8, and a track positioning ring 9; the first track ring 11 and the second track ring 8 are sequentially arranged in the first accommodation cavity from top to bottom. The first track ring 11 and the second track ring 8 are both sleeved on the outside of the central pipe assembly and can slide up and down. The outer walls of the first track ring 11 and the second track ring 8 are both connected to the inner wall of the outer sleeve pipe assembly. The track positioning ring 9 is sleeved on the outside of the central pipe assembly and can rotate circumferentially along the central pipe assembly. The bottom of the first track ring 11 is provided with a first positioning groove 1102 and a second positioning groove 1103 at intervals along the circumference of the first track ring 11. The depth of the first positioning groove 1102 is greater than the depth of the second positioning groove 1103. A serrated first track boss 1101 is provided between each adjacent first positioning groove 1102 and the second positioning groove 1103. The top of the second track ring 8 is provided with a serrated second track boss 801 that cooperates with the first track boss 1101 along the circumference of the second track ring 8. A spiral chute is formed along the circumference of the central pipe assembly between the top of the second track boss 801 and the bottom of the first track boss 1101. At least one track nail 901 is provided on the outer wall of the track positioning ring 9. The track nail 901 is arranged between the first track ring 11 and the second track ring; when the drilling string is in a free state, the bottom and the top of the track nail 901 respectively cooperate with and abut against the top of the second track boss 801 and the bottom of the first track boss 1101; when the drilling string is in a windowing state, by lifting the central pipe assembly to drive the track positioning ring 9 to slide upward. Since the track nail 901 is located between the top of the second track boss 801 and the bottom of the first track boss 1101, the track nail 901 slides along the spiral chute (i.e., while the track positioning ring 9 slides upward, it rotates circumferentially along the central pipe assembly) into the first positioning groove 1102. The top of the track nail 901 abuts against the inner wall of the top of the first positioning groove 1102. The position of the central pipe assembly and the outer sleeve pipe assembly in the windowing state is positioned through the cooperation of the first positioning groove 1102 and the track nail 901, so as to position the lifting height of the drilling string in the windowing state;When the drilling string is in the drilling state, lower the central pipe assembly so that the track pin 901 returns to the spiral chute. By lifting the central pipe assembly again, drive the track positioning ring 9 to slide upward. The track pin 901 slides along the spiral chute into the second positioning groove 1103 adjacent to the first positioning groove 1102. The top of the track pin 901 abuts against the top inner wall of the second positioning groove 1103. The position of the central pipe assembly and the outer sleeve assembly in the drilling state is positioned through the cooperation of the second positioning groove 1103 and the track pin 901, so as to position the lifting height of the drilling string in the drilling state. Since the depth of the first positioning groove 1102 is greater than the depth of the second positioning groove 1103, the lifting height of the drilling string in the drilling state is less than the lifting height of the drilling string in the windowing state, thereby compensating for the height difference between the windowing position and the drilling position of the drilling string and ensuring that the drilling string can be aligned with the windowing position in the drilling state.;

[0102] According to the present invention, the second track ring 8 can be fixed to the outer sleeve assembly through the second track ring fixing member 7, and the first track ring 11 can be fixed to the outer sleeve assembly through the first track ring fixing member 10. Exemplarily, the second track ring fixing member 7 and the first track ring fixing member 10 can be set screws.

[0103] The number of track pins 901 is multiple. The number of track pins 901, the number of first positioning grooves 1102, and the number of second positioning grooves 1103 are the same. Each track pin 901 is evenly distributed along the circumferential direction of the track positioning ring 9. The cross-section of each track pin 901 is triangular. The top inner walls of the first positioning groove 1102 and the second positioning groove 1103 are both inclined surfaces. The top of the track pin 901 can cooperate with and abut against the top inner walls of the first positioning groove 1102 and the second positioning groove 1103, so as to ensure stable connection when the outer sleeve and the central pipe assembly are in different connection positions in both the windowing state and the drilling state.

[0104] The depths of the first positioning groove 1102 and the second positioning groove 1103 can be determined by those skilled in the art according to the actual situation. As a specific embodiment of the present invention, the depth range of the first positioning groove 1102 is 10 mm to 30 mm, the depth range of the second positioning groove 1103 is 40 mm to 60 mm, and the difference between the depth of the first positioning groove 1102 and the depth of the second positioning groove 1103 is 20 mm to 30 mm, so that the drilling string can be aligned with the windowing position in the drilling state and ensure the smooth progress of the drilling operation.

[0105] In a specific embodiment of the present invention, such as Figure 2As shown in the figure, the outer sleeve assembly includes an upper sleeve 15 and a lower sleeve 12. Both the upper sleeve 15 and the lower sleeve 12 are cylindrical structures with openings at the top and bottom along the vertical direction. The bottom of the upper sleeve 15 is threadedly connected to the top of the lower sleeve 12. The first accommodation cavity A is located between the inner wall of the lower part of the lower sleeve 12 and the outer wall of the central tube assembly, and the second accommodation cavity B is located between the upper sleeve 15 and the lower sleeve 12.

[0106] In a specific embodiment of the present invention, as Figure 2 shown, at least one elongated chute is axially formed on the outer wall of the central tube assembly along the axis of the central tube assembly. An anti-rotation nail 13 is provided at a position on the lower sleeve 12 opposite to the chute 202. One end of the anti-rotation nail 13 is connected to the inner wall of the lower sleeve 12, and the other end of the anti-rotation nail 13 can slidably fit into the chute. Through the cooperation of the chute and the anti-rotation nail 13, the lower sleeve 12 and the upper sleeve 15 are limited in the circumferential direction thereof, ensuring that the lower sleeve 12 and the upper sleeve 15 can only slide relative to the central tube assembly in the vertical direction, and preventing the lower sleeve 12 and the upper sleeve 15 from rotating along the circumference of the central tube assembly.

[0107] As a specific embodiment of the present invention, as Figure 2 shown, a seal is provided at the connection between the inner wall of the upper sleeve 15 and the central tube assembly, and a sealing ring is also provided at the connection between the inner wall of the lower sleeve 12 and the central tube assembly. Through the setting of the sealing ring, a good sealing effect of the second accommodation cavity B is ensured.

[0108] In an alternative embodiment of the present invention, as Figure 2 shown, the central tube assembly further includes a lower joint 1. The lower joint 1 is a cylindrical structure arranged along the vertical direction. The inner wall of the top of the lower joint 1 is threadedly connected to the outer wall of the bottom of the central tube casing 18, and the outer wall of the bottom of the lower joint 1 is threadedly connected to the inner wall of the top of the drilling string. Through the setting of the lower joint 1, the connection and disassembly between the central tube casing 18 and the drilling string are facilitated, which is convenient for on-site construction operations.

[0109] The outer sleeve assembly further includes an upper joint 24. The upper joint is a cylindrical structure arranged along the vertical direction. The outer wall of the bottom end of the upper joint 24 is threadedly connected to the inner wall of the upper sleeve 15, and the outer wall of the top of the upper joint 24 is connected to the oil pipe. Through the setting of the upper joint 24, the connection and disassembly between the outer sleeve assembly and the oil pipe are facilitated, which is convenient for on-site construction operations.

[0110] As a relatively preferred specific embodiment of the present invention, refer to Figures 1 - 12, the downhole displacement switching device includes a central pipe assembly, an outer sleeve pipe assembly, and a pressure application seat assembly 22. The outer sleeve pipe assembly is sleeved outside the central pipe assembly. A first accommodation cavity A and a second accommodation cavity B are formed between the inner wall of the outer sleeve pipe assembly and the outer wall of the central pipe assembly. A position adjustment assembly is arranged in the first accommodation cavity A, which can adjust and position the position of the drilling pipe string when it is in the windowing state and the drilling state respectively; the central pipe assembly includes a position adjustment assembly positioning component connected to the outer sleeve pipe assembly. The adjustment component positioning component includes an adjustment component positioning ring 6 and a shear ring 2 sleeved on the central pipe assembly. One end of the adjustment component positioning ring 6 abuts against the position adjustment assembly, and the other end abuts against the shear ring 2. The shear ring 2 is detachably connected to the outer sleeve pipe assembly, and the shear ring 2 can slide off the outer sleeve pipe assembly under the action of the pressure P1 applied to the outer sleeve pipe assembly. When the shear ring 2 is connected to the outer sleeve pipe assembly, the adjustment component positioning ring 6 can prevent the position adjustment assembly from working. When the shear ring 2 slides off the outer sleeve pipe assembly, a gap is formed between the adjustment component positioning ring 6 and the position adjustment assembly, and the position adjustment assembly can work normally; the pressure application seat assembly 22 is connected to the top of the central pipe assembly, and the pressure application seat assembly 22 can slide off the top of the central pipe assembly under the action of the pressure P2 applied to the pressure application seat assembly 22. P2 is greater than P1. When the pressure application seat assembly 22 does not slide off the top of the central pipe assembly, the pressure application seat assembly 22 can prevent external fluid from entering the inner cavity of the central pipe assembly from the top of the central pipe assembly, and can discharge the fluid in the inner cavity of the central pipe assembly from the top of the central pipe assembly; the pressure application seat assembly 22 includes a pressure application seat 221 and a one-way liquid inlet assembly. A first fluid channel C and a second fluid channel D are arranged on the pressure application seat 221. The one-way liquid inlet assembly is arranged in the second fluid channel D. The fluid in the inner cavity of the central pipe assembly is suitable for being discharged from the second fluid channel D, and the external fluid is suitable for entering the inner cavity of the central pipe assembly from the first fluid channel C; the one-way liquid inlet assembly includes a first one-way damping seal 222, a second one-way damping seal 223, a one-way damping spring 224, a one-way damping fixing part 226, and a one-way damping sleeve 225. The first one-way damping seal 222, the second one-way damping seal 223, the one-way damping spring 224, and the one-way damping fixing part 226 are arranged along the fluid flow direction. One end of the first one-way damping seal 222 abuts against the pressure application seat 221, and the other end abuts against the one-way damping sleeve 225. The one-way damping sleeve 225 is sleeved outside the one-way damping spring 224; one end of the one-way damping spring 224 abuts against the one-way damping fixing part 226, and the other end abuts against the second one-way damping seal 223. When the one-way liquid inlet assembly is not working, the second one-way damping seal 223 abuts against the first one-way damping seal 222. When the one-way liquid inlet assembly is working, the pressure difference before and after the one-way liquid inlet assembly compresses the one-way damping spring 224, and a gap for fluid to pass through is formed between the second one-way damping seal 223 and the first one-way damping seal 222;When the pressure application seat assembly 22 slides down from the top end of the central pipe assembly, fluid can enter the inner cavity of the central pipe assembly from the pressure application seat assembly 22 and enter the second accommodation cavity B through the inner cavity of the central pipe assembly, so as to form a pressure difference inside and outside the device through the entry of the fluid, and lift the central pipe assembly through this pressure difference. The position adjustment assembly includes a first track ring 11, a second track ring 8 and a track positioning ring 9; the first track ring 11 and the second track ring 8 are sequentially arranged in the first accommodation cavity from top to bottom. Both the first track ring 11 and the second track ring 8 are slidably sleeved on the outside of the central pipe assembly, and the outer walls of the first track ring 11 and the second track ring 8 are both connected to the inner wall of the outer sleeve pipe assembly. The track positioning ring 9 is rotatably sleeved on the outside of the central pipe assembly along the circumferential direction of the central pipe assembly. The bottom of the first track ring 11 is provided with a first positioning groove 1102 and a second positioning groove 1103 at intervals along the circumferential direction of the first track ring 11. The depth of the first positioning groove 1102 is greater than the depth of the second positioning groove 1103. A serrated first track boss 1101 is arranged between adjacent first positioning grooves 1102 and second positioning grooves 1103. The top of the second track ring 8 is provided with a serrated second track boss 801 that cooperates with the first track boss 1101 along the circumferential direction of the second track ring 8. A spiral slideway is formed along the circumferential direction of the central pipe assembly between the top of the second track boss 801 and the bottom of the first track boss 1101. At least one track nail 901 is arranged on the outer wall of the track positioning ring 9. The track nail 901 is arranged between the first track ring 11 and the second track ring; when the drilling string is in a free state, the bottom and top of the track nail 901 respectively cooperate with and abut against the top of the second track boss 801 and the bottom of the first track boss 1101; when the drilling string is in a windowing state, by lifting the central pipe assembly to drive the track positioning ring 9 to slide upward, since the track nail 901 is located between the top of the second track boss 801 and the bottom of the first track boss 1101, the track nail 901 slides along the spiral slideway (that is: while the track positioning ring 9 slides upward, it rotates along the circumferential direction of the central pipe assembly) into the first positioning groove 1102, and the top of the track nail 901 abuts against the inner wall of the top of the first positioning groove 1102. The position of the central pipe assembly and the outer sleeve pipe assembly in the windowing state is positioned through the cooperation of the first positioning groove 1102 and the track nail 901, so as to position the lifting height of the drilling string in the windowing state;When the drilling string is in the drilling state, lower the central pipe assembly so that the track pin 901 returns to the spiral chute. By lifting the central pipe assembly again, drive the track positioning ring 9 to slide upward. The track pin 901 slides along the spiral chute into the second positioning groove 1103 adjacent to the first positioning groove 1102. The top of the track pin 901 abuts against the inner wall of the top of the second positioning groove 1103. The position of the central pipe assembly and the outer sleeve pipe assembly in the drilling state is positioned through the cooperation of the second positioning groove 1103 and the track pin 901, so as to position the lifting height of the drilling string in the drilling state. The lifting height of the drilling string in the drilling state is less than the lifting height of the drilling string in the window opening state, compensating for the height difference between the window opening position and the drilling position of the drilling string, ensuring that the drilling string can be aligned with the window opening position in the drilling state; The central pipe assembly includes a central pipe inner pipe 14, a central pipe sleeve 18 sleeved outside the central pipe inner pipe 14, and a pipe string support ring 19 connected to the top of the central pipe sleeve 18. The pressure seat assembly 22 is connected to the pipe string support ring 19. The top of the central pipe inner pipe 14 is hermetically connected to the central pipe sleeve 18. An opening is formed between the bottom end of the central pipe inner pipe 14 and the central pipe sleeve 18. A third fluid passage F suitable for fluid to pass through is formed between the central pipe sleeve 18 and the central pipe inner pipe 14. And a first sand blocking structure is also arranged between the central pipe sleeve 18 and the central pipe inner pipe 14. A filtering structure is arranged between the bottom end of the central pipe inner pipe 14 and the central pipe sleeve 18. A second sand blocking structure is arranged between the pipe string support ring 19 and the outer sleeve pipe assembly; The first sand blocking structure includes at least two support sand blocking rings I 3 and a sand filtering net I 5 arranged between adjacent support sand blocking rings I 3. The second sand blocking structure includes at least two support sand blocking rings II 20 and a sand filtering net II 21 arranged between adjacent support sand blocking rings II 20. The pipe string support ring 19 includes a first pipe string support part, a second pipe string support part and a third pipe string support part arranged in sequence. The inner wall surface of the first pipe string support part is threadedly connected to the outer wall surface of the second pipe string support part. An included angle is formed between the outer wall surface of the first pipe string support part and the outer wall surface of the second pipe string support part, and this included angle faces the central pipe inner pipe 14, and this included angle is an obtuse angle. A central pipe liquid passing hole 181 is arranged on the central pipe sleeve 18. The fluid passage is communicated with the second accommodating cavity B through the central pipe liquid passing hole 181. A third accommodating cavity E matching with the second accommodating cavity B is also formed between the inner wall of the outer sleeve pipe assembly and the outer wall of the central pipe assembly. When the volume of the second accommodating cavity B increases, the volume of the third accommodating cavity E decreases;When the volume of the second accommodating cavity B decreases, the volume of the third accommodating cavity E increases. A return spring 16 is arranged in the third accommodating cavity E. The return spring 16 is arranged along the axial direction of the central tube assembly. A protrusion of the central tube assembly is arranged on the outer wall of the central tube assembly, and a protrusion of the outer sleeve assembly is arranged on the inner wall of the outer sleeve assembly. One end of the return spring 16 abuts against the protrusion of the central tube assembly, and the other end abuts against the protrusion of the outer sleeve assembly. A breathing hole 17 is arranged on the outer sleeve assembly. The breathing hole can communicate the third accommodating cavity E with the outside of the device. A breathing hole filter screen 172 is arranged in the breathing hole 17.;

[0111] According to the present invention, L1: the distance from the lower part of the pipe string support ring 19 to the inner step of the upper sleeve 15 in the initial state, L2: the distance from the first positioning groove 1102 to the second track ring 8, L3: the distance from the second positioning groove 1103 to the second track ring 8, L4: the length of the anti-rotation nail track groove on the central tube casing 18, L5: the distance from the inner seal ring groove inside the lower sleeve 12 to the reduced diameter part (i.e., the non-sealing surface) of the central tube casing 18 in the free state

[0112] As Figure 2 As shown in the figure, the lower end of the downhole displacement switching device is connected and sealed with the hydraulic jet radial drilling pipe string by the left end of the lower joint 1 using tubing threads. The right end of the lower joint 1 is connected and sealed with the central tube casing 18 using tubing threads. The central tube casing 18 has multiple steps with different diameters. There is an anti-rotation nail groove on the outer diameter surface of the side for the axial sliding of the anti-rotation nail 13. A central tube liquid passing hole 181 for the liquid flow is drilled radially. The right end of the central tube casing 18 is threadedly connected with the pipe string support ring 19 and sealed with an O-ring. Screw holes are circumferentially arranged at the upper end of the pipe string support ring 19. The pressure application seat assembly 22 is sleeved in the right end of the inner hole of the pipe string support ring 19 and fixed by the connecting part II 23. The pressure application seat assembly 22 is sealed with the pipe string support ring 19 using an O-ring. The central tube inner tube 14 is threadedly connected with the pipe string support ring 19. A support sand blocking ring I 3 and a filter screen I 5 are arranged in the annular space between the central tube inner tube 14 and the central tube casing 18. The support sand blocking ring I 3 and the filter screen I 5 can filter sand and impurities in the liquid. At the same time, the support sand blocking ring I also plays a supporting role for the central tube inner tube 14 and the central tube casing 18 to ensure their coaxiality. The track nail 9 is sleeved on the central tube casing 18. The track nail 9 can rotate and axially move along the central tube casing 18. The right side of the track nail 9 is limited by the step on the central tube casing 18. The adjustment component positioning ring (track nail limiting ring) 6 is sleeved on the central tube casing 18 and threadedly connected with the central tube casing 18. The adjustment component positioning ring 6 limits the left side of the track nail 9. The shear ring 2 is sleeved on the adjustment component positioning ring 6. The right end of the shear ring 2 abuts against the step of the adjustment component positioning ring 6. In the initial state, the shear ring 2 is fixedly connected with the lower sleeve 12 through the connecting part I 4.

[0113] Figure 3The figure is a schematic diagram of the free state structure of the downhole displacement switching device after the connectors I and II are cut off. During operation, under the action of high-pressure liquid, when the pressure reaches 3.5MPa, the connector I 4 is cut off, and the shear ring 2 falls due to its own gravity, and conflicts with the hydraulic jet radial drilling pipe column connected to the lower joint 1. Under the action of pressure, the reset spring 16 is compressed, and the central tube assembly moves downward under its own gravity and the thrust of the reset spring 16. At the same time, the anti-rotation nail 13 slides in the track groove of the central tube casing 18, and the track nail 9 contacts the second track ring 8, and the designed distance L1>L2. Continue to pressurize to 7MPa, the connector II 23 is cut off, and the pressing seat assembly 22 falls under the action of gravity, and its lower end is against the upper end of the central tube inner tube 14. The lower end of the pressing seat assembly 22 is axially opened with a liquid inlet groove, and the liquid can enter the central tube inner tube 14 through the liquid inlet groove. At this time, the connector I 4 and the connector II 23 are completely cut off, and the downhole displacement switching device is in a free state.

[0114] like Figure 4 As shown. When the window opening action is required, the high-pressure liquid enters the central tube inner tube 14 through the pressure seat assembly 22, and enters the annular space between the central tube inner tube 14 and the central tube sleeve 18 through the liquid outlet holes and liquid outlet seams at the bottom and side of the central tube inner tube 14, and is filtered by the supporting sand retaining ring I3 and the sand filter I5. The filtered liquid passes through the central tube sleeve 18 through the liquid hole and enters the closed space formed by the central tube sleeve 18, the upper sleeve 15 and the lower sleeve 12. As the pressure in the annular space continues to increase, the central tube assembly is pushed to compress the reset spring 16, the central tube assembly moves upward, and the track nail 9 enters the long track of the first track ring 11, thereby realizing the window opening operation. The design distance L4>L3, L5>L3.

[0115] like Figure 5 As shown, during the drilling operation, high-pressure liquid enters the central tube inner tube 14 through the punching seat assembly 22, and enters the annular space between the central tube inner tube 14 and the central tube casing 18 through the liquid outlet holes and liquid outlet seams at the bottom and sides of the central tube inner tube 14, and is filtered through the supporting sand retaining ring 13 and the sand filter net 15. The filtered liquid enters the closed space formed by the central tube casing 18, the upper sleeve 15 and the lower sleeve 12 through the liquid hole of the central tube casing 18. As the pressure in this annular space continues to increase, the central tube assembly is pushed to compress the reset spring 16, the central tube assembly moves upward, and the track nail 9 enters the short track of the first track ring 11, thereby realizing the perforating operation.

[0116] When the downhole displacement switching device provided by the above preferred embodiment is working, when it is lowered into the well, the downhole displacement switching device is in the initial state, and the pressure seat assembly 22 is in the sealed state. As the pipe string is lowered deeper, the pressure in the well rises, and the internal channel of the pressure seat assembly 22 is opened, connecting the displacement switching device with the upper pipeline of the device. This prevents the large pressure difference between the inside of the displacement switching device and the well from making it difficult to lower the device into the well. During operation, the high-pressure liquid enters the annular space between the upper joint 23 and the pipe string support ring 19, passes through the support sand control ring II 20 and the filter screen II 21 for filtration, and then enters the annular space between the central pipe assembly and the upper sleeve 15. The pressure acts on the step of the sleeve 15, generating an axial force between the central pipe assembly and the outer sleeve pipe assembly. This axial force acts on the connecting piece I 4. When the pressure reaches 3.5 MPa, the connecting piece I 4 is sheared off. The shear ring 2 falls due to its own gravity and abuts against the hydraulic jet radial drilling pipe string connected to the lower joint 1. After the connecting piece I 4 is sheared off, the central pipe assembly and the outer sleeve pipe assembly are not fixedly connected and can move axially. At this time, the return spring 16 is compressed, and the central pipe assembly moves downward under the action of gravity and the return spring 16. At the same time, the anti-rotation pin 13 slides in the track groove of the central pipe casing, and the track pin 9 contacts the second track ring 8. At this time, there is no relative movement between the central pipe assembly and the outer sleeve pipe assembly. Continue to apply pressure. At this time, because the track pin 9 contacts the first track ring 11, there is no relative displacement between the central pipe assembly and the outer sleeve pipe assembly. The pressure acts on the connecting piece II 23. When the pressure reaches 7 MPa, the connecting piece II 23 is sheared off. The pressure seat assembly 22 falls due to gravity, and its lower end abuts against the upper end of the inner pipe 14 of the central pipe. The lower end of the pressure seat assembly 22 is axially provided with a liquid inlet groove (i.e., the first liquid inlet channel), and the liquid can enter the inner pipe 14 of the central pipe through the liquid inlet groove. At this time, both the connecting piece I 4 and the connecting piece II 23 are sheared off, and the downhole displacement switching device is in a free state. When the window opening operation needs to be performed, the high-pressure liquid enters the inner pipe 14 of the central pipe through the pressure seat assembly 22, passes through the liquid outlet holes and liquid outlet slits at the bottom and side of the inner pipe 14 of the central pipe, enters the annular space between the inner pipe 14 of the central pipe and the central pipe casing 18 (i.e., the third fluid channel F), and is filtered by the support sand control ring I 3 and the filter screen I 5. The filtered liquid enters the closed space (i.e., the second accommodation cavity B) formed by the central pipe casing 18, the upper sleeve 15, and the lower sleeve 12 through the liquid passing hole 181 of the central pipe. As the pressure in the annular space continuously increases, it pushes the central pipe assembly to compress the return spring 16, and the central pipe assembly moves upward. The track pin 9 enters the long track (the second positioning groove 1103) of the upper first track ring 11, thus realizing the window opening operation. After the window opening operation is completed, the pressure is relieved, and the central pipe assembly moves downward under the action of its own gravity and the assistance of the return spring 16, returning to the free state. At this time, the track pin 9 is axially reset and rotates 45° in the circumferential direction.When drilling, high-pressure liquid enters the pressure test seat basket through the pressure application seat assembly 22, and enters the annular space between the inner pipe 14 of the central pipe and the central pipe casing 18 through the liquid outlet holes and liquid outlet slits at the bottom and side of the pressure test seat basket. It is filtered by the support sand retaining ring I 3 and the filter screen I 5, and the filtered liquid enters the closed space formed by the central pipe casing 18, the upper sleeve 15 and the lower sleeve 12 through the liquid passing hole 181 of the central pipe. As the pressure in the annular space continuously increases, the central pipe assembly is pushed to compress the return spring 16, and the central pipe assembly moves upward. The track pin 9 enters the short track (the first positioning groove 1102) of the first track ring 11, thereby realizing the drilling operation. When the drilling action is completed, the pressure is relieved, and the central pipe assembly moves downward due to its own gravity and the auxiliary action of the return spring 16 and returns to the free state. At this time, however, the track pin 9 is axially reset and rotates 45° in the circumferential direction. By repeatedly pressurizing, relieving pressure, and pressurizing in this way, the infinite switching between the window opening action and the drilling action can be realized. The fields where the problems described in the present invention occur include, but are not limited to, 5-inch or 5.5-inch oil wells.

[0117] For the downhole displacement switching device provided by the above-mentioned embodiment, only by changing the pressure inside the device can the switching of the track pin 9 between the second positioning groove 1103 and the first positioning groove 1102 in the first track ring 11 be realized, so as to perform displacement switching on the window opening and drilling positions. It has a sand prevention function and an auxiliary reset function of the return spring 16. The settings of the shear ring 2 and the adjustment assembly positioning ring 6 further improve the stability of the operation. During the process of the pipe string encountering resistance, the initial state of the position adjustment assembly can always remain unchanged before reaching the preset position, so that the two actions of window opening and drilling can be accurately predicted during use and no misoperation will occur; moreover, it will not affect the normal operation of the position adjustment assembly. The present invention is simple to operate, stable in performance, novel and ingenious in structural design, convenient and practical, and meets the on-site construction process.

[0118] The basic implementation of the present invention also provides a work string, which includes a tubing string, a drilling string and the above-mentioned downhole displacement switching device. The top of the downhole displacement switching device is connected to the bottom of the tubing string, and the bottom of the downhole displacement switching device is connected to the top of the drilling string. The drilling string is lowered into the predetermined drilling position in the well together with the tubing string and the downhole displacement switching device. This work string has all the advantages of the downhole displacement switching device and will not be elaborated here one by one.

[0119] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0120] It should be further noted that, for the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. In addition, any combination can be made among the various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A downhole displacement switching device is arranged at the bottom of the tubing and is lowered into a predetermined position in the well along with the tubing. It is characterized in that, The downhole displacement switching device includes a central pipe assembly and an outer sleeve pipe assembly. The outer sleeve pipe assembly is sleeved outside the central pipe assembly. A first accommodation cavity (A) and a second accommodation cavity (B) are formed between the inner wall of the outer sleeve pipe assembly and the outer wall of the central pipe assembly. A position adjustment assembly is arranged in the first accommodation cavity (A) and can adjust and position the position of the drilling pipe string when it is in the windowing state and the drilling state respectively; the central pipe assembly includes a position adjustment assembly positioning component connected to the outer sleeve pipe assembly, and the position adjustment assembly positioning component can slide off the outer sleeve pipe assembly under the action of the pressure P1 applied to the outer sleeve pipe assembly. When the position adjustment assembly positioning component is connected to the outer sleeve pipe assembly, the position adjustment assembly positioning component can prevent the position adjustment assembly from working. When the position adjustment assembly positioning component slides off the outer sleeve pipe assembly, the position adjustment assembly works normally; the second accommodation cavity (B) communicates with the inner cavity of the central pipe assembly, and fluid can enter the second accommodation cavity (B) through the inner cavity of the central pipe assembly, so as to form a pressure difference inside and outside the device through the entry of the fluid, and the central pipe assembly is lifted through this pressure difference. During the process of lifting the central pipe assembly, the lifting height of the central pipe assembly is positioned by the position adjustment assembly. The lifting height of the drilling pipe string when it is in the drilling state is less than the lifting height of the drilling pipe string when it is in the windowing state, so that the drilling pipe string can be aligned with the windowing position for drilling.

2. The downhole displacement switching device according to claim 1, characterized in that, It further includes a pressure application seat assembly (22). The pressure application seat assembly (22) is connected to the top end of the central pipe assembly, and the pressure application seat assembly (22) can slide off the top end of the central pipe assembly under the action of the pressure P2 applied to the pressure application seat assembly (22). The P2 is greater than the P1. When the pressure application seat assembly (22) does not slide off the top end of the central pipe assembly, the pressure application seat assembly (22) can prevent external fluid from entering the inner cavity of the central pipe assembly from the top end of the central pipe assembly, and can discharge the fluid in the inner cavity of the central pipe assembly from the top end of the central pipe assembly; when the pressure application seat assembly slides off the top end of the central pipe assembly, fluid can enter the inner cavity of the central pipe assembly from the pressure application seat assembly (22).

3. The downhole displacement switching device according to claim 2, wherein The pressure application seat assembly (22) includes a pressure application seat (221) and a one-way liquid inlet assembly. A first fluid channel (C) and a second fluid channel (D) are arranged on the pressure application seat (221). The one-way liquid inlet assembly is arranged in the second fluid channel (D). The fluid in the inner cavity of the central pipe assembly is suitable for being discharged from the second fluid channel (D), and the external fluid is suitable for entering the inner cavity of the central pipe assembly from the first fluid channel (C).

4. The downhole displacement switching device according to claim 3, characterized in that, The one-way liquid inlet assembly includes a first one-way damping seal (222), a second one-way damping seal (223), a one-way damping spring (224), and a one-way damping fixing member (226) arranged in sequence. One end of the one-way damping spring (224) abuts against the one-way damping fixing member (226), and the other end abuts against the second one-way damping seal (223). When the one-way liquid inlet assembly is not working, the second one-way damping seal (223) abuts against the first one-way damping seal (222). When the one-way liquid inlet assembly is working, the pressure difference before and after the one-way liquid inlet assembly compresses the one-way damping spring (224), and a gap for fluid to pass through is formed between the second one-way damping seal (223) and the first one-way damping seal (222).

5. The downhole displacement switching device according to claim 4, characterized in that, The one-way liquid inlet assembly further includes a one-way damping sleeve (225). One end of the first one-way damping seal (222) abuts against the pressure application seat (221), and the other end abuts against the one-way damping sleeve (225), and the one-way damping sleeve (225) is sleeved outside the one-way damping spring (224).

6. The downhole displacement switching device according to claim 5, characterized in that A connecting seal is arranged between the one-way damping seal (222) and the pressure application seat (221).

7. The downhole displacement switching device according to any one of claims 1 to 6, characterized in that, The central tube assembly includes a central tube inner tube (14) and a central tube outer sleeve (18) sleeved outside the central tube inner tube (14). The top end of the central tube inner tube (14) is hermetically connected to the central tube outer sleeve (18), and an opening is formed between the bottom end of the central tube inner tube (14) and the central tube outer sleeve (18). A third fluid passage (F) suitable for fluid to pass through is formed between the central tube outer sleeve (18) and the central tube inner tube (14), and a first sand blocking structure is further arranged between the central tube outer sleeve (18) and the central tube inner tube (14).

8. The downhole displacement switching device according to claim 7, characterized in that, The first sand blocking structure includes at least two support sand blocking rings I (3) and a sand filtering net I (5) arranged between adjacent support sand blocking rings I (3).

9. The downhole displacement switching device according to claim 7, characterized in that A filtering structure is arranged between the bottom end of the central tube inner tube (14) and the central tube outer sleeve (18).

10. The downhole displacement switching device according to claim 7, characterized in that, The central tube assembly further includes a pipe string support ring (19) connected to the top end of the central tube outer sleeve (18).

11. The downhole displacement switching device according to claim 10, wherein, A second sand blocking structure is arranged between the pipe string support ring (19) and the outer sleeve assembly.

12. The downhole displacement switching device according to claim 11, characterized in that, The second sand blocking structure includes at least two support sand blocking rings II (20) and a sand filtering net II (21) arranged between adjacent support sand blocking rings II (20).

13. The downhole displacement switching device according to claim 7, wherein, Central tube liquid passing holes (181) are arranged on the central tube outer sleeve (18), and the third fluid passage (F) is communicated with the second accommodation cavity (B) through the central tube liquid passing holes (181).

14. The downhole displacement switching device according to any one of claims 1 to 6, characterized in that, A third accommodation cavity (E) matching with the second accommodation cavity (B) is further formed between the inner wall of the outer sleeve assembly and the outer wall of the central tube assembly. When the volume of the second accommodation cavity (B) increases, the volume of the third accommodation cavity (E) decreases; when the volume of the second accommodation cavity (B) decreases, the volume of the third accommodation cavity (E) increases.

15. The downhole displacement switching device according to claim 14, characterized in that, A reset spring (16) is arranged in the third accommodating cavity (E). The reset spring (16) is arranged along the axial direction of the central pipe assembly. A protrusion of the central pipe assembly is arranged on the outer wall of the central pipe assembly, and a protrusion of the outer sleeve pipe assembly is arranged on the inner wall of the outer sleeve pipe assembly. One end of the reset spring (16) abuts against the protrusion of the central pipe assembly, and the other end abuts against the protrusion of the outer sleeve pipe assembly.

16. The downhole displacement switching device according to claim 15, characterized in that, A breathing hole (17) is arranged on the outer sleeve pipe assembly, and the breathing hole can communicate the third accommodating cavity (E) with the outside of the device.

17. The downhole displacement switching device according to claim 16, wherein, A breathing hole filter screen (172) is arranged in the breathing hole (17).

18. The downhole displacement switching device according to any one of claims 1 to 6, characterized in that, The adjusting component positioning component includes an adjusting component positioning ring (6) and a shear ring (2) sleeved on the central pipe assembly. One end of the adjusting component positioning ring (6) abuts against the position adjusting component, and the other end abuts against the shear ring (2). The shear ring (2) is detachably connected to the outer sleeve pipe assembly.

19. The downhole displacement switching device according to any one of claims 1 to 6, characterized in that, The position adjusting component includes a first track ring (11), a second track ring (8) and a track positioning ring (9). The first track ring (11) and the second track ring (8) are sequentially arranged in the first accommodating cavity from top to bottom. The first track ring (11) and the second track ring (8) are both sleeved on the outside of the central pipe assembly and can slide up and down. The outer walls of the first track ring (11) and the second track ring (8) are both connected to the inner wall of the outer sleeve pipe assembly. The track positioning ring (9) is sleeved on the outside of the central pipe assembly and can rotate circumferentially along the central pipe assembly. First positioning grooves (1102) and second positioning grooves (1103) are arranged at intervals along the circumferential direction of the bottom of the first track ring (11). The depth of the first positioning groove (1102) is greater than that of the second positioning groove (1103). Serrated first track protrusions (1101) are arranged between adjacent first positioning grooves (1102) and second positioning grooves (1103). Serrated second track protrusions (801) matching with the first track protrusions (1101) are arranged along the circumferential direction of the top of the second track ring (8). A spiral slideway is formed along the circumferential direction of the central pipe assembly between the top of the second track protrusion (801) and the bottom of the first track protrusion (1101). At least one track nail (901) is arranged on the outer wall of the track positioning ring (9), and the track nail (901) is arranged between the first track ring (11) and the second track ring. When the drilling string is in a free state, the bottom and the top of the track nail (901) respectively cooperate and abut against the top of the second track protrusion (801) and the bottom of the first track protrusion (1101). When the drilling string is in the window-opening state, the central pipe assembly is lifted to drive the trajectory positioning ring (9) to slide upward, and the trajectory pin (901) slides along the spiral slideway into the first positioning groove (1102), and the top of the trajectory pin (901) abuts against the top inner wall of the first positioning groove (1102). When the drilling string is in the drilling state, the central pipe assembly is lowered to enable the trajectory pin (901) to return to the spiral slideway. The central pipe assembly is lifted again to drive the trajectory positioning ring (9) to slide upward, and the trajectory pin (901) slides along the spiral slideway into the second positioning groove (1103) adjacent to the first positioning groove (1102), and the top of the trajectory pin (901) abuts against the top inner wall of the second positioning groove (1103).

20. The downhole displacement switching device according to claim 19, characterized in that, The cross-section of the trajectory pin (901) is triangular, the top inner walls of the first positioning groove (1102) and the second positioning groove (1103) are both inclined planes, and the top of the trajectory pin (901) can cooperate with and abut against the top inner walls of the first positioning groove (1102) and the second positioning groove (1103).

21. A work string, characterized in that, The working string includes a tubing string, a drilling string, and the downhole displacement switching device according to any one of claims 1 to 20, wherein: The top of the downhole displacement switching device is connected to the bottom of the tubing string, the bottom of the downhole displacement switching device is connected to the top of the drilling string, and the drilling string is lowered into a predetermined drilling position in the well together with the tubing string and the downhole displacement switching device.

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