Fishbone wellbore drilling device and power system thereof

Abstract

The present application relates to a kind of fishbone well drilling device and its power system, belong to the technical field of drilling completion.The power system of fishbone well drilling device of the present application adopts hydraulic cylinder, the piston rod of hydraulic cylinder is connected with hollow pipe joint, in turn drives hollow pipe to lift, and the liquid inlet interface on hollow pipe joint is used for ground injection system to inject liquid, hydraulic pump is used to inject oil to the rod cavity and rodless cavity of hydraulic cylinder, by limiting the movement of piston rod, it can be realized that fixed point is jetted, by speed control valve, the speed of the hydraulic oil entering the rodless cavity can be controlled, in turn, the extension speed of piston rod is controlled, in turn, the adjustment of the drilling speed of drilling device is realized, in the process of drilling, by alternating oil supply to rod and rodless cavity, the length of hollow pipe can be continuously increased to realize continuous drilling down, while after drilling is completed, hollow pipe can also be continuously removed to realize the removal of hollow pipe group.The pressure stability of hydraulic system is good, and the stability of the current fishbone well drilling device is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a fishbone well drilling device and its power system, belonging to the technical field of drilling and completion. BACKGROUND

[0002] The multi-branch fishbone well technology refers to a technology of realizing steering in a casing or open hole and drilling in a reservoir by a hydraulic rock breaking method through a small-diameter metal drill pipe. The technology is a new drilling and completion technology for liberating reservoirs under the premise of safe drilling and reservoir protection. The technology has good connectivity between the wellbore and the reservoir. Meanwhile, the technology changes the stimulation operation into a part of the drilling operation, forms multiple branches in the reservoir by the "parallel drilling" method to increase the exposed area of the reservoir, and does not need to perform the steps of casing, cementing, pipe scraping, perforating, and fracturing, etc. The technology is a drilling and completion technology between fracturing production and natural production.

[0003] In the application process of the technology, the rock breaking jetting fluid acts on the hydraulic rock breaking casing window drill bit to generate a pulling force on the drill pipe, thereby continuously pulling the hydraulic rock breaking casing window drill bit and the drill pipe into the formation. During the operation process, the fishbone well drilling device is usually required to realize the following processes:

[0004] (1) For a cased hole, the hydraulic rock breaking casing window drill bit is first required to perform point jetting on the casing to perform casing windowing operation, and then continuously break rocks for drilling;

[0005] (2) For an open hole, after the ground pump is pressed, a period of point jetting is still required to leave a migration time for the abrasive to reach the hydraulic rock breaking casing window drill bit from the ground;

[0006] (3) After the drilling is completed, the drill pipe is recovered and moved to the next layer for continuous operation.

[0007] The advance speed of the hydraulic rock breaking casing window drill bit and the drill pipe is different for different reservoir rock strengths, which requires the fishbone well drilling device to have the functions of point jetting, controllable and adjustable drilling speed, and drill pipe recovery, etc.

[0008] The invention patent application with the application publication number CN108952580A and the application publication date of December 7, 2018 discloses a drill pipe recoverable abrasive jet fishbone well drilling and completion device. The completion device can realize point jetting and continuous drilling jetting of the drill pipe, and can adjust the drilling speed of the drill pipe as required. The speed adjustment and point jetting of the above drilling device are both based on the downhole fluid as the medium, rely on the ground pump pressure to change the downhole fluid pressure, and then change the working mode. Since the downhole fluid pressure stability is poor, the drilling device has the problem of low working stability. SUMMARY

[0009] The fishbone well drilling device power system of the present application is used to solve the problem of low stability of the current fishbone well drilling device.

[0010] The fishbone well drilling device power system of the present application adopts the following technical scheme:

[0011] The fishbone well drilling device power system comprises:

[0012] The hydraulic cylinder comprises a cylinder body and a piston rod, and has a rod cavity and a rodless cavity inside, and the cylinder body is provided with a rod cavity oil port communicating with the rod cavity and a rodless cavity oil port communicating with the rodless cavity;

[0013] The hollow pipe joint is connected with the piston rod, and is used to detachably connect with the hollow pipe of the fishbone well drilling device, so that the piston rod can drive the hollow pipe to ascend and descend, and the hollow pipe joint is provided with a liquid inlet interface for the ground liquid injection system to inject liquid into the hollow pipe;

[0014] The hydraulic pump is used to alternately supply oil to the rodless cavity and the rod cavity;

[0015] The rodless cavity oil port is connected with a rodless cavity oil path for communicating with the oil tank, and the rod cavity oil port is connected with a rod cavity oil path for communicating with the oil tank, the rodless cavity oil path comprises a return oil branch and an oil inlet branch, the return oil branch is provided with a return control valve for unidirectional return of the hydraulic oil to the oil tank, and the oil inlet branch is provided with an oil inlet control valve for unidirectional inlet of the hydraulic oil into the rodless cavity and a speed regulating valve, the speed of the hydraulic oil into the rodless cavity is adjusted by adjusting the opening of the speed regulating valve, and then the extension speed of the piston rod is controlled; the return control valve can limit the hydraulic oil to enter the rodless cavity through the return oil branch, and the oil inlet control valve can limit the hydraulic oil to enter the oil tank through the oil inlet branch;

[0016] At least one of the rod cavity oil path and the rodless cavity oil path is provided with an oil path cutoff valve, the oil path cutoff valve is used to cut off the oil path where it is located to limit the movement of the piston rod, or the oil supply system cuts off the rodless cavity oil path through the return control valve and the oil inlet control valve to limit the movement of the piston rod to realize the fixed-point injection of the drilling device.

[0017] Beneficial effects: The power system of the fishbone well drilling device adopts a hydraulic cylinder, the piston rod of the hydraulic cylinder is connected with a hollow pipe joint, the hollow pipe joint is connected with a hollow pipe of the drilling device, and then drives the hollow pipe to ascend and descend, the liquid inlet interface on the hollow pipe joint is used for liquid injection of a ground liquid injection system, a hydraulic pump is used for injecting oil into the rod cavity and the rodless cavity of the hydraulic cylinder, the movement of the piston rod can be limited to realize fixed-point injection, the speed of the hydraulic oil entering the rodless cavity can be controlled through a speed regulating valve, and then the extension speed of the piston rod is controlled, and then the drilling speed of the drilling device is adjusted, in the drilling process, the length of the hollow pipe can be continuously increased to realize continuous downward drilling by alternately supplying oil to the rod cavity and the rodless cavity, and after drilling is completed, the hollow pipe can also be continuously removed to realize dismounting of the hollow pipe group. The pressure stability of the hydraulic system is good, the influence of the external environment is small, and the stability of the current fishbone well drilling device is improved.

[0018] Further, the oil supply system comprises an oil supply reversing valve, the oil supply reversing valve has a rodless cavity oil supply port and a rod cavity oil supply port, and the oil supply reversing valve is used for switching the on-off of the oil path between the hydraulic pump and the rodless cavity, and is also used for switching the on-off of the oil path between the hydraulic pump and the rod cavity. The rod cavity and the rodless cavity can share one hydraulic pump through the oil supply reversing valve, and the structure of the system is simplified.

[0019] Further, the oil supply reversing valve is a three-position four-way reversing valve, the spool of the oil supply reversing valve has a rod cavity oil supply position for connecting the hydraulic pump and the rod cavity, a rodless cavity oil supply position for connecting the hydraulic pump and the rodless cavity, and a cut-off position for disconnecting the hydraulic pump, the rod cavity and the rodless cavity.

[0020] Further, a rod cavity cutoff valve is arranged between the oil supply reversing valve and the rod cavity. The cutoff valve is used for cutting off the path between the rod cavity and the hydraulic pump, and protecting the hydraulic pump from impact.

[0021] Further, the oil inlet control valve is a spring-loaded hydraulic control check valve, and the oil inlet control valve is arranged downstream of the speed regulating valve. The spring-loaded hydraulic control check valve can set the opening pressure as required, so that the extension speed of the piston rod meets the expected requirement.

[0022] Further, the oil return control valve is a spring-loaded hydraulic control check valve. The spring-loaded hydraulic control check valve can set the opening pressure as required, so that the piston rod is quickly retracted.

[0023] Further, the hydraulic cylinder is a double-acting multi-stage hydraulic cylinder.

[0024] The technical scheme of the fishbone well drilling device of the present application is as follows:

[0025] The fishbone well drilling device comprises a hollow pipe, a drill pipe and a power system, and the power system comprises:

[0026] The hydraulic cylinder comprises a cylinder body and a piston rod, and has a rod cavity and a rodless cavity in the hydraulic cylinder.

[0027] The hollow pipe joint is connected with the piston rod, and is used for detachable connection with the hollow pipe of the fishbone well drilling device, so that the piston rod can drive the hollow pipe to ascend and descend.

[0028] The hydraulic pump is used for alternately supplying oil to the rod cavity and the rodless cavity.

[0029] The rodless cavity oil port is connected with a rodless cavity oil path for communication with the oil tank, and the rod cavity oil port is connected with a rod cavity oil path for communication with the oil tank.

[0030] At least one of the rod cavity oil path and the rodless cavity oil path is provided with an oil path cutoff valve for cutting off the oil path to limit the movement of the piston rod, or the oil supply system cuts off the rodless cavity oil path through the return control valve and the oil inlet control valve to limit the movement of the piston rod and realize the fixed-point injection of the drilling device.

[0031] The fishbone well drilling device power system adopts the hydraulic cylinder, the piston rod of the hydraulic cylinder is connected with the hollow pipe joint, the hollow pipe joint is connected with the hollow pipe of the drilling device, and then the hollow pipe is driven to ascend and descend.

[0032] Further, the oil supply system comprises an oil supply reversing valve having a rodless cavity oil supply port and a rod cavity oil supply port, and the oil supply reversing valve is used to switch the on-off of the oil path between the hydraulic pump and the rodless cavity, and is used to switch the on-off of the oil path between the hydraulic pump and the rod cavity. The rod cavity and the rodless cavity can share one hydraulic pump through the oil supply reversing valve, and the structure of the system is simplified.

[0033] Further, the oil supply reversing valve is a three-position four-way reversing valve, and a valve core of the oil supply reversing valve has a rod cavity oil supply position for connecting the hydraulic pump and the rod cavity, a rodless cavity oil supply position for connecting the hydraulic pump and the rodless cavity, and a cut-off position for disconnecting the hydraulic pump, the rod cavity and the rodless cavity.

[0034] Further, the oil supply reversing valve is provided with a rod cavity cut-off valve between the oil supply reversing valve and the rod cavity. The rod cavity cut-off valve is used to cut off the path between the rod cavity and the hydraulic pump, and the hydraulic pump is protected from impact.

[0035] Further, the oil inlet control valve is a spring-loaded hydraulic control check valve, and the oil inlet control valve is arranged downstream of the speed regulating valve. The spring-loaded hydraulic control check valve can set the opening pressure according to the requirement, so that the piston rod extension speed meets the expected requirement.

[0036] Further, the oil return control valve is a spring-loaded hydraulic control check valve. The spring-loaded hydraulic control check valve can set the opening pressure according to the requirement, so that the piston rod is quickly retracted.

[0037] Further, the hydraulic cylinder is a double-acting multi-stage hydraulic cylinder.

[0038] Further, the fishbone well drilling device comprises a drill pipe recovery device, and the drill pipe recovery device comprises:

[0039] a housing for being lowered into a well, having a hollow cavity;

[0040] a center pipe having a hollow pipe connecting end for being connected with a hollow pipe and a drill pipe connecting end for being connected with a drill pipe, and being slidably arranged in the housing, the center pipe being provided with a piston segment in sealing sliding cooperation with an inner wall surface of the cavity, the piston segment dividing the cavity into a first sealing cavity and a second sealing cavity, the first sealing cavity being located on a side of the second sealing cavity close to the hollow pipe connecting end, and an end surface area of the piston segment facing the first sealing cavity being smaller than an end surface area of the piston segment facing the second sealing cavity;

[0041] a first liquid inlet hole provided on a cavity wall of the first sealing cavity and used for connecting an annulus outside the housing with the first sealing cavity;

[0042] a second liquid inlet hole provided on a cavity wall of the second sealing cavity and used for connecting the annulus outside the housing with the second sealing cavity.

[0043] When the drill pipe needs to be recovered, the liquid is pressed into the first sealing cavity and the second sealing cavity from the first liquid inlet hole and the second liquid inlet hole respectively, so that the pressure of the first sealing cavity and the second sealing cavity is equal, the end face area of the piston section facing the first sealing cavity is smaller than the end face area of the piston section facing the second sealing cavity, so the liquid in the second sealing cavity has a greater thrust on the piston section than the liquid in the first sealing cavity, and the center pipe section moves towards the first sealing cavity, so as to realize the recovery of the drill pipe. The whole drill pipe recovery process is simple to operate, and the center pipe does not need to be blocked, so the structure of the fishbone well drilling pipe recovery device can be simplified.

[0044] Further, the first sealing cavity is provided with an annular sealing cavity on the side close to the hollow pipe connecting end, the annular sealing cavity is arranged along the sliding direction of the center pipe, both ends of the annular sealing cavity along the sliding direction of the center pipe are in sealing cooperation with the center pipe, and the annular sealing cavity is surrounded by the shell and the center pipe. The arrangement of the annular sealing cavity can prolong the guiding cooperation stroke of the shell and the center pipe in the sliding direction of the center pipe, and can effectively avoid the jamming of the center pipe relative to the shell during movement. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a structural schematic view of the fishbone well drilling device in embodiment 1 of the present application;

[0046] Figure 2 is a structural schematic view of the drill pipe recovery device in embodiment 1 of the fishbone well drilling device of the present application;

[0047] In the figure: 1, shell; 2, center pipe; 3, centralizer; 4, drill pipe; 5, casing window drill bit; 6, piston section; 7, first sealing cavity; 8, second sealing cavity; 9, first center pipe section; 10, second center pipe section; 11, annular sealing cavity; 12, first liquid inlet hole; 13, second liquid inlet hole; 14, filter screen; 15, spring; 16, annular sealing cavity; 17, shell; 18, first liquid inlet hole; 19, second liquid inlet hole; 20, upper shell; 21, lower shell; 22, hydraulic cylinder; 23, cylinder body; 24, piston rod; 241, primary movable rod; 242, secondary movable rod; 25, rod cavity; 26, rodless cavity; 27, rod cavity oil port; 28, rodless cavity oil port; 29, hollow pipe joint; 30, liquid inlet hose; 31, hydraulic pump; 32, oil supply reversing valve; 33, rod cavity shut-off valve; 34, oil tank; 35, oil return branch; 36, oil inlet branch; 37, oil return control valve; 38, oil inlet control valve; 39, speed regulating valve; 40, oil path shut-off valve; 41, hollow pipe. DETAILED DESCRIPTION

[0048] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application, i.e., the described examples are only a part of the examples of the present application, but not all the examples. The components of the embodiments of the present application generally described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0049] Therefore, the detailed description of the embodiments of the present application provided in the accompanying drawings below is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0050] It should be noted that the relationship terms such as "first" and "second" and the like that can appear are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0051] The features and performances of the present application will be further described in detail in combination with the examples.

[0052] Specific embodiment 1 of the fishbone well drilling device of the present application:

[0053] As shown in Figure 1 , the fishbone well drilling device includes hollow pipes 41, drill pipes 4, casing window drill bits 5 fixed at the end of the drill pipes 4, a power system for driving the movement of the hollow pipes 41, and a drill pipe recovery device for recovering the drill pipes 4. The hollow pipes 41 are provided in multiple numbers, and adjacent hollow pipes are threadedly connected. The number of hollow pipes can be increased or decreased according to the drilling depth.

[0054] The power system comprises a hydraulic cylinder 22, which is a double-acting multi-stage hydraulic cylinder in this embodiment. The use of a multi-stage hydraulic cylinder can achieve a large stroke through a relatively short hydraulic cylinder. The hydraulic cylinder 22 comprises a cylinder body 23 and a piston rod 24, and the piston rod 24 is a combined two-stage telescopic rod, which comprises a first movable rod 241 and a second movable rod 242. The hydraulic cylinder 22 has a rod cavity 25 and a rodless cavity 26, and the cylinder body 23 is provided with a rod cavity oil port 27 communicating with the rod cavity 25 and a rodless cavity oil port 28 communicating with the rodless cavity 26.

[0055] The piston rod 24 is connected with a hollow pipe joint 29, which is threadedly connected with a hollow pipe 41, so that the piston rod 24 can drive the hollow pipe 41 to ascend and descend, and the hollow pipe joint and the hollow pipe can be detached. A plurality of hollow pipes 41 are provided, and the specific number thereof is determined according to the drilling depth. The threadedly connected hollow pipe joint 29 and hollow pipe 41 are convenient to disassemble, which facilitates the addition of new hollow pipes below the hollow pipe joint 29 and the removal of the hollow pipes connected with the hollow pipe joint. The hollow pipe joint 29 is provided with a liquid inlet port for a ground liquid injection system to inject liquid into the hollow pipe 41, and the liquid inlet port is connected with a liquid inlet hose 30 connected with a ground pump of the ground liquid injection system.

[0056] The power system further comprises a hydraulic pump 31 for supplying oil to the rodless cavity 26 and the rod cavity 25, and the hydraulic pump 31 is connected with an oil supply reversing valve 32, which is a three-position four-way reversing valve. The oil supply reversing valve 32 has a rodless cavity oil supply port and a rod cavity oil supply port, and is used to switch the oil path between the hydraulic pump 31 and the rodless cavity 26, and simultaneously used to switch the oil path between the hydraulic pump 31 and the rod cavity 25. The spool of the oil supply reversing valve 32 has a rod cavity oil supply position for connecting the hydraulic pump 31 and the rod cavity 25, a rodless cavity oil supply position for connecting the hydraulic pump 31 and the rodless cavity 26, and a cut-off position for disconnecting the hydraulic pump 31, the rod cavity 25 and the rodless cavity 26. A rod cavity cutoff valve 33 is arranged between the oil supply reversing valve 32 and the rod cavity 25 for protecting the hydraulic pump 31.

[0057] The rodless cavity oil port 28 is connected with a rodless cavity oil path in communication with the oil tank 34, and the rod cavity oil port 27 is connected with a rod cavity oil path for communication with the oil tank 34, the rodless cavity oil path includes an oil return branch 35 and an oil inlet branch 36, the oil return branch 35 is provided with an oil return control valve 37 for unidirectional return of hydraulic oil to the oil tank 34, and the oil inlet branch 36 is provided with an oil inlet control valve 38 and a speed regulating valve 39 for unidirectional inlet of hydraulic oil into the rodless cavity 26; the oil return control valve 37 can limit the hydraulic oil to enter the rodless cavity 26 through the oil return branch 35, and the oil inlet control valve 38 can limit the hydraulic oil to enter the oil tank 34 through the oil inlet branch 36; the oil inlet control valve 38 and the oil return control valve 37 are both spring-loaded hydraulic control one-way valves, and the oil inlet control valve 38 is arranged downstream of the speed regulating valve 39. The spring-loaded hydraulic control one-way valve includes a valve body, a valve core and a spring exerting force on the valve core, the valve body is provided with a valve port, and the spring exerts force on the valve core to block the valve port.

[0058] The oil path cutoff valve 40 is arranged on the rod cavity oil path, and is used to cut off the rod cavity oil path to limit the movement of the piston rod 24, so that the oil in the rod cavity 25 cannot be discharged, and the fixed-point injection of the casing windowing drill bit 5 is realized.

[0059] The power system of the fishbone stinger drilling device realizes fixed-point injection of the drilling device and adjusts the operating speed of the casing windowing drill bit 5, and when the oil pipe is taken out, the hollow pipe 41 can be taken out section by section through the power system.

[0060] When the drilling device needs fixed-point injection, the high-pressure abrasive slurry passes through the liquid inlet hose 30 and the hollow pipe 41 in the machine, enters the drill pipe 4 from the hollow pipe 41 and generates a pulling force on the casing windowing drill bit 5, drives the first movable rod 241 and the second movable rod 242 to generate a downward movement trend, and the rod cavity cutoff valve 33 and the oil path cutoff valve 40 are both in the closed state, so that the hydraulic oil cannot be discharged from the rod cavity 25 of the hydraulic cylinder 22, and therefore the casing windowing drill bit 5 does not move, so that the fixed-point injection operation, i.e. casing windowing, is performed.

[0061] When the drilling speed needs to be adjusted, the valve core of the oil supply reversing valve 32 is in the closed position, the oil path cut-off valve 40 is opened, and the rod cavity cut-off valve 33 is in the closed state. At this time, the pressure drop P1 generated by the high-pressure abrasive slurry on the casing window drill bit 5 is a set rock breaking pressure drop, which is much greater than the rock breaking threshold pressure to ensure the rock breaking efficiency. The resulting tension is F1. Since the oil path cut-off valve 40 has been opened, hydraulic oil can be discharged from the rod cavity 25 of the hydraulic cylinder 22 to the oil tank 34, and hydraulic oil can also be sucked into the rodless cavity 26 of the hydraulic cylinder 22 from the oil tank 34 through the oil inlet control valve 38 and the speed regulating valve. Therefore, the casing window drill bit 5 can continue to move downward. Adjusting the opening pressure of the oil inlet control valve 38 to be equal to the suction pressure generated by the tension F1 in the rodless cavity 26 of the hydraulic cylinder 22, and adjusting the opening degree of the speed regulating valve, the running speed of the casing window drill bit 5 can be consistent with the desired speed.

[0062] As shown in Figure 2 The drill pipe recovery device includes a housing 1 and a central pipe 2. The housing 1 is provided with a centralizer 3 outside for being lowered into the well. The housing 1 has a hollow cylindrical cavity. The central pipe 2 has a hollow pipe connecting end at one end for connecting with a hollow pipe 41, through which abrasive jet can be introduced into the central pipe 2. The other end of the central pipe 2 is connected with a drill pipe 4. The drill pipe 4 has a suspended end, and a casing window drill bit 5 is welded on the suspended end. The casing window drill bit 5 is used to spray abrasive jet to drill the rock formation.

[0063] The central pipe 2 is coaxially arranged with the cylindrical housing 1 and penetrates the housing 1, so that the central pipe 2 is slidably arranged on the housing 1. The central pipe 2 is sealingly fitted with both ends of the housing 1 in the sliding direction. Specifically, a sealing groove is arranged on the housing 1 at the position in contact with the central pipe 2, and a sealing ring is arranged in the sealing groove to achieve the sealing fit between the housing 1 and the central pipe 2.

[0064] A piston segment 6 is arranged on the central pipe 2 to sealingly slide with the inner wall of the cavity of the housing 1. A sealing groove is arranged on the outer circumferential surface of the piston segment 6, and a sealing ring is arranged in the sealing groove to achieve the sealing fit between the piston segment 6 and the inner wall of the cavity. The piston segment 6 divides the cavity into a first sealing cavity 7 and a second sealing cavity 8. Both the first sealing cavity 7 and the second sealing cavity 8 are annular cavities formed by the central pipe 2 and the housing 1. In the sliding direction of the central pipe 2, the first sealing cavity 7 is located on the side of the second sealing cavity 8 close to the hollow pipe connecting end.

[0065] In this embodiment, as shown in Figure 2As shown, the arrangement of the piston section 6 divides the central pipe 2 into a first central pipe section 9 and a second central pipe section 10 in the sliding direction of the central pipe 2, the first central pipe section 9 is located on the side of the second central pipe section 10 close to the hollow pipe connecting end, and the outer diameter size of the first central pipe section 9 is greater than that of the second central pipe section 10, so that the end face area of the piston section 6 towards the first sealing cavity 7 is smaller than that towards the second sealing cavity 8.

[0066] The central pipe 2 reciprocally slides on the housing 1 along the axis direction of the central pipe 2 to realize the extension and retraction of the central pipe end drilling pipe 4 relative to the housing 1. In this embodiment, an annular sealing cavity 11 is arranged on the side of the first sealing cavity 7 close to the hollow pipe connecting end, the annular sealing cavity 11 is one, and the annular sealing cavity 11 is surrounded by the central pipe 2 and the housing 1, and the annular sealing cavity 11 is arranged along the axis of the central pipe 2 to improve the guiding property of the central pipe 2 during reciprocating sliding relative to the housing 1, which can effectively avoid the jamming of the central pipe 2 during sliding relative to the housing 1.

[0067] In this embodiment, as shown in the figure, Figure 2 A first liquid inlet hole 12 is arranged on the cavity wall of the first sealing cavity 7, and a second liquid inlet hole 13 is arranged on the cavity wall of the second sealing cavity 8, the first liquid inlet hole 12 is used to communicate the first sealing cavity 7 and the annulus outside the housing between the housing 1 and the well wall, and the second liquid inlet hole 13 is used to communicate the second sealing cavity 8 and the annulus outside the housing between the housing 1 and the well wall.

[0068] In this embodiment, as shown in the figure, Figure 2 The first liquid inlet hole 12 is arranged on the circumferential side wall of the first sealing cavity 7, the first liquid inlet hole 12 is a circular hole, and the axis of the first liquid inlet hole 12 extends radially along the housing 1, the first liquid inlet hole 12 is close to the hollow pipe connecting end and away from the drilling pipe connecting end, so as to avoid the piston section 6 blocking the first liquid inlet hole 12 during the retraction of the central pipe 2 relative to the housing 1, and to make the central pipe 2 have a larger retraction stroke relative to the housing 1. The second liquid inlet hole 13 is arranged at the drilling pipe connecting end, the second liquid inlet hole 13 is a circular hole, and the axis of the second liquid inlet hole 13 extends radially along the housing 1, and the position of the second liquid inlet hole 13 is arranged to avoid the piston section 6 blocking the second liquid inlet hole 13 during the extension of the central pipe 2 relative to the housing 1, and to make the central pipe 2 have a larger extension stroke relative to the housing 1.

[0069] In this embodiment, a filter screen 14 is arranged in each of the first liquid inlet hole 12 and the second liquid inlet hole 13, so as to avoid impurities in the annulus outside the housing from entering the first sealing cavity 7 and the second sealing cavity 8, thereby affecting the sliding of the central pipe 2 relative to the housing 1.

[0070] In the embodiment, the second sealing cavity 8 is provided with a reset spring 15, the reset spring 15 is sleeved on the second center pipe section 10, one end of the reset spring 15 is pressed on the piston section 6, and the other end is pressed on the cavity wall of the second sealing cavity 8, so as to limit the length of the center pipe 2 extending out of the housing 1, and avoid the second liquid inlet hole 13 being blocked during the extension of the center pipe 2.

[0071] In the embodiment, the housing 1 of the drilling device is provided in a split type, so as to realize the sliding assembly of the center pipe 2 and the housing 1. Specifically, the housing 1 comprises an upper housing 20 and a lower housing 21, the upper housing 20 and the lower housing 21 are sealingly inserted and assembled, and the upper housing 20 and the lower housing 21 are connected through threads, the lower end of the upper housing 20 is provided with an external thread section, an upper sealing insertion section is arranged above the external thread section, a sealing groove is arranged on the sealing insertion section, a sealing ring is arranged in the sealing groove, the lower housing 21 is provided with an internal thread section matched with the external thread section of the upper housing 20, and a sealing insertion matching section matched with the sealing insertion section is arranged above the internal thread section, the inner diameter size of the sealing insertion matching section is larger than that of the internal thread section. During the assembly of the center pipe 2 and the housing 1, the center pipe 2 is sealingly inserted and assembled in the upper housing 20, then the lower housing 21 is sealingly sleeved on the center pipe 2, and the lower housing 21 is sealingly inserted and assembled with the upper housing 20 and connected through threads, so as to realize the sealing sliding assembly of the center pipe 2 and the housing 1.

[0072] During the working of the drilling device, the drilling device is lowered to the reservoir position in the main borehole, the abrasive jet is input into the center pipe 2, the abrasive jet generates a pulling force on the drill pipe 4, and then drives the drill pipe 4 and the center pipe 2 to extend out of the housing 1 and into the reservoir, so as to perform jet drilling on the branch well. In the embodiment, the drill pipe 4 is made of titanium alloy material, and can be repeatedly bent, so as to improve the strength of the drill pipe 4.

[0073] When the branch well drilling is completed, the input of the abrasive jet into the center pipe 2 is stopped, at this time, under the action of the reset spring 15, the center pipe 2 is retracted to the housing 1 by a certain distance, then liquid is input into the annular space outside the housing, the liquid enters into the first sealing cavity 7 and the second sealing cavity 8 through the first liquid inlet hole 12 and the second liquid inlet hole 13 respectively, so as to equalize the pressure in the first sealing cavity 7 and the second sealing cavity 8, the force of the liquid in the second sealing cavity 8 on the piston section 6 is F1, the force of the liquid in the first sealing cavity 7 on the piston section 6 is F2, F1>F2, so the center pipe 2 moves towards the wellhead direction relative to the housing 1, and the drill pipe 4 is retracted towards the main borehole direction under the driving of the center pipe 2, the first liquid inlet hole 12 is close to the hollow pipe connecting end and far away from the drill pipe connecting end, so that the center pipe 2 has a longer retraction stroke.

[0074] The first sealing cavity 7 and the second sealing cavity 8 are not communicated with the internal space of the central pipe 2, and during the recovery of the drill pipe 4, a valve core structure for plugging the central pipe 2 is not needed, the structure of the drilling device can be simplified, and the recovery of the drill pipe 4 in the drilling device is facilitated.

[0075] The working process of the drilling device is as follows:

[0076] The first movable rod 241 and the second movable rod 242 are completely retracted into the hydraulic cylinder 22, and then the rod cavity cutoff valve 33 and the oil way cutoff valve 40 are closed; the high-pressure abrasive slurry pumped by the ground is sequentially passed through the liquid inlet hose 30, the hollow pipe joint 29 and the hollow pipe 41 into the central pipe 2, and is delivered to the drill pipe 4 and the casing window drill bit 5 by the central pipe 2; the high-pressure abrasive slurry generates a pulling force on the casing window drill bit 5, and then drives the central pipe 2, the hollow pipe assembly, the first movable rod 241 and the second movable rod 242 to generate a downward movement trend; since the rod cavity cutoff valve 33 and the oil way cutoff valve 40 are both in the closed state, the hydraulic oil cannot be discharged from the rod cavity 25 of the hydraulic cylinder 22, and therefore the casing window drill bit 5 does not move, so that the "fixed-point jetting" operation, i.e. the casing windowing, is performed.

[0077] After a certain time, the casing window operation is completed, the valve core of the oil supply reversing valve 32 is in the closed position, the oil passage cut-off valve 40 is opened, but the rod cavity cut-off valve 33 is still in the closed state, at this time the pressure drop of the high-pressure abrasive slurry on the casing window drill bit 5 is P1, the oil passage cut-off valve 40 is opened, the hydraulic oil can be discharged from the rod cavity 25 of the hydraulic cylinder 22 to the oil tank 34, and the hydraulic oil can also be sucked into the rodless cavity 26 of the hydraulic cylinder 22 through the oil inlet control valve 38 and the speed regulating valve 39, therefore, the center pipe 2, the hollow pipe assembly, the first movable rod 241 and the second movable rod 242 can continue to move downward. The opening pressure of the oil inlet control valve 38 is adjusted to be equal to the suction pressure generated by the pulling force F1 in the rodless cavity 26 of the hydraulic cylinder 22; at the same time, the opening degree of the speed regulating valve 39 is adjusted to make the running speed of the casing window drill bit 5 consistent with the expected speed; if the ground pump, the liquid inlet hose 30, the hollow pipe joint 29 and the like leak, the pressure drop of the high-pressure abrasive slurry on the casing window drill bit 5 is P2 (P2 < P1), then the oil inlet control valve 38 will automatically close, the casing window drill bit 5 stops running and switches to the fixed-point jetting state, after the fault is eliminated and the pressure drop is restored to P1 (or greater than P1), the oil inlet control valve 38 is automatically opened again, the casing window drill bit 5 continues to carry out the rock breaking drilling operation, and after the current drilling distance is equivalent to the length of the hollow pipe 41, the ground pump is stopped, the hollow pipe 41 is separated from the hollow pipe joint 29, then the oil passage cut-off valve 40 is closed and the rod cavity cut-off valve 33 is opened, and the hydraulic pump 31 is started, the hydraulic oil is injected into the rod cavity 25 of the hydraulic cylinder 22, and at the same time the hydraulic oil is pressed out from the rodless cavity 26 of the hydraulic cylinder 22 and enters the oil tank 34 through the oil return control valve 37, because the opening pressure of the oil return control valve 37 is low and the diameter is large, therefore, the first movable rod 241 and the second movable rod 242 can be quickly retracted; after the first movable rod 241 and the second movable rod 242 are completely retracted, another hollow pipe 41 is connected in series on the basis of the existing hollow pipe 41, then the hollow pipe joint 29 is connected, and the drilling operation is continued; the above process is repeatedly performed until the drill pipe completely enters the reservoir.

[0078] After the drill pipe 4 completely enters the reservoir, the rock breaking drilling operation is completed, and the drill pipe 4 is recovered by annular pressure, the specific operation method is that the annulus between the downhole drill pipe 4 recovery module 3 and the casing is pressurized, the liquid passes through the first downhole annulus fluid inlet hole 12 and the second downhole annulus fluid inlet hole 13 and enters the first sealing cavity 7 and the second sealing cavity 8 after being filtered, and acts on the upper and lower ends of the piston section 6, because the force receiving area of the lower end of the piston section 6 is greater than that of the upper end, therefore, under the push of the annulus liquid pressure, the center pipe 2 rises, when the first movable rod 241 and the second movable rod 242 are completely retracted, a hollow pipe 41 is removed, then the valve core of the oil supply reversing valve 32 is switched to the position of the rodless cavity liquid inlet and the rod cavity liquid outlet of the hydraulic cylinder 22, the hydraulic pump 31 is started, the first movable rod 241 and the second movable rod 242 are quickly extended, then the hollow pipe 41 to be removed is connected, and the above process is repeated until the drill pipe 4 is completely recovered.

[0079] Specific embodiment 2 of the fishbone wellbore drilling device of the present application:

[0080] The difference from the above-mentioned embodiments is that two hydraulic pumps are arranged in the present embodiment, and the two hydraulic pumps work alternately and supply oil to the rod cavity and the rodless cavity respectively.

[0081] Specific embodiment 3 of the fishbone wellbore drilling device of the present application:

[0082] The difference from the above-mentioned embodiments is that the oil supply system cuts off the oil path of the rodless cavity through the return control valve and the inlet control valve to limit the movement of the piston rod in the present embodiment. The return control valve and the inlet control valve are both solenoid valves, and are controlled to be opened and closed by the controller.

[0083] Specific embodiment 4 of the fishbone wellbore drilling device of the present application:

[0084] The difference from the above-mentioned embodiments is that the piston rod of the hydraulic cylinder is of an integrated structure, and the hydraulic cylinder is a double-acting single-stage hydraulic cylinder. In other embodiments, the piston rod can also be a three-stage movable rod structure, and the hydraulic cylinder is a double-acting three-stage hydraulic cylinder.

[0085] Specific embodiment 5 of the fishbone wellbore drilling device of the present application:

[0086] The difference from the above-mentioned embodiments is that:

[0087] The annular sealed cavities formed by the shell and the center pipe are provided with two, and are arranged along the axial direction of the center pipe to further improve the guiding property of the relative sliding of the center pipe relative to the shell.

[0088] Specific embodiment 6 of the fishbone wellbore drilling device of the present application:

[0089] The difference from the above-mentioned embodiments is that the first inlet hole and the second inlet hole are respectively provided with two, and are arranged along the circumferential direction of the shell at uniform intervals, and a filter screen is arranged in each inlet hole to improve the stability during the sliding process of the center pipe relative to the shell.

[0090] Specific embodiment 7 of the fishbone wellbore drilling device of the present application:

[0091] The difference from the above-mentioned embodiment is that no spring is arranged in the second sealing cavity, so as to simplify the structure of the whole drilling device and shorten the assembly time of the drilling device.

[0092] The specific embodiment 8 of the fishbone well drilling device of the present application is as follows:

[0093] The difference from the above-mentioned embodiment is that the first liquid inlet hole is arranged at the middle position of the first sealing cavity along the extension direction of the central pipe, and the corresponding second liquid inlet hole is arranged on the circumferential side wall of the second sealing cavity and located at the middle position of the second sealing cavity along the extension direction of the central pipe, and the spring is arranged to make the piston segment located at the second liquid inlet hole close to the wellhead side when the central pipe is extended to the limit position relative to the shell, so as to make the central pipe extend and retract in a small range relative to the shell, and ensure the structural stability of the whole drilling device in the working process.

[0094] The specific embodiment 9 of the fishbone well drilling device of the present application is as follows:

[0095] The difference from the above-mentioned embodiment is that no filter screen is arranged in the first liquid inlet hole and the second liquid inlet hole.

[0096] The specific embodiment 10 of the fishbone well drilling device of the present application is as follows:

[0097] The difference from the above-mentioned embodiment is that only the first sealing cavity and the second sealing cavity are arranged between the central pipe and the shell, and no annular sealing cavity is arranged, so as to realize the guided movement of the central pipe relative to the shell, and at the same time, the structure of the shell can be simplified, and the processing of the shell is facilitated.

[0098] The specific embodiment 11 of the fishbone well drilling device of the present application is as follows:

[0099] The difference from the above-mentioned embodiment is that an external thread is arranged on the drill pipe, and an internal thread is arranged at the corresponding position of the central pipe connected with the drill pipe, and the internal and external threads are matched to realize the threaded connection of the drill pipe and the central pipe.

[0100] The specific embodiment 12 of the fishbone well drilling device of the present application is as follows:

[0101] The difference from the above-mentioned embodiments is only that the shell comprises a shell body and a lower cover body, the lower cover body is an annular cover body as a whole, the second liquid inlet hole is arranged on the lower cover body, an outer threaded segment is arranged on the outer circumferential surface of the annular cover body, a sealing plug-in segment is arranged below the outer threaded segment, a sealing groove is arranged on the outer circumferential surface of the sealing plug-in segment, a sealing ring is arranged in the sealing groove, an inner threaded segment is arranged at the lower end of the shell body, a sealing plug-in cooperation segment that is in sealing cooperation with the sealing plug-in segment is arranged below the inner threaded segment, and in the process of assembling the shell and the central pipe, the central pipe is first sealingly plugged into the shell body, then the lower cover body is sealingly sleeved on the central pipe, and the lower cover body is sealingly plug-in cooperated with the shell body and connected through threads, so as to realize the sealing sliding assembly of the central pipe and the shell.

[0102] The specific embodiment of the power system of the fishbone well drilling device of the present application is as follows:

[0103] The structure of the power system of the fishbone well drilling device of the present application is the same as that of the power system in any of the specific embodiments of the fishbone well drilling device described above, and will not be repeated here.

[0104] The above is only a preferred embodiment of the present application, and is not used to limit the present application, the patent protection scope of the present application is subject to the claims, any equivalent structural changes made by using the content of the specification and drawings of the present application should be included in the protection scope of the present application.

Claims

1. A power system for a fishbone-bone well drilling device, characterized in that, include: The hydraulic cylinder (22) includes a cylinder body (23) and a piston rod (24); the hydraulic cylinder (22) has a rod chamber (25) and a rodless chamber (26) inside, and the cylinder body (23) is provided with a rod chamber port (27) communicating with the rod chamber (25) and a rodless chamber port (28) communicating with the rodless chamber (26); Hollow tube connector (29) is connected to piston rod (24). Hollow tube connector (29) is used to detachably connect to hollow tube (41) of fishbone well drilling device so that piston rod (24) can drive hollow tube (41) to rise and fall. Hollow tube connector (29) is provided with a liquid inlet for the surface liquid injection system to inject liquid into hollow tube (41). Hydraulic pump (31) is used to alternately supply oil to the rodless chamber (26) and the rod chamber (25); The rodless chamber port (28) is connected to a rodless chamber oil passage for communication with the oil tank (34), and the rod chamber port (27) is connected to a rod chamber oil passage for communication with the oil tank (34). The rodless chamber oil passage includes a return branch (35) and an inlet branch (36). The return branch (35) is equipped with a return control valve (37) for one-way return of hydraulic oil to the oil tank (34). The inlet branch (36) is equipped with an inlet control valve (38) and a speed control valve (39) for one-way entry of hydraulic oil into the rodless chamber (26). The speed of hydraulic oil entering the rodless chamber (26) is adjusted by adjusting the opening of the speed control valve (39), thereby controlling the extension speed of the piston rod. The return control valve (37) can restrict the hydraulic oil from entering the rodless chamber (26) through the return branch (35), and the inlet control valve (38) can restrict the hydraulic oil from entering the oil tank (34) through the inlet branch (36). At least one of the rod chamber oil circuit and the rodless chamber oil circuit is provided with an oil circuit shut-off valve (40). The oil circuit shut-off valve (40) is used to shut off the oil circuit to limit the movement of the piston rod (24). Alternatively, the oil supply system can shut off the rodless chamber oil circuit through the return oil control valve (37) and the inlet oil control valve (38) to limit the movement of the piston rod (24) and achieve point injection of the drilling device.

2. The power system of the fishbone well drilling device according to claim 1, characterized in that, The oil supply system includes an oil supply directional valve (32), which has a rodless chamber oil supply port and a rod chamber oil supply port. The oil supply directional valve (32) is used to switch the oil circuit between the hydraulic pump (31) and the rodless chamber (26), and at the same time, it is used to switch the oil circuit between the hydraulic pump (31) and the rod chamber (25).

3. The power system of the fishbone well drilling device according to claim 2, characterized in that, The oil supply directional valve (32) is a three-position four-way directional valve. The valve core of the oil supply directional valve (32) has a rod chamber oil supply position that connects the hydraulic pump (31) and the rod chamber (25), a rodless chamber liquid supply position that connects the hydraulic pump (31) and the rodless chamber (26), and a cut-off position that disconnects the hydraulic pump (31), the rod chamber (25), and the rodless chamber (26).

4. The power system of the fishbone well drilling device according to claim 3, characterized in that, A rod chamber shut-off valve (33) is provided between the oil supply reversing valve (32) and the rod chamber (25).

5. The power system for the fishbone well drilling device according to any one of claims 1-4, characterized in that, The oil inlet control valve (38) is a spring-loaded hydraulic check valve, and the oil inlet control valve (38) is located downstream of the speed control valve (39).

6. The power system for the fishbone well drilling device according to any one of claims 1-4, characterized in that, The return oil control valve (37) is a spring-loaded hydraulic check valve.

7. The power system for the fishbone well drilling device according to any one of claims 1-4, characterized in that, The hydraulic cylinder (22) is a double-acting multi-stage hydraulic cylinder (22).

8. A fishbone-shaped well drilling device, comprising a hollow tube (41), a drill pipe (4), and a power system, characterized in that, The power system is the power system of the fishbone well drilling device as described in any one of claims 1-7.

9. The fishbone-shaped well drilling device according to claim 8, characterized in that, Fishbone well drilling rigs include a drill pipe recovery device, which includes: The shell (17), used for being lowered into the well, has a hollow cavity; The central tube (2) has a hollow tube connection end for connecting with the hollow tube (41) at one end and a drill pipe connection end for connecting with the drill pipe (4) at the other end. It is slidably mounted on the housing (17). The central tube (2) is provided with a piston section (6) that is in sealing and sliding fit with the inner wall surface of the cavity. The piston section (6) divides the cavity into a first sealing cavity (7) and a second sealing cavity (8). The first sealing cavity (7) is located on the side of the second sealing cavity (8) close to the hollow tube connection end. The end face area of ​​the piston section (6) facing the first sealing cavity (7) is smaller than the end face area facing the second sealing cavity (8). The first liquid inlet hole (18) is provided on the cavity wall of the first sealed cavity (7) for connecting the outer annulus of the shell with the first sealed cavity (7); The second liquid inlet (13) is provided on the cavity wall of the second sealing cavity (8) and is used to connect the outer annulus of the housing with the second sealing cavity (8).

10. The fishbone-shaped well drilling device according to claim 9, characterized in that, The first sealing cavity (7) is provided with an annular sealing cavity (11) on one side near the hollow tube connection end. The annular sealing cavity (11) extends along the sliding direction of the central tube (2). Both ends of the annular sealing cavity (11) along the sliding direction of the central tube (2) are sealed and fitted with the central tube (2). The annular sealing cavity (11) is formed by the shell (17) and the central tube (2).

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