A dual tubing release for lateral drilling

Abstract

The utility model belongs to the drilling and lining integrated well completion technical field, concretely relates to a double -tube release device of easy side tracking. Double -tube release device of easy side tracking includes: the outer tube is provided with the clamping groove at the inner wall of outer tube, and the lower extreme of outer tube is connected easy drill pipe, the inner tube is coaxially arranged in the outer tube, and the radial movement is provided with the stop piece along the lateral wall of inner tube, is provided with the stop groove in the inner wall of inner tube, and the lower extreme of inner tube is connected first oil pipe, and the outer diameter of first oil pipe is less than the inner diameter of easy drill pipe, the piston assembly is coaxially arranged in the inner tube through the shearing pin, is provided with the recess in the outer wall of piston assembly, and is provided with the stop ring for with the stop groove adaptation in the outer wall of piston assembly, in the first state, piston assembly radial abuts the inboard of stop piece, so that the outboard of stop piece is connected with clamping groove, in the second state, piston assembly moves to the position of recess reaching stop piece relative to inner tube, so that stop piece can move to the disengagement clamping groove radially inwards.

Description

Technical Field

[0001] This utility model belongs to the field of drilling-lining integrated well completion technology, specifically, it relates to a double-tube release device that facilitates side-drilling. Background Technology

[0002] In the drill-liner integrated drilling and completion process, to meet the requirements of later open-hole sidetracking, a liner is usually first run to support the open-hole section. There is an axial gap between the upper end of the liner and the upper end of the open-hole section. Then, the lower end of the upper tubing string (small-diameter tubing) is inserted back into the liner to form a continuous tubing working channel. When sidetracking is required in the open-hole section, the upper tubing string is separated from the liner, pulled out of the well, and the open-hole section is exposed. Then, sidetracking tools are run to perform sidetracking in the open-hole section.

[0003] In actual operation, the above process has many technical problems: the use of small-sized tubing for reinsertion makes it impossible to determine whether the reinsertion is in place and the circulation channel is not sealed, which affects the normal construction of coiled tubing; if the well wall of the open hole section becomes unstable and collapses, it may even bury the connection between the upper tubing string and the liner, making it impossible to pull the upper tubing string out of the well, which increases the difficulty of handling.

[0004] The aforementioned technical problems urgently need to be solved. Utility Model Content

[0005] In view of the technical problems mentioned above, the present invention aims to provide a double-tube release device that facilitates side drilling.

[0006] According to this utility model, a double-tube release device for easy side drilling is provided, comprising: The outer cylinder has a groove on its inner wall, and the lower end of the outer cylinder is connected to an easy-drill tube. An inner cylinder is coaxially arranged inside the outer cylinder. A stop is provided on the side wall of the inner cylinder in a radially movable manner. An anti-reverse groove is provided on the inner wall of the inner cylinder. The lower end of the inner cylinder is connected to a first oil pipe. The outer diameter of the first oil pipe is smaller than the inner diameter of the easy-drill pipe. A piston assembly is coaxially mounted in the inner cylinder via a shear pin. A groove is provided on the outer wall of the piston assembly, and a retaining ring is provided on the outer wall of the piston assembly to fit the retaining groove. In the first state, the piston assembly radially abuts against the inner side of the stop member, such that the outer side of the stop member is connected to the slot; In the second state, the piston assembly moves relative to the inner cylinder until the groove reaches the stop, allowing the stop to move radially inward to disengage from the slot.

[0007] In one specific embodiment, a lower connector for connecting a first oil pipe is provided at the lower end of the inner cylinder. The inner diameter of the upper end of the lower connector is smaller than the inner diameter of the inner cylinder. The outer wall of the upper end of the piston assembly is sealed with the inner wall of the inner cylinder, and the outer wall of the lower end of the piston assembly is sealed with the inner wall of the lower connector, thereby forming a pressure differential surface at both axial ends of the piston assembly.

[0008] In one specific embodiment, the piston assembly includes an upper piston and a lower piston arranged coaxially from top to bottom. The upper end of the upper piston is sealed to the inner cylinder. The outer wall of the lower end of the upper piston is sealed to the inner wall of the upper end of the lower piston by a threaded connection. The outer wall of the upper end of the lower piston is sealed to the inner cylinder. The outer wall of the lower end of the lower piston is sealed to the lower connector.

[0009] In one specific embodiment, the upper piston and the lower piston are coaxially connected by a threaded connection, and threadlocker is applied to the connection between the upper piston and the lower piston.

[0010] In one specific embodiment, the stop is located above the lower piston, and the groove is provided on the inner wall of the upper piston.

[0011] In one specific embodiment, the stop member includes a support ring and a key block. The support ring is coaxially disposed on the outer side of the upper piston, and the key block is radially movable on the side wall of the outer cylinder. In the first state, the inner side of the key block abuts radially against the support ring; In the second state, the key block moves upward relative to the support ring and disengages from the support ring.

[0012] In one specific embodiment, high-temperature grease is provided in the first cavity formed between the upper piston, the inner cylinder and the lower piston and the second cavity formed between the lower piston, the inner cylinder and the lower connector.

[0013] In one specific embodiment, the outer cylinder and the inner cylinder are provided with connection holes on their side walls, which connect the first cavity and the second cavity to the outside world respectively.

[0014] In one specific embodiment, the outer cylinder includes a first outer shell and a second outer shell coaxially arranged from top to bottom, the slot is disposed on the inner wall of the first outer shell, and the lower end of the second outer shell is used to connect an easy-drill pipe.

[0015] In one specific embodiment, a fastening pin is provided between the first housing and the second housing.

[0016] Compared with the prior art, this application has at least the following advantages.

[0017] This utility model's dual-tube release device includes an outer cylinder, an inner cylinder housed within the outer cylinder via a stop, and a piston assembly housed within the inner cylinder. A drillable tube is coaxially positioned at the lower end of the outer cylinder, and a first tubing is coaxially positioned at the lower end of the inner cylinder. During well completion, the upper end of the inner cylinder of the dual-tube release device is connected to a second tubing. After entering the well, the first tubing at the lower end of the dual-tube release device connects to the liner to form a circulation channel for oil and gas extraction. The drillable tube at the lower end of the dual-tube release device is fixedly connected to the liner in the well, protecting the first tubing. When sidetracking is required, because the drillable tube is installed outside the first tubing, even if the open-hole section experiences wellbore instability and collapse, only the drillable tube will be buried, not the first tubing. Therefore, the piston assembly can be moved relative to the inner cylinder by pressurization, releasing the connection between the stop and the outer cylinder. The inner cylinder, piston assembly, and first tubing can then be smoothly pulled out, leaving the outer cylinder and drillable tube in the well. Later, the outer cylinder and drillable tube are drilled out before sidetracking.

[0018] The easy-drill pipe has poor corrosion resistance. In this invention, the first oil pipe is connected to the liner to form a circulation channel, so that the produced fluid will not or only comes into contact with the easy-drill pipe, thereby improving the service life of the easy-drill pipe and increasing the success rate of subsequently pulling the first oil pipe out of the reconnection plug body. Attached Figure Description

[0019] The present invention will now be described with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of an embodiment of the dual-tube dropper provided by the present invention in its first state; Figure 2 This is a schematic diagram of an embodiment of the dual-tube dropper provided by the present invention in a second state; Figure 3 for Figure 2 An enlarged schematic diagram of part A in the middle; Figure 4 for Figure 2 Enlarged schematic diagram of part B; Figure 5 A schematic diagram of one embodiment of a drill-liner integrated drilling process where the liner remains inside the well. Figure 6 This is a schematic diagram of one embodiment of the completion string provided by this utility model; Figure 7 This is a schematic diagram of one embodiment of the well completion string provided by this utility model when side-drilling is required.

[0021] Figure label: 1. Liner; 2. Connector; 3. Reconnector plug; 4. First tubing; 5. Dual-tube release device; 6. Packer; 7. Second tubing; 8. Easy-drill tubing; 50. Connecting hole; 51. Outer cylinder; 511. Slot; 513. First outer shell; 514. Second outer shell; 52. Inner cylinder; 521. Anti-reverse groove; 53. Shear pin; 54. Piston assembly; 540. Groove; 541. Upper piston; 542. Lower piston; 543. Anti-reverse ring; 55. Stop; 551. Support ring; 552. Key block; 56. Lower connector; 57. Upper connector; 58. First cavity; 59. Second cavity; 91. O-ring seal; 92. O-ring back seal; 93. Fastening pin; 100. Completion string; 101. Open hole section; 102. Casing section.

[0022] In this application, all the accompanying drawings are schematic drawings, used only to illustrate the principle of the present invention, and are not drawn to scale. Detailed Implementation

[0023] The present invention will now be described with reference to the accompanying drawings.

[0024] It should be noted that in this application, the direction of the completion string near the wellhead after being inserted into the well according to this utility model is described as "up," "forward," or similar terms, while the direction of the well string away from the wellhead after being inserted into the well is described as "down," "back," or similar terms. In this application, "axial" refers to the direction pointed to by the central axis of the dual-tube release device 5, that is... Figure 1 The vertical direction; "radial" refers to the direction perpendicular to the central axis of the double-tube dropper 5; "inner side" refers to the direction close to the central axis of the double-tube dropper 5; "outer side" refers to the direction away from the central axis of the double-tube dropper 5.

[0025] Figure 1 The structure of the double-tube dropper 5 according to this utility model is shown. Figure 1 As shown, the double-tube release device 5 includes an outer cylinder 51, an inner cylinder 52, a stop 55, and a piston assembly 54.

[0026] In this embodiment, the outer cylinder 51, inner cylinder 52, and piston assembly 54 are all constructed in a generally cylindrical shape. A groove 511 is provided on the inner wall of the outer cylinder 51, and the lower end of the outer cylinder 51 is used for coaxially fixing the easy-drilling pipe 8. The inner cylinder 52 is coaxially disposed inside the outer cylinder 51, and the lower end of the inner cylinder 52 is used for coaxially fixing the first oil pipe 4. The outer diameter of the first oil pipe 4 is smaller than the inner diameter of the easy-drilling pipe 8. The upper end of the inner cylinder 52 is used for coaxially fixing the second oil pipe 7. The radial dimension of the second oil pipe 7 is not limited, but it is preferably set to be larger than the radial dimension of the first oil pipe 4 to provide a larger diameter for oil and gas extraction. The piston assembly 54 is coaxially disposed inside the inner cylinder 52, and a groove 540 is provided on the outer wall of the piston assembly 54. The stop member 55 is radially movable on the side wall of the inner cylinder 52, and the stop member 55 penetrates the side wall of the inner cylinder 52. That is, the radially inner side of the stop member 55 can move to the inner side of the inner wall of the inner cylinder 52, and the radially outer side of the stop member 55 can move to the outer side of the outer wall of the inner cylinder 52.

[0027] In the first state, the piston assembly 54 is coaxially disposed inside the inner cylinder 52, and the shear pin 53 radially penetrates the inner cylinder 52 and the piston assembly 54, preventing the piston assembly 54 from moving axially relative to the inner cylinder 52. At this time, the groove 540 of the piston assembly 54 is located above the stop member 55, the inner side of the stop member 55 radially abuts against the outer wall of the piston assembly 54, and the outer side of the stop member 55 radially inserts into the slot 511 of the outer cylinder 51, so that the stop member 55 radially penetrates the side walls of the inner cylinder 52 and the outer cylinder 51, thereby preventing the inner cylinder 52 from moving axially relative to the outer cylinder 51.

[0028] In this embodiment, in the first state, the lower end face of the first oil pipe 4 is lower than the lower end face of the easy-drilling pipe 8. For example... Figure 6 As shown, the double-tube release device 5 is used to connect with the liner 1 in the well to form a completion string 100. There is an axial gap between the upper end face of the liner 1 and the upper end face of the open hole section 101. When using the double-tube release device 5 to assemble the completion string 100, the lower end of the inner cylinder 52 of the double-tube release device 5 is inserted into the liner 1 through the first tubing 4, and communicates with the liner 1 to form a circulation channel. At this time, the outer cylinder 51 of the double-tube release device 5 is fixedly connected to the liner 1 through the easy-drill pipe 8. The easy-drill pipe 8 is coaxially located outside the first tubing 4 and does not participate in the construction of the circulation channel. During the oil and gas extraction process, the oil and gas in the formation pass from bottom to top through the liner 1, the first tubing 4, the inner cylinder 52, and the second tubing 7 to reach the wellhead. The easy-drill pipe 8 is located outside the first tubing 4 and is fixedly connected to the upper end of the liner 1. After the well wall of the open hole section 101 collapses, the rock cuttings and other debris generated can only fall onto the outer wall of the easy-drill pipe 8, and will not fall into the insertion position between the first tubing 4 and the liner 1. This avoids the rock cuttings and other debris from getting stuck between the first tubing 4 and the liner 1, so that the first tubing 4 can be successfully separated from the liner 1 in subsequent processes, thereby improving the success rate of subsequent process implementation.

[0029] According to this utility model, the outer diameter of the first oil pipe 4 is matched with the inner diameter of the liner 1, so that the first oil pipe 4 can be inserted into the liner 1. The outer wall of the first oil pipe 4 and the inner wall of the liner 1 can be set to an unsealed connection or to be sealed to each other, as long as it does not affect the extraction of oil and gas.

[0030] Although the first oil pipe 4 in this embodiment is set to be inserted into the liner 1, this is not intended to limit the scope of protection of this utility model, as long as the inner cavities of the first oil pipe 4 and the liner 1 can be interconnected to form a circulation channel.

[0031] In one specific embodiment, when the double-tube release device 5 is connected to the liner 1 in the well to form a completion string 100, the upper end face of the outer cylinder 51 is not lower than the upper end face of the open hole section 101, thereby preventing rock cuttings and other debris generated after the well wall of the open hole section 101 collapses from falling between the outer cylinder 51 and the inner cylinder 52 and burying the outer cylinder 51 and the inner cylinder 52.

[0032] In a specific embodiment, such as Figure 6 As shown, a connector 2 is located at the upper end of the liner 1, and a reconnection plug 3 for fixed connection with the connector 2 is provided at the lower end of the easy-drill pipe 8 at the lower end of the dual-tube release device 5. The lower end of the first tubing 4 passes through the inner cavity of the reconnection plug 3. During the assembly of the completion string 100 using the dual-tube release device 5, the reconnection plug 3 below the dual-tube release device 5 can dock with the connector 2 to form an axially fixed connection. When assembling the completion string 100 using the dual-tube release device 5, the length of the first tubing 4 can be set to only insert into the connector 2 without inserting into the liner 1, or it can be set to pass through the connector 2 and be inserted into the liner 1.

[0033] Easy-drill tubing 8 is an oil pipe made of a material that is easy to drill out. Easy-drill tubing is well known to those skilled in the art and will not be described in detail here.

[0034] In the second state, by increasing the internal pressure of the inner cylinder 52 through pressure buildup, the piston assembly 54 can respond to the internal pressure of the inner cylinder 52 by shearing the shear pin 53 and moving downward relative to the inner cylinder 52. This causes the groove 540 on the outer wall of the piston assembly 54 to move to the position of the stop member 55, that is, the groove 540 and the stop member 55 are in the same radial plane. Figure 2 As shown. At this time, the stop 55 can move radially inward relative to the inner cylinder 52, thereby disengaging from the slot 511 of the outer cylinder 51, allowing the inner cylinder 52 to move relative to the outer cylinder 51. When side-drilling is required, the second tubing 7 is pulled up to remove the inner cylinder 52 and the first tubing 4 from the well, while the outer cylinder 51 and the easy-drill pipe 8 remain in the well. After drilling out the outer cylinder 51 and the easy-drill pipe 8 to expose the open hole section 101, side-drilling can then be performed on the open hole section 101.

[0035] It is easy to understand that the internal pressure of the inner cylinder 52 can be increased by dropping a pressure-pressurizing ball into the well and then pressurizing it. The ball seat that is compatible with the pressure-pressurizing ball can be set at the lower end of the inner cylinder 52 (below the piston assembly 54), or inside the first oil pipe 4, or between the inner cylinder 52 and the first oil pipe 4.

[0036] According to this utility model, such as Figure 1 As shown, a lower connector 56 is coaxially fixed at the lower end of the inner cylinder 52 via a threaded connection, and the lower end of the lower connector 56 is used to connect to the first oil pipe 4. An upper connector 57 is coaxially fixed at the upper end of the inner cylinder 52 via a threaded connection, and the upper end of the upper connector 57 is used to connect to the second oil pipe 7.

[0037] In this embodiment, an external thread is provided on the outer wall of the lower end of the upper connector 57, and an internal thread is provided on the inner wall of the upper end of the inner cylinder 52. The lower end of the upper connector 57 extends into the upper end of the inner cylinder 52 and is fixedly connected to each other by the threads. A fastening pin is also radially provided between the upper connector 57 and the inner cylinder 52. A sealing assembly is provided between the outer wall of the upper connector 57 and the inner wall of the inner cylinder 52.

[0038] In a preferred embodiment, the sealing assembly includes an O-ring 91 and O-ring back rings 92 disposed on both axial sides of the O-ring 91.

[0039] The lower connector 56 has an external thread on its upper outer wall and an internal thread on its lower inner wall. The lower end of the lower connector 56 extends into the lower end of the inner cylinder 52 and is fixedly connected to it by the threads. A fastening pin is also radially provided between the lower connector 56 and the inner cylinder 52.

[0040] The upper cross-sectional area of ​​the piston assembly 54 is larger than that of the lower cross-sectional area, thus forming a pressure differential surface between the upper and lower ends of the piston assembly 54. In this embodiment, the outer diameter of the upper end of the piston assembly 54 is larger than that of the lower end. The upper end of the piston assembly 54 is located within the axial range of the inner cylinder 52, and a sealing assembly is provided between the outer wall of the upper end of the piston assembly 54 and the inner wall of the inner cylinder 52. The upper end of the inner diameter of the lower connector 56 is smaller than the inner diameter of the inner cylinder 52, and the lower end of the piston assembly 54 is located within the axial range of the lower connector 56. A sealing assembly is provided between the outer wall of the lower end of the piston assembly 54 and the inner wall of the lower connector 56. When the internal pressure of the inner cylinder 52 increases, the forces on the two axial end faces of the piston assembly 54 are different, thus causing it to move downward relative to the inner cylinder 52 under the action of the pressure differential force.

[0041] In one specific embodiment, the piston assembly 54 includes an upper piston 541 and a lower piston 542 coaxially connected from top to bottom. The upper piston 541 has external threads on its lower outer wall, and the lower piston 542 has internal threads on its upper inner wall. The upper piston 541 and lower piston 542 are coaxially fixedly connected by these threads. Furthermore, threadlocker is applied to the connecting threads of the upper piston 541 and lower piston 542 to enhance the seal. A sealing assembly is also provided at the connection point of the upper piston 541 and lower piston 542.

[0042] The outer diameter of the upper end of the upper piston 541 is larger than the outer diameter of the lower end of the lower piston 542. The upper piston 541 is located within the axial range of the inner cylinder 52, and a sealing assembly is provided between the outer wall of the upper end of the upper piston 541 and the inner wall of the inner cylinder 52. The lower end of the lower piston 542 is located within the axial range of the lower connector 56, and a sealing assembly is provided between the inner wall of the lower piston 542 and the outer wall of the lower connector 56. In the first state, there is an axial gap between the upper end face of the lower piston 542 and the lower connector 56, providing space for the downward movement of the piston assembly 54.

[0043] In this embodiment, the stop 55 is located within the axial range of the upper piston 541 and above the lower piston 542, and the groove 540 is located on the inner wall of the upper piston 541.

[0044] In one specific embodiment, the stop member 55 includes a support ring 551 and a key block 552. The support ring 551 is coaxially disposed on the outside of the upper piston 541, and the key block 552 is radially movable within the side wall of the outer cylinder 51. Figure 1 As shown, in the first state, the inner side of the key block 552 radially abuts against the outer side of the support ring 551. At this time, the key block 552 cannot move radially inward relative to the outer cylinder 51, and therefore cannot disengage from the slot 511 of the outer cylinder 51. Figure 2 and Figure 3 As shown, in the second state, the piston assembly 54 moves downward relative to the inner cylinder 52, and the support ring 551 moves downward relative to the key block 552 along with the inner cylinder 52. Finally, the outer side of the support ring 551 no longer abuts against the key block 552, and the key block 552 corresponds to the position of the groove 540, so that the key block 552 can move radially into the groove 540 and disengage from the slot 511 of the outer cylinder 51.

[0045] In this embodiment, a retaining ring 543 is provided on the outer wall of the piston assembly 54, and a retaining groove 521 for fitting the retaining ring 543 is provided on the inner wall of the inner cylinder 52. In the first state, as... Figure 1 As shown, the anti-reverse ring 543 is located above the anti-reverse groove 521, and the anti-reverse ring 543 is in a contracted state under the compression of the inner wall of the inner cylinder 52. In the second state, as... Figure 2 and Figure 4As shown, the anti-reverse ring 543 moves downward relative to the inner cylinder 52 under the drive of the piston assembly 54. When the anti-reverse ring 543 moves to the position of the anti-reverse groove 521, the anti-reverse ring 543 is no longer squeezed by the inner wall of the inner cylinder 52, and thus expands radially under its own elastic force, and is stuck into the anti-reverse groove 521 to prevent the piston assembly 54 from resetting upward relative to the inner cylinder 52.

[0046] In one specific embodiment, the anti-reverse ring 543 is disposed on the outer wall of the lower piston 542.

[0047] In this embodiment, a first cavity 58 is formed between the upper piston 541, the inner cylinder 52 and the lower piston 542, and a second cavity 59 is formed between the lower piston 542, the inner cylinder 52 and the lower connector 56. High-temperature grease is provided in the first cavity 58 and the second cavity 59.

[0048] In this embodiment, connection holes 50 are provided on the side walls of the outer cylinder 51 and the inner cylinder 52 to connect the first cavity 58 and the second cavity 59 to the outside world, respectively, for balancing the pressure of the first cavity 58 and the second cavity 59 with the outside world.

[0049] In this embodiment, the outer cylinder 51 includes a first outer shell 513 and a second outer shell 514 arranged coaxially from top to bottom. The first outer shell 513 and the second outer shell 514 are coaxially fixedly connected by a threaded connection, and a fastening pin 93 is radially inserted between the first outer shell 513 and the second outer shell 514.

[0050] A connection hole 50 for connecting to the first cavity 58 is provided on the side wall of the first housing 513, and a connection hole 50 for connecting to the second cavity 59 is provided on the side wall of the second housing 514. A slot 511 is provided on the inner wall of the first housing 513, and the lower end of the second housing 514 is used to connect the easy-drill tube 8.

[0051] Figure 6 The structure of the well completion string 100 according to this utility model is shown. For example... Figure 6 As shown, the completion string 100 includes a liner 1, a connector 2, a reconnection plug 3, a first tubing 4, a double tubing release device 5, a second tubing 7, and an easy-drill tubing 8.

[0052] The liner 1 is installed inside the open hole section 101, and there is an axial gap between the upper end face of the liner 1 and the upper end face of the open hole section 101 to leave space for subsequent side-drilling. The reconnector 3 is coaxially connected to the connector 2 at the upper end of the liner 1 via the connector 2. It should be noted that, in this embodiment, the connector 2 at the upper end of the liner 1 is a part of the release assembly left after the drilling string above the liner 1 is released after drilling is completed in the drill-liner integrated drilling process. The drill-liner integrated drilling process is well known to those skilled in the art and will not be described in detail here. The easy-drill pipe 8 is coaxially fixedly installed at the upper end of the reconnector 3. The lower end of the outer cylinder 51 of the double-tube release device 5 is coaxially fixedly connected to the upper end of the easy-drill pipe 8. The first tubing 4 is coaxially installed at the lower end of the inner cylinder 52 of the double-tube release device 5 and forms a circulation channel with the liner 1. The lower end of the second tubing 7 is coaxially fixedly connected to the upper end of the inner cylinder 52 of the double-tube release device 5.

[0053] Furthermore, the upper end face of the outer cylinder 51 of the double-tube release device 5 is not lower than the upper end face of the open hole section 101, thereby preventing rock cuttings generated after the well wall of the open hole section 101 collapses from falling between the outer cylinder 51 and the inner cylinder 52.

[0054] The completion process for a 100mm completion string is as follows.

[0055] like Figure 5 As shown, first, the liner 1 is lowered into the well, with its upper end face positioned below the upper end face of the open hole section 101, leaving space for subsequent sidetracking. Then, at the wellhead, the first tubing 4 is coaxially connected to the lower end of the inner cylinder 52 of the double-tubing release device 5, the easy-drill pipe 8 is coaxially connected to the lower end of the outer cylinder 51 of the double-tubing release device 5, the reconnector 3 is coaxially connected to the lower end of the easy-drill pipe 8, and the second tubing 7 is coaxially connected to the upper end of the inner cylinder 52 of the double-tubing release device 5. The packer 6 is then installed on the outer wall of the second tubing 7. It is then lowered into the well until the reconnector 3 is axially fixedly connected to the connector 2 at the upper end of the liner 1. Afterwards, the wellhead string position is adjusted, and the packer 6 is set, as shown... Figure 6 As shown.

[0056] The structure of packer 6 is well known to those skilled in the art and will not be described in detail here.

[0057] According to this utility model, a method for constructing a well completion string is also provided, including the following steps.

[0058] First, the liner 1 is lowered into the well, with its upper end face positioned below the upper end face of the open hole section 101, leaving space for subsequent side-drilling. Figure 5As shown. It should be noted that in this embodiment, a connector 2 is provided at the upper end of the liner 1. The connector 2 is a part of the release component left after the drilling string above the liner 1 is released after drilling is completed in the drill-liner integrated drilling process. The drill-liner integrated drilling process is well known to those skilled in the art and will not be described in detail here.

[0059] Then, at the wellhead, the first tubing 4 is coaxially connected to the lower end of the inner cylinder 52 of the double-tube release device 5, the easy-drill pipe 8 is coaxially connected to the lower end of the outer cylinder 51 of the double-tube release device 5, the reconnection plug 3 is coaxially connected to the lower end of the easy-drill pipe 8, the second tubing 7 is coaxially connected to the upper end of the inner cylinder 52 of the double-tube release device 5, and the packer 6 is installed on the outer wall of the second tubing 7, forming a tubing string. It is easy to understand that a ball seat for subsequent ball-dropping and pressure buildup is provided at the lower end of the inner cylinder 52 (below the piston assembly 54), or between the inner cylinder 52 and the first tubing 4, or inside the first tubing 4.

[0060] Then, the above-mentioned pipe string is lowered into the well until the reconnector 3 is axially fixedly connected to the connector 2.

[0061] Then, a pressure ball is placed into the ball seat and pressed down, increasing the internal pressure of the inner cylinder 52, thereby pushing the piston assembly 54 downward relative to the inner cylinder 52, so that the stop 55 is no longer connected to the slot 511 of the outer cylinder 51. Figure 7 As shown, the inner cylinder 52 can move axially relative to the outer cylinder 51, allowing the first tubing 4, inner cylinder 52, and second tubing 7 to move upwards or downwards, adjusting the position of the wellhead string and facilitating the installation of the wellhead equipment. The process of adjusting the wellhead string position is as follows: The second tubing 7 is composed of multiple short tubings connected in series. When the reconnector 3 is fixedly connected to the connector 2, if the upper end of the second tubing 7 exceeds the specified height of the wellhead, the second tubing 7 is lifted, and the uppermost short tubing of the second tubing 7 is replaced with a shorter tubing, so that when the first tubing 4 is subsequently re-inserted into the liner 1, the uppermost end of the second tubing 7 can be located at the specified height of the wellhead. The process of replacing the uppermost short tubing of the second tubing 7 when adjusting the wellhead string position is well known to those skilled in the art and will not be described in detail here.

[0062] Then, the first tubing 4, inner cylinder 52, and second tubing 7 are lowered, so that the first tubing 4 is inserted back into the liner 1 and the packer 6 is set, completing the well completion work.

[0063] When sidetracking is required or well workover is needed in the upper part, the packer 6 is released, and then the second tubing 7 is pulled up directly from the wellhead position. The second tubing 7, inner cylinder 52 and first tubing 4 are pulled out of the well. Then the outer cylinder 51 and easy-drill pipe 8 left in the well are drilled out, thereby exposing the open hole section 101. Sidetracking tools are then lowered to sidetrack the open hole section 101.

[0064] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0065] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and does not constitute any limitation on this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A double-tube release device for easy side-drilling, characterized in that, include: The outer cylinder (51) has a groove (511) on its inner wall, and the lower end of the outer cylinder (51) is connected to an easy-drill pipe (8). An inner cylinder (52) is coaxially arranged inside the outer cylinder (51). A stop (55) is provided on the side wall of the inner cylinder (52) in a radially movable manner. A backlash groove (521) is provided on the inner wall of the inner cylinder (52). The lower end of the inner cylinder (52) is connected to a first oil pipe (4). The outer diameter of the first oil pipe (4) is smaller than the inner diameter of the easy-drill pipe (8). A piston assembly (54) is coaxially arranged in the inner cylinder (52) by a shear pin (53). A groove (540) is provided on the outer wall of the piston assembly (54). A retaining ring (543) is provided on the outer wall of the piston assembly (54) to be adapted to the retaining groove (521). In the first state, the piston assembly (54) radially abuts against the inner side of the stop (55), such that the outer side of the stop (55) is connected to the slot (511); In the second state, the piston assembly (54) moves relative to the inner cylinder (52) to the position where the groove (540) reaches the stop (55), so that the stop (55) can move radially inward to disengage from the slot (511).

2. The dual-tube release device according to claim 1, characterized in that, A lower connector (56) for connecting the first oil pipe (4) is provided at the lower end of the inner cylinder (52). The inner diameter of the upper end of the lower connector (56) is smaller than the inner diameter of the inner cylinder (52). The outer wall of the upper end of the piston assembly (54) is sealed with the inner wall of the inner cylinder (52), and the outer wall of the lower end of the piston assembly (54) is sealed with the inner wall of the lower connector (56), thereby forming a pressure differential surface at both ends of the piston assembly (54) in the axial direction.

3. The dual-tube release device according to claim 2, characterized in that, The piston assembly (54) includes an upper piston (541) and a lower piston (542) arranged coaxially from top to bottom. The upper end of the upper piston (541) is sealed to the inner cylinder (52). The outer wall of the lower end of the upper piston (541) is sealed to the inner wall of the upper end of the lower piston (542) by means of a threaded connection. The outer wall of the upper end of the lower piston (542) is sealed to the inner cylinder (52). The outer wall of the lower end of the lower piston (542) is sealed to the lower connector (56).

4. The dual-tube release device according to claim 3, characterized in that, The upper piston (541) and the lower piston (542) are coaxially connected by a threaded connection, and threadlocker is applied to the connection between the upper piston (541) and the lower piston (542).

5. The dual-tube release device according to claim 3, characterized in that, The stop (55) is located above the lower piston (542), and the groove (540) is provided on the inner wall of the upper piston (541).

6. The dual-tube release device according to claim 5, characterized in that, The stop member (55) includes a support ring (551) and a key block (552). The support ring (551) is coaxially disposed on the outside of the upper piston (541), and the key block (552) is radially movable on the side wall of the outer cylinder (51). In the first state, the inner side of the key block (552) abuts radially against the support ring (551); In the second state, the key block (552) moves upward relative to the support ring (551) and disengages from the support ring (551).

7. The dual-tube release device according to claim 3, characterized in that, High-temperature grease is provided in the first cavity (58) formed between the upper piston (541), the inner cylinder (52) and the lower piston (542) and the second cavity (59) formed between the lower piston (542), the inner cylinder (52) and the lower connector (56).

8. The dual-tube release device according to claim 7, characterized in that, Connection holes (50) are provided on the side walls of the outer cylinder (51) and the inner cylinder (52) to connect the first cavity (58) and the second cavity (59) to the outside world respectively.

9. The double-tube release device according to any one of claims 1 to 8, characterized in that, The outer cylinder (51) includes a first outer shell (513) and a second outer shell (514) arranged coaxially from top to bottom. The slot (511) is provided on the inner wall of the first outer shell (513), and the lower end of the second outer shell (514) is used to connect the easy-drill pipe (8).

10. The dual-tube release device according to claim 9, characterized in that, A fastening pin (93) is provided between the first housing (513) and the second housing (514).

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