Five-stage multilateral well completion tool and method

Abstract

The invention belongs to the technical field of petroleum well completion, and particularly relates to a five-stage multilateral well completion tool and method. The five-stage multilateral well completion tool comprises a well hole connector; the double-pipe integrated positioning tool is internally provided with two channels used for installing branch oil pipes, the two channels communicate with the main well hole and the two branch well holes correspondingly, the double-pipe integrated positioning tool is provided with a first spiral guide face, and the well hole connector is provided with a second spiral guide face; the locking mechanism is fixedly connected with the double-pipe integrated positioning tool, in the well entering stage, the locking mechanism locks the double-pipe integrated positioning tool and the branch oil pipe, and after the double-pipe integrated positioning tool enters the well in place, the locking mechanism unlocks the double-pipe integrated positioning tool and the branch oil pipe; and the rotatable three-way connector connects the main oil pipe located on the upper portion with the two branch oil pipes located on the lower portion, and the rotatable three-way connector is constructed to enable the two branch oil pipes to rotate relative to the main oil pipe.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum well completion, and in particular relates to a five-level branch well completion tool and a five-level branch well completion method. Background Art

[0002] As an extension and development of horizontal well technology, branch well technology can increase the oil leakage area of ​​a single well, effectively tap the potential of remaining oil, increase recovery rate, and improve the effect of oil field development. It has become an advanced technology for oil and gas field development. The four-level branch well technology can meet the development requirements of most oil fields, but the wellbore connection part does not have pressure sealing properties and cannot fully meet the development needs of some oil and gas reservoirs. The five-level branch well technology has good pressure sealing properties at the wellbore connection, and is more adaptable than the four-level branch well technology. It provides an effective means for the continuous, economical and effective development of reservoirs that are prone to water and sand, layered reservoirs, marginal reservoirs, fault block reservoirs and mid- and late-stage reservoirs.

[0003] Chinese patent document CN112627777A discloses a selectively re-entrant branch well double-tube completion string system, construction and oil production method. The system includes an electric submersible pump string string, a production packer assembly, a selective re-entry tool and a double-tube sealing tool assembly. The lower end of the electric submersible pump string string is connected to the upper end of the production packer assembly; the selective re-entry tool is an inverted "Y"-shaped pipeline structure, the upper part of the inverted "Y"-shaped pipeline is the main oil pipe, and the lower part is the main oil pipe and the auxiliary oil pipe respectively; the main oil pipe forms a main wellbore flow channel inside, and the auxiliary oil pipe forms a branch wellbore flow channel inside; the upper end of the main oil pipe is connected to the lower end of the production packer assembly; the double-tube sealing tool assembly includes a main wellbore sealing tool and a branch wellbore sealing tool; the main wellbore sealing tool is connected to the lower end of the main oil pipe, and the branch wellbore sealing tool is connected to the lower end of the auxiliary oil pipe.

[0004] The patent document uses a selective re-entry tool, a main wellbore production pipe string, a branch wellbore production pipe string and a double-tube sealing tool assembly to achieve pressure sealing at the window part, but it is difficult to implement: (1) It does not address the problem of how the main wellbore production pipe string and the branch wellbore production pipe string can be inserted into the corresponding main wellbore and branch wellbore respectively; (2) It does not address the problem of the oil injection pipe being connected to both the double-tube packer and the double-tube sealing tool assembly, the auxiliary oil pipe being connected to both the double-tube packer and the double-tube sealing tool assembly, and the main and auxiliary oil pipes being connected to the double-tube packer and the double-tube sealing tool assembly at the same time.

[0005] Chinese patent document CN112627778A discloses a branch well double-tube completion tubing system and its construction method and oil production method, wherein the system includes an electric submersible pump tubing string, a production packer assembly, a double-tube packer and a double-tube sealing tool assembly arranged in sequence from top to bottom, the electric submersible pump tubing string, the production packer assembly and the double-tube packer are connected through the branch wellbore production tubing string, the double-tube packer is connected to the double-tube sealing tool assembly through the main wellbore production tubing string and the branch wellbore production tubing string, and a sliding sleeve and a landing joint are arranged in sequence from top to bottom on the branch wellbore production tubing string located between the production packer assembly and the double-tube packer, the sliding sleeve is used to connect or close the main wellbore production flow channel, and the landing joint is used to connect or close the branch wellbore production flow channel.

[0006] This patent document uses a double-tube packer, a main wellbore production pipe string, a branch wellbore production pipe string and a double-tube sealing tool assembly to achieve pressure sealing at the window part, but it is difficult to implement: (1) It does not address the problem of how the main wellbore production pipe string and the branch wellbore production pipe string can be inserted into the corresponding main wellbore and branch wellbore respectively; (2) It does not address the problem of the main oil pipe being connected to both the double-tube packer and the double-tube sealing tool assembly, the auxiliary oil pipe being connected to both the double-tube packer and the double-tube sealing tool assembly, and the main and auxiliary oil pipes being connected to the double-tube packer and the double-tube sealing tool assembly at the same time. Summary of the invention

[0007] In view of the technical problems mentioned above, the present invention aims to provide a five-level branch well completion tool, which can solve at least one of the above problems.

[0008] The present invention also proposes a five-level branch well completion method, which can solve at least one of the above problems.

[0009] According to the present invention, a five-level branch well completion tool is provided, comprising:

[0010] A double-tube integrated positioning tool, in which two channels for installing branch oil pipes are arranged;

[0011] A locking mechanism, which is fixedly connected to the double-tube integrated positioning tool. During the well entry stage, the locking mechanism locks the double-tube integrated positioning tool with the branch oil pipe. After the double-tube integrated positioning tool is in place in the well, the locking mechanism is unlocked;

[0012] A rotatable three-way joint connects a main oil pipe located above and two branch oil pipes located below, and the rotatable three-way joint is configured to enable the two branch oil pipes to rotate relative to the main oil pipe.

[0013] In a preferred embodiment, the locking mechanism includes a locking outer cylinder fixedly connected to the double-tube integrated positioning tool, and a one-way locking assembly is provided on the inner wall of the locking outer cylinder, and the one-way locking assembly is configured to enable the branch oil pipe to move unidirectionally in the locking mechanism.

[0014] In a preferred embodiment, the one-way locking assembly includes a locking ring arranged on the inner wall of the locking outer cylinder, the upper end face of the locking ring is set as an inclined surface, the lower end face of the locking ring is set as a plane, and a limiting groove for adapting to the locking ring is set on the outer wall of the branch oil pipe.

[0015] In a preferred embodiment, the locking outer cylinder comprises an upper locking sleeve and a lower locking sleeve that are coaxially fixedly connected, a limiting groove is formed at the joint between the upper locking sleeve and the lower locking sleeve, and the locking ring is arranged in the limiting groove.

[0016] In a preferred embodiment, the rotatable three-way joint comprises:

[0017] A double-turn single-flow channel body, wherein the lower end of the double-turn single-flow channel body is provided with two small circular holes for connecting branch oil pipes;

[0018] A coupling, the upper end of which is used to connect the main oil pipe;

[0019] A rotating assembly connects the double-turn single-channel body and the coupling, and the rotating assembly is configured to enable the double-turn single-channel body and the coupling to rotate relative to each other.

[0020] In a preferred embodiment, the rotating assembly comprises:

[0021] A mandrel coaxially connected to the lower end of the coupling;

[0022] A diameter expansion short section is sealed and rotatably sleeved on the outside of the spindle, and the lower end of the diameter expansion short section is coaxially connected with the double-rotation single-channel body.

[0023] In a preferred embodiment, a raised section is coaxially fixed on the outer wall of the mandrel, a pressure cap is coaxially sleeved on the outer wall of the mandrel, the pressure cap is coaxially fixed with the expansion short section, and the raised section is located at the joint between the pressure cap and the expansion short section.

[0024] In a preferred embodiment, a bearing is sleeved on the exterior of the spindle, and two bearings are respectively arranged at the upper and lower ends of the raised section.

[0025] In a preferred embodiment, the lower end of the rotatable three-way joint is connected to the branch oil pipe through a flexible joint, and the flexible joint includes an upper joint and a lower joint that are coaxially rotating and sealed, the upper joint is fixedly connected to the rotatable three-way joint, and the lower joint is connected to the branch oil pipe.

[0026] According to the present invention, a five-level branch well completion method is also provided, and the five-level branch well completion tool provided by the present invention is used to perform completion construction, comprising the following steps:

[0027] Step 1: placing an anchor seal cylinder in the wellbore;

[0028] Step 2, inserting the wellbore connector;

[0029] Step 3: lowering the dual-tube integrated positioning tool and branch oil pipe;

[0030] Step 4, lower the rotatable three-way joint;

[0031] Step five: lower the production packer.

[0032] Compared with the prior art, the advantages of the present application are as follows.

[0033] The present invention provides a completion tool based on a four-level branch well system to achieve pressure sealing of the wellbore connection part and upgrade the four-level branch well system to a five-level branch well system.

[0034] The five-level branch well completion tool provided by the present invention can realize automatic positioning, so that the sealing plug on the branch oil pipe is aligned with the wellbore;

[0035] The flexible joint provided by the present invention effectively solves the problem of connecting two oil pipes to the rotatable three-way joint at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be described below with reference to the accompanying drawings.

[0037] Figure 1 A schematic diagram of an embodiment of a four-level branch well;

[0038] Figure 2a is a schematic diagram of an embodiment of a wellbore connector of the present invention;

[0039] Figure 2b For the present invention Figure 2a A schematic diagram of a top view structure;

[0040] Figure 3 A schematic diagram of an embodiment of a five-stage branch well completion tool after completion;

[0041] Figure 4 is a schematic diagram of an embodiment of a rotatable three-way joint of the present invention;

[0042] Figure 5 is a schematic diagram of an embodiment of a flexible joint of the present invention;

[0043] Figure 6 A schematic diagram of an embodiment of a double-tube integrated positioning tool of the present invention;

[0044] Figure 7 is a schematic diagram of an embodiment of the locking mechanism of the present invention;

[0045] Figure 8 It is a schematic diagram of an embodiment of the dual-tube integrated positioning tool of the present invention after being in place in a wellbore connector.

[0046] In the figure: 1. Production packer; 2. First branch wellbore flexible joint; 3. Second branch wellbore flexible joint; 4. Dual-tube integrated positioning tool; 5. Second branch wellbore sealing plug; 6. Second branch wellbore anchoring seal assembly; 7. Second branch wellbore anchoring seal cylinder; 8. Lower hanger; 9. Main oil pipe; 10. Rotatable tee joint; 11. Main casing; 12. Upper hanger; 13. Second unhooked oil pipe; 14. First unhooked oil pipe ; 15, wellbore connector; 16, cement ring; 17, first branch wellbore sealing plug; 18, first branch wellbore anchoring seal assembly; 19, first branch wellbore anchoring seal cylinder; 20, first branch wellbore casing string; 21, first branch wellbore; 22, second branch wellbore casing string; 23, second branch wellbore; 151, wellbore connector upper end; 152, second spiral guide surface; 153, wellbore connector lower end; 154, side opening mouth; 100, rotating assembly; 101, coupling; 102, first sealing ring; 103, mandrel; 104, pressure cap; 105, bearing; 106, second sealing ring; 107, expansion nipple; 108, double-turn single-channel body; 109, third sealing ring; 1031, raised section; 1081, large circular hole; 1082, small circular hole; 201, upper joint; 202, suspension tube; 203, copper ring; 204, fourth sealing ring; 2 05, lower joint; 2011, outer cylindrical surface protrusion; 41, first branch channel; 42, second branch channel; 43, first spiral guide surface; 171, upper tubular column of first branch wellbore sealing plug; 172, locking mechanism; 1721, upper locking sleeve; 1722, lower locking sleeve; 1723, limiting groove; 1724, locking ring; 1725, locking outer tube; 1726, one-way locking assembly; 1000, five-level branch well completion tool.

[0047] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0048] The present invention will be described below with reference to the accompanying drawings.

[0049] It should be noted that, in the present application, the direction of the five-level branch well completion tool 1000 according to the present invention close to the wellhead after entering the well is described as "up", "front" or similar terms, and the direction away from the wellhead is described as "down", "back" or similar terms.

[0050] Figure 1 The structure of the four-level branch wells is shown. Figure 1 As shown, the four-level branch well includes a main wellbore and a first branch wellbore 21 and a second branch wellbore 23 connected to the lower end of the main wellbore. A main casing 11 is coaxially arranged in the main wellbore, a second branch wellbore casing string 22 is coaxially arranged in the first branch wellbore 21 through a cement ring 16, the upper end of the second branch wellbore casing string 22 is connected to the main casing 11 through a lower hanger 8, and a first branch wellbore casing string 20 is coaxially arranged in the second branch wellbore 23 through a cement ring 16. A wellbore connector 15 is arranged in the main casing 11 through an upper hanger 12, one end of the wellbore connector 15 is connected to the main casing 11, and the other end is coaxially connected to the first branch wellbore casing string 20, and the side wall of the wellbore connector 15 is connected to the second branch wellbore 23.

[0051] According to the present invention, the five-stage branch well completion tool 1000 includes a wellbore connector 15 , a dual-tube integrated positioning tool 4 , a locking mechanism 172 and a rotatable three-way joint 10 .

[0052] The upper end of the wellbore connector 15 is connected to the main casing 11, the lower end of the wellbore connector 15 is connected to one of the branch wellbores, and the side wall of the wellbore connector 15 is connected to the other branch wellbore. Specifically, Figure 2a and Figure 2b The structure of the wellbore connector 15 of the present invention is shown. In this embodiment, the wellbore connector 15 is configured as a cylindrical structure. Figure 1 The upper end 151 of the wellbore connector is connected to the upper hanger 12, and the lower end 153 of the wellbore connector is connected to the first branch wellbore casing string 20. A side opening 154 is provided on the side wall of the wellbore connector 15, and the side opening 154 is connected to the second branch wellbore 23. A second spiral guide surface 152 is provided at the lower part of the inner wall of the wellbore connector 15, and the second spiral guide surface 152 is constructed to be symmetrical with respect to a plane passing through the central axis of the wellbore connector 15.

[0053] In a specific embodiment, Figure 6As shown, two channels for installing branch oil pipes (i.e., the first unhooked oil pipe 14 and the second unhooked oil pipe 13) are provided in the double-tube integrated positioning tool 4, and the two channels respectively connect the main wellbore with the two branch wellbores. Specifically, a first branch channel 41 and a second branch channel 42 are provided in the double-tube integrated positioning tool 4, wherein the first branch channel 41 connects the axial ends of the double-tube integrated positioning tool 4, and the second branch channel 42 connects the axial upper end of the double-tube integrated positioning tool 4 with the side wall. A first spiral guide surface 43 is provided at the lower part of the outer wall of the double-tube integrated positioning tool 4, and the shape of the first spiral guide surface 43 matches the shape of the second spiral guide surface 152. When the double-tube integrated positioning tool 4 enters the well and enters the wellbore connector 15, the first spiral guide surface 43 and the second spiral guide surface 152 cooperate with each other, so that the lower end of the second branch channel 42 of the double-tube integrated positioning tool 4 is aligned with the side opening 154 of the wellbore connector 15.

[0054] According to the present invention, the locking mechanism 172 is fixedly connected to the double-tube integrated positioning tool 4. During the well entry stage, the locking mechanism 172 locks the double-tube integrated positioning tool 4 with the branch oil pipe. After the double-tube integrated positioning tool 4 is in place in the well, the locking mechanism 172 is unlocked.

[0055] In a specific embodiment, Figure 7 As shown, the locking mechanism 172 includes a locking outer cylinder 1725 fixedly connected to the double-tube integrated positioning tool 4, and a one-way locking assembly 1726 is arranged on the inner wall of the locking outer cylinder 1725, and the one-way locking assembly 1726 is configured to make the branch oil pipe move unidirectionally in the locking mechanism 172. Further, the one-way locking assembly 1726 includes a locking ring 1724 arranged on the inner wall of the locking outer cylinder 1725, the upper end surface of the locking ring 1724 is arranged as an inclined surface, and the lower end surface of the locking ring 1724 is arranged as a plane.

[0056] A limiting groove 1723 for matching with the locking ring 1724 is provided on the outer wall of the branch oil pipe. According to the present invention, the locking outer cylinder 1725 includes an upper locking sleeve 1721 and a lower locking sleeve 1722 which are coaxially fixedly connected. An external thread is provided at the lower end of the upper locking sleeve 1721, and an internal thread is provided at the upper end of the lower locking sleeve 1722, and the two are connected to each other by threaded connection. The limiting groove 1723 is provided on the inner wall of the lower locking sleeve 1722. Specifically, the lower end of the upper locking sleeve 1721 constitutes the upper end surface of the limiting groove 1723, and the limiting groove 1723 is formed at the joint of the upper locking sleeve 1721 and the lower locking sleeve 1722. After the lower locking sleeve 1722 is separated from the upper locking sleeve 1721, the locking ring 1724 can enter the limiting groove 1723 from top to bottom.

[0057] In this embodiment, the lower end of the lower locking sleeve 1722 is coaxially fixed to the upper end of the first branch channel 41 of the double-tube integrated positioning tool 4. During the process of entering the well, the double-tube integrated positioning tool 4 is locked on the first uncoupled oil pipe 14 through the locking mechanism 172. Specifically, Figure 7 As shown, the lower end of the first uncoupled tubing 14 is the first branch wellbore sealing plug 17, and a part of the first branch wellbore sealing plug 17 is shown in the figure, namely, the upper tubing string 171 of the first branch wellbore sealing plug, and a groove for matching with the locking ring 1724 is provided on the outer wall of the upper tubing string 171 of the first branch wellbore sealing plug. Since the lower end surface of the locking ring 1724 is set as a plane, and the inner side of the upper end is set as an inclined surface, when the double-tube integrated positioning tool 4 is locked on the first uncoupled tubing 14 through the locking mechanism 172, the lower end plane of the locking ring 1724 prevents the first uncoupled tubing 14 from moving upward relative to the locking mechanism 172, thereby preventing the two from separating until the double-tube integrated positioning tool 4 enters the wellbore connector 15 and is in place, as shown in FIG. Figure 8 When the dual-tube integrated positioning tool 4 enters the wellbore connector 15 and is in place, the first uncoupled oil pipe 14 continues to move downward, and the inclined surface at the upper end of the locking ring 1724 cannot prevent the first uncoupled oil pipe 14 from moving downward, so that the first branch wellbore sealing plug 17 of the first uncoupled oil pipe 14 can move downward and connect with the first branch wellbore anchoring sealing cylinder 19.

[0058] According to the present invention, Figure 3 As shown, the rotatable three-way joint 10 connects the main oil pipe located at the top and the two branch oil pipes located at the bottom. The rotatable three-way joint 10 is configured to enable the two branch oil pipes to rotate relative to the main oil pipe.

[0059] In a specific embodiment, Figure 4 As shown, the rotatable three-way joint 10 includes a double-turn single-flow channel body 108, a coupling 101 and a rotating assembly 100. The lower end of the double-turn single-flow channel body 108 is provided with two small round holes 1082 for connecting branch oil pipes, and the upper end of the coupling 101 is used to connect the main oil pipe. Figure 3, the two small circular holes 1082 at the lower end of the double-turn single-flow channel body 108 are connected to the first uncoupled oil pipe 14 and the second uncoupled oil pipe 13 respectively, and the upper end of the coupling 101 is used to connect the main oil pipe 9. The rotating assembly 100 connects the double-turn single-flow channel body 108 and the coupling 101, and the rotating assembly 100 is configured to enable the double-turn single-flow channel body 108 and the coupling 101 to rotate relative to each other. Under this setting, when the first spiral guide surface 43 of the double-tube integrated positioning tool 4 is axially rotated and positioned under the action of the second spiral guide surface 152, the first uncoupled oil pipe 14 and the second uncoupled oil pipe 13 will inevitably rotate together, and the rotating assembly 100 can enable the first uncoupled oil pipe 14 and the second uncoupled oil pipe 13 to rotate relative to the main oil pipe 9, thereby preventing the first uncoupled oil pipe 14 and the second uncoupled oil pipe 13 from being entangled with each other like twisting a knot during the rotation process.

[0060] In a specific embodiment, the rotating assembly 100 includes a mandrel 103 coaxially connected to the lower end of the coupling 101 by threaded connection, and a first sealing ring 102 is provided between the mandrel 103 and the coupling 101. The rotating assembly 100 also includes an expansion nipple 107 sealingly and rotatably sleeved on the outside of the mandrel 103, and a second sealing ring 106 is provided between the expansion nipple 107 and the mandrel 103. The lower end of the expansion nipple 107 is coaxially connected to the upper end of the double-turn single-channel body 108 by threaded connection, and a third sealing ring 109 is provided between the expansion nipple 107 and the double-turn single-channel body 108. The fluid in the well passes through the first couplingless oil pipe 14 and the second couplingless oil pipe 13 connected below the double-turn single-channel body 108 in turn, through the small circular hole 1082, the large circular hole 1081, the inner cavity of the core shaft 103, the inner cavity of the coupling 101, and finally flows to the ground from the main oil pipe 9 connected above the coupling 101.

[0061] Furthermore, a raised section 1031 is coaxially fixed to the outer wall of the mandrel 103, and a pressure cap 104 is coaxially sleeved on the outer wall of the mandrel 103. The inner diameter of the pressure cap 104 is smaller than the outer diameter of the raised section 1031, and the pressure cap 104 is located above the raised section 1031. The inner diameter of the upper part of the expansion short section 107 is larger than the outer diameter of the raised section 1031, the inner diameter of the middle part of the expansion short section 107 is smaller than the outer diameter of the raised section 1031, the middle part of the expansion short section 107 is located below the raised section 1031, and the upper part of the expansion short section 107 extends upward and exceeds the raised section 1031, and the upper part of the expansion short section 107 exceeding the raised section 1031 is fixedly connected to the pressure cap 104 by threaded connection. In this way, the pressure cap 104 is coaxially fixed with the expansion short section 107, and the raised section 1031 is located at the joint between the pressure cap 104 and the expansion short section 107. The pressure cap 104 and the expansion short section 107 can rotate axially relative to the core shaft 103, and thus the double-turn single flow channel body 108 can rotate relative to the core shaft 103.

[0062] In a preferred embodiment, a bearing 105 is sleeved on the outside of the spindle 103, and two bearings 105 are respectively arranged at the upper and lower ends of the raised section 1031. The upper end surface of the bearing located above the raised section 1031 abuts against the lower end surface of the pressure cap 104, and the lower end surface of the bearing located below the raised section 1031 abuts against the expansion short section 107, and the outer walls of the two bearings 105 abut against the inner wall of the expansion short section 107. By providing the bearing 105, the pressure cap 104 and the expansion short section 107 can be more smoothly rotated relative to the spindle 103 axially.

[0063] According to the present invention, in a preferred embodiment, the lower end of the rotatable tee joint 10 is connected to the branch oil pipe via a flexible joint. The flexible joint enables the branch oil pipe to rotate relative to the rotatable tee joint 10.

[0064] Specifically, Figure 3 As shown, the first branch wellbore flexible joint 2 and the second branch wellbore flexible joint 3 are used to connect the first uncoupled oil pipe 14 and the second uncoupled oil pipe 13 respectively. The specific structures of the two flexible joints are the same. The first branch wellbore flexible joint 2 is taken as an example for description. Figure 5 As shown, the first branch wellbore flexible joint 2 includes an upper joint 201 and a lower joint 205 that are coaxially rotatably sealed, the upper end of the upper joint 201 is sealedly connected to one of the small round holes 1082 of the rotatable tee joint 10, and the lower joint 205 is connected to the first unhooked oil pipe 14. Through this arrangement, when the two branch oil pipes follow the dual-tube integrated positioning tool 4 to rotate and orient, the two branch oil pipes can have a higher degree of freedom relative to the rotatable tee joint 10, which is beneficial to the completion construction.

[0065] Furthermore, an outer cylindrical protrusion 2011 is provided on the outer wall of the upper joint 201. A suspension tube 202 is rotatably sleeved on the upper joint 201, the inner diameter of the suspension tube 202 is smaller than the outer diameter of the outer cylindrical protrusion 2011, and the suspension tube 202 is located above the outer cylindrical protrusion 2011. The inner diameter of the middle part of the lower joint 205 is smaller than the outer diameter of the outer cylindrical protrusion 2011, and is located below the outer cylindrical protrusion 2011. The inner diameter of the upper part of the lower joint 205 is larger than the outer diameter of the outer cylindrical protrusion 2011, and the upper part of the lower joint 205 extends upward beyond the outer cylindrical protrusion 2011, and is fixed to the suspension tube 202 by threaded connection. A fourth sealing ring 204 is provided between the lower joint 205 and the upper joint 201.

[0066] In a preferred embodiment, left and right copper rings 203 are also sleeved on the upper joint 201, and the two copper rings 203 are arranged at the upper and lower ends of the outer cylindrical protrusion 2011, and the upper end surface of the copper ring 203 located at the upper end abuts against the lower end surface of the suspension tube 202, and the lower end surface of the copper ring 203 located at the lower end abuts against the lower joint 205, and the outer walls of the two copper rings 203 abut against the inner wall of the lower joint 205. By arranging the copper rings 203, the rotation of the lower joint 205 relative to the upper joint 201 is smoother.

[0067] In a preferred embodiment, the first branch wellbore flexible joint 2 and the second branch wellbore flexible joint 3 are staggered in the longitudinal direction, so as to prevent the two from squeezing each other in the lateral direction.

[0068] In one embodiment of the present invention, a five-level branch well completion method is provided, such as Figure 3 and Figure 8 As shown, the following steps are included:

[0069] (1) lowering the first branch wellbore anchoring seal cylinder 19 into the first branch wellbore 21, so that the first branch wellbore anchoring seal cylinder 19 is seated and sealed in the first branch wellbore casing string 20;

[0070] (2) lowering the second branch wellbore anchoring seal cylinder 7 into the second branch wellbore 23, so that the second branch wellbore anchoring seal cylinder 7 is seated and sealed on the main casing 11 in the second branch wellbore 23;

[0071] (3) Lowering the dual-tube integrated positioning tool 4, the first uncoupled tubing 14 and the second uncoupled tubing 13:

[0072] Insert the first branch wellbore sealing plug 17 into the first branch channel 41 of the double-tube integrated positioning tool 4, and Figure 7 The locking mechanism 172 on the upper part of the first branch wellbore sealing plug 17 is connected to the upper end of the first branch channel 41 of the double-tube integrated positioning tool 4, the second branch wellbore sealing plug 5 is inserted into the second branch channel 42 of the double-tube integrated positioning tool 4, the double-tube integrated positioning tool 4 is seated on the wellhead using a double-tube elevator and a double-tube chuck, and then the second uncoupled oil pipe 13 is connected to the second branch wellbore sealing plug 5, and then the first uncoupled oil pipe 14 is connected to the first branch wellbore sealing plug 17, and several uncoupled oil pipes are connected in sequence and lowered into the well;

[0073] (4) Lowering the rotatable three-way joint 10, the first branch wellbore flexible joint 2 and the second branch wellbore flexible joint 3:

[0074] Connect the first branch wellbore flexible joint 2 to the bottom of the rotatable tee joint 10, connect the second branch wellbore flexible joint 3 to the bottom of the rotatable tee joint 10, lift the rotatable tee joint 10 with a common elevator, first connect the second branch wellbore flexible joint 3 to the second uncoupled oil pipe 13, and then connect the first branch wellbore flexible joint 2 to the first uncoupled oil pipe 14;

[0075] It should be noted that: since the lower joint 205 of the first branch wellbore flexible joint 2 can rotate independently relative to the upper joint 201, the first branch wellbore flexible joint 2 can be connected to the uncoupled oil pipe 14 and the second branch wellbore flexible joint 3 can be connected to the uncoupled oil pipe 13 by simply rotating the lower joint 205, thereby facilitating the connection of the uncoupled oil pipe with the rotatable tee joint 10;

[0076] (5) Lowering the production packer 1:

[0077] After several main oil pipes 9 are connected to the rotatable tee joint 10 and seated at the wellhead, the running tool of the production packer 1 is connected to the production packer 1, and the lower end of the production packer 1 is connected to the main oil pipe 9 seated at the wellhead. The production packer 1 and its lower tool string are lowered by connecting the drill pipe or oil pipe to the upper end of the running tool;

[0078] (6) Double-tube integrated positioning tool 4 is in place:

[0079] After the double-tube integrated positioning tool 4 is lowered into the wellbore connector 15, the first spiral guide surface 43 at the lower end of the double-tube integrated positioning tool 4 contacts the second spiral guide surface 152 of the wellbore connector 15, and a certain drilling pressure is applied. The whole composed of the double-tube integrated positioning tool 4, the first branch wellbore sealing plug 17, the second branch wellbore sealing plug 5, the second unhooked oil pipe 13, the first unhooked oil pipe 14, the first branch wellbore flexible joint 2, the second branch wellbore flexible joint 3, the double-rotation single-flow channel body 108 of the rotatable tee joint 10, the enlarged diameter short section 107 of the rotatable tee joint 10 and the pressure cap 104 of the rotatable tee joint 10 will rotate relative to the mandrel 103 of the rotatable tee joint 10 and the pipe string above. After the double-tube integrated positioning tool 4 is in place, its first branch channel 41 is connected to the first branch wellbore 21, and the second branch channel 42 is connected to the second branch wellbore 23;

[0080] (7) Insert the first branch wellbore sealing plug 17 into the first branch wellbore anchoring sealing cylinder 19, and insert the second branch wellbore sealing plug 5 into the second branch wellbore anchoring sealing cylinder 7:

[0081] Continue to apply a certain drilling pressure, the locking mechanism 172 on the upper part of the first branch wellbore sealing plug 17 is unlocked, the first branch wellbore sealing plug 17 enters the first branch wellbore 21, the second branch wellbore sealing plug 5 enters the main casing 11, and the wellhead continues to connect and lower the drill pipe and oil pipe until the first branch wellbore sealing plug 17 is inserted into the first branch wellbore anchoring seal tube 19, and the second branch wellbore sealing plug 5 is inserted into the second branch wellbore anchoring seal tube 7.

[0082] (8) The production packer 1 is hung and sealed on the inner wall of the main casing 11.

[0083] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0084] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0085] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0086] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A five-stage branch well completion tool, characterized in that: The five-level branch well completion tools include: A double-tube integrated positioning tool (4), wherein two channels for installing branch oil pipes are arranged inside the double-tube integrated positioning tool (4); A locking mechanism (172), the locking mechanism (172) being fixedly connected to the double-tube integrated positioning tool (4), wherein during the well entry phase, the locking mechanism (172) locks the double-tube integrated positioning tool (4) with the branch oil pipe, and after the double-tube integrated positioning tool (4) is in place in the well, the locking mechanism (172) is unlocked; A rotatable three-way joint (10) connects a main oil pipe located above and two branch oil pipes located below. The rotatable three-way joint (10) is configured to enable the two branch oil pipes to rotate relative to the main oil pipe.

2. The five-level branch well completion tool according to claim 1, characterized in that: The locking mechanism (172) comprises a locking outer cylinder (1725) fixedly connected to the double-tube integrated positioning tool (4), and a one-way locking component (1726) is provided on the inner wall of the locking outer cylinder (1725). The one-way locking component (1726) is configured to enable the branch oil pipe to move unidirectionally within the locking mechanism (172).

3. The five-level branch well completion tool according to claim 2, characterized in that: The one-way locking assembly (1726) includes a locking ring (1724) arranged on the inner wall of the locking outer cylinder (1725), the upper end surface of the locking ring (1724) is arranged as an inclined surface, the lower end surface of the locking ring (1724) is arranged as a plane, and a limiting groove (1723) for adapting to the locking ring (1724) is arranged on the outer wall of the branch oil pipe.

4. The five-level branch well completion tool according to claim 3, characterized in that: The locking outer cylinder (1725) comprises an upper locking sleeve (1721) and a lower locking sleeve (1722) which are coaxially fixedly connected, a limiting groove (1723) is formed at the joint between the upper locking sleeve (1721) and the lower locking sleeve (1722), and the locking ring (1724) is arranged in the limiting groove (1723).

5. The five-level branch well completion tool according to claim 1, characterized in that: The rotatable three-way joint (10) comprises: A double-turn single-flow channel body (108), wherein the lower end of the double-turn single-flow channel body (108) is provided with two small circular holes (1082) for connecting branch oil pipes; A coupling (101), the upper end of which is used to connect to the main oil pipe; A rotating assembly (100) connects the double-turn single-channel body (108) and the coupling (101), and the rotating assembly (100) is configured to enable the double-turn single-channel body (108) and the coupling (101) to rotate relative to each other.

6. The five-stage branch well completion tool according to claim 5, characterized in that: The rotating assembly (100) comprises: A mandrel (103) coaxially connected to the lower end of the coupling (101); A diameter expansion short section (107) is sealed and rotatably sleeved on the outside of the spindle (103), and the lower end of the diameter expansion short section (107) is coaxially connected to the double-rotation single-channel body (108).

7. The five-stage branch well completion tool according to claim 6, characterized in that: A raised section (1031) is coaxially fixed on the outer wall of the mandrel (103), a pressure cap (104) is coaxially sleeved on the outer wall of the mandrel (103), the pressure cap (104) is coaxially fixed with the expansion short section (107), and the raised section (1031) is located at the joint between the pressure cap (104) and the expansion short section (107).

8. The five-stage branch well completion tool according to claim 7, characterized in that: A bearing (105) is sleeved on the outside of the spindle (103), and two bearings (105) are respectively arranged at the upper and lower ends of the raised section (1031).

9. The five-stage branch well completion tool according to claim 1, characterized in that: The lower end of the rotatable three-way joint (10) is connected to the branch oil pipe via a flexible joint, and the flexible joint comprises an upper joint and a lower joint that are coaxially rotatably sealed, the upper joint is fixedly connected to the rotatable three-way joint (10), and the lower joint is connected to the branch oil pipe.

10. A five-level branch well completion method, characterized in that: The well completion construction is carried out using the five-level branch well complete well tool according to any one of claims 1 to 9, comprising the following steps: Step 1: placing an anchor seal cylinder in the wellbore; Step 2, inserting the wellbore connector; Step 3: lowering the dual-tube integrated positioning tool and branch oil pipe; Step 4: lower the rotatable three-way joint; Step five: lower the production packer.

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