A window tool for a multilateral well and a method of completing a multilateral well

Abstract

The application provides a window tool for a branch well, comprising: a main wellbore connector, which comprises a first connector body and a positioning plug, and is provided with a first pre-open window; a branch wellbore connector, which comprises a second connector body, and is provided with a second pre-open window; wherein the main wellbore connector can be connected with an anchor packer at the lower part of the branch well window through the positioning plug and automatically rotated and oriented, so that the first pre-open window is aligned with the branch wellbore; the branch wellbore connector can enter the branch wellbore through the first pre-open window, and the branch wellbore connector is configured to be automatically oriented with the main wellbore connector, so that the second pre-open window is coincided with the first pre-open window and the main wellbore is penetrated, thereby the main wellbore or the branch wellbore can be back-joined through the main wellbore connector or the branch wellbore connector, so that the main wellbore or the branch wellbore can be fractured. The application also provides a branch well completion method.

Description

Technical Field

[0001] This invention belongs to the field of oil well completion and production technology, specifically relating to a window tool for branch wells. This invention also relates to a method for branch well completion operations. Background Technology

[0002] A branch well is a well that branches off from a main wellbore (vertical, directional, or horizontal) to enter an oil (gas) reservoir. Branch well technology is well applicable to fault-block layered reservoirs, multi-layered oil and gas reservoirs, depleted oil and gas reservoirs, tight oil and gas reservoirs, and shale gas, and is an effective technical means to achieve efficient development of low-grade oil and gas reservoirs.

[0003] Internationally, branch well completion technology is classified into six levels. Level 3 and above branch wells require sidetracking within the casing, using specialized branch well window tools for mechanical support of the branch well window, and subsequent re-entry into the main branch wellbore. Traditional branch well window tools suffer from problems such as complex structure, cumbersome operation, poor positioning and orientation accuracy, low reliability, weak mechanical support of the window, low anchoring bearing capacity, and inability to effectively seal the top annulus. Summary of the Invention

[0004] To address the technical problems described above, this invention aims to provide a window tool and a method for completing branch wells. This window tool and method for completing branch wells are simple, reliable, quick to construct, and precise in directional adjustment. It eliminates the need for directional adjustment operations at the wellhead, significantly simplifying the branch well completion process and greatly improving the success rate of branch well completion operations.

[0005] Therefore, according to a first aspect of the present invention, a window tool for a branch well is provided, comprising: a main wellbore connector for connecting to a main wellbore, comprising a first connector body and a positioning plug fixedly connected to the lower end of the first connector body, the first connector body having a first pre-opened window; and a branch wellbore connector for connecting to a branch wellbore, comprising a second connector body having a second pre-opened window; wherein the main wellbore connector is adaptable to and automatically rotates and adjusts to an anchor packer located below the branch well window via the positioning plug, so that the first pre-opened window is aligned with the branch wellbore; the branch wellbore connector is capable of entering the main wellbore connector and entering the branch wellbore through the first pre-opened window; and the branch wellbore connector is configured to adapt to the main wellbore connector and automatically adjust to make the second pre-opened window coincide with the first pre-opened window, thereby enabling the main wellbore or branch wellbore reconnection operation to be performed as needed via the main wellbore connector or the branch wellbore connector, for fracturing operation of the main wellbore or branch wellbore.

[0006] In one embodiment, the main wellbore connector further includes a guide cylinder fixed within the first connector body, the guide cylinder being located at the lower end of the first pre-opening window, and the upper end face of the guide cylinder being configured as a first guide slope facing the first pre-opening window.

[0007] In one embodiment, the first guide bevel is formed with a wear-resistant layer by surface nitriding treatment.

[0008] In one embodiment, the positioning plug includes a plug body, and a spiral guide key, a first elastic locking boss, and a sealing assembly arranged sequentially from top to bottom on the outer periphery of the plug body. The spiral guide key is used to cooperate with the spiral guide groove on the anchor packer for automatic rotational adjustment. The first elastic locking boss is used to adapt and lock with the anchor packer. The sealing assembly is used to seal with the return sleeve of the anchor packer.

[0009] In one embodiment, the branch wellbore connector further includes a setting and sealing assembly, which anchors the branch wellbore connector and seals the annulus between the branch wellbore connector and the main well casing.

[0010] In one embodiment, the setting and sealing assembly is located at the upper part of the second connector body and includes a slip, a rubber sleeve, and a setting cone sequentially fitted onto the second connector body from top to bottom. The outer wall of the second connector body has a step with the end face facing downward. The slip sits on the step, and the setting cone is fixedly connected to the second connector body by a shear pin. The setting cone can shear the shear pin under pressure and compress the rubber sleeve and the slip, thereby causing the rubber sleeve to expand and set, and causing the slip to expand and sit.

[0011] In one embodiment, the lower end of the setting cone is configured as a first spiral guide key, and the upper end of the first connector body is provided with a first spiral guide groove. The branch well connector can automatically adjust its orientation by adapting the first spiral guide key to the first spiral guide groove.

[0012] In one embodiment, the setting cone is provided with an anti-rotation key, and the first connector body is provided with a keyway. The anti-rotation key is adapted to be installed in the keyway to prevent the setting cone from rotating.

[0013] In one embodiment, the upper end of the first connector body is provided with a clamp, the inner wall of the clamp is provided with a locking groove, and the outer wall of the second connector body is provided with a second elastic locking boss. The branch well connector can be locked by adapting the second elastic locking boss to the locking groove.

[0014] In one embodiment, a main wellbore guide is also included, comprising: The first guide body has a third pre-opened window, the lower end of which is formed as a second guide slope; The second spiral guide key formed on the outer wall of the upper end of the first guide body, and A guide head is fixedly connected to the lower end of the first guide body; The second connector body has a second spiral guide groove at its upper end. The main wellbore guide can be lowered into the main wellbore connector by a feeding tool. The guide head can enter the branch wellbore under the action of the guide tube. The second spiral guide key can be adapted to the second spiral guide groove for automatic rotation and orientation adjustment so that the third pre-opening window coincides with the second pre-opening window, so that the main wellbore is connected. Thus, the second guide inclined surface ensures that the subsequently lowered tubing can only enter the main wellbore.

[0015] In one embodiment, the outer wall of the first guide body is provided with a main wellbore guide elastic locking boss, and the inner wall of the second connector body is provided with a locking groove, wherein the main wellbore guide elastic locking boss can be adapted to the locking groove to form a lock.

[0016] In one embodiment, a branch wellbore guide is also included, comprising: The second guide body is constructed in a cylindrical shape; A sealing mechanism axially spaced apart from each other and disposed on the outer wall of the second guide body; and A third spiral guide key is formed on the outer wall of the upper end of the second guide body; The branch wellbore guide can be lowered into the main wellbore connector by a delivery tool. The end of the branch wellbore guide can enter the branch wellbore under the action of the guide tube, and the sealing mechanism is respectively positioned at both ends of the second pre-opened window to block the second pre-opened window, so that the subsequent working tubing can only enter the branch wellbore through the branch wellbore guide.

[0017] In one embodiment, the outer wall of the second guide body is provided with a third elastic locking boss, which can be adapted to the locking groove to form a lock.

[0018] According to a second aspect of the present invention, a method for completing a branch well is provided, comprising the following steps: Provides the window tools for branch wells as described above; Drill the main wellbore, run the main wellbore completion string through the tailpipe hanger, and cement the well. The anchor packer is lowered to the lower part of the pre-opened window position in the main wellbore; Drill branch wells; The main wellbore connector is lowered using a delivery tool and adapted to the anchor packer to form a lock and directional adjustment, so that the first pre-opened window connects to the branch wellbore. The branch well completion string and the branch well connector are lowered using a delivery tool. The branch well completion string enters the branch well under the guidance of the main well connector. The branch well connector is adapted to the main well connector to form a lock and directional adjustment. Cementing is performed, and anchoring and sealing are achieved through a setting and packing assembly. Based on the actual working conditions, the main and branch wellbore reconnection operations are carried out in sequence to conduct segmented fracturing operations on the branch wells.

[0019] Compared with the prior art, the advantages of this application are: According to the present invention, the window tool and completion method for branch wells can complete the positioning, orientation, anchoring, and top packing of the branch well completion string in one operation via the branch wellbore connector, eliminating the need to run in a large-diameter tailpipe hanger and top packer again. Furthermore, after the branch wellbore connector is anchored, the slips can withstand higher loads, effectively reducing the load on the main wellbore connector and its lower anchoring packer, resulting in more robust mechanical support for the branch wellbore window. After the rubber sleeve at the top of the branch wellbore connector is set, annular packing at the top of the window can be achieved, meeting the sealing requirements for the top of the window in subsequent staged fracturing operations of the branch well, eliminating the need for a dedicated top sealing device and simplifying the operation process. The window tool and completion method of the present invention can meet the completion requirements of level 3 and 4 branch wells, and can also provide a window foundation for level 5 branch wells. The window tool and branch well completion method of the present invention can achieve effective mechanical support for the branch well window, enabling both the main and branch wellbores to achieve large diameters. It allows for re-entry of the main and branch wellbores separately in the later stage. The operation is simple, reliable and fast, and the positioning and orientation are accurate and reliable. There is no need for wellhead adjustment operations, which further simplifies the branch well completion operation procedure and improves the success rate of branch well completion operations. Attached Figure Description

[0020] The present invention will now be described with reference to the accompanying drawings.

[0021] Figure 1 The structure of a window tool (excluding the main wellbore guide and the branch wellbore guide) for branch wells according to the present invention is schematically shown.

[0022] Figure 2 yes Figure 1 The image shows a cross-sectional view of the window tool used for branch wells.

[0023] Figure 3 schematically shown Figure 2The structure of the main borehole connector in the window tool for branch wells is shown.

[0024] Figure 4 schematically shown Figure 2 The diagram shows the structure of the branch wellbore connector in the window tool for branch wells.

[0025] Figure 5 The structure of the main wellbore guide is shown schematically.

[0026] Figure 6 The structure of the branch wellbore guide is shown schematically.

[0027] Figure 7 This is a schematic diagram of the completion string being lowered into the main wellbore.

[0028] Figure 8 This is a schematic diagram of the connector for the main wellbore.

[0029] Figure 9 This is a schematic diagram of the connector for the branch wellbore.

[0030] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0031] The invention will now be described with reference to the accompanying drawings.

[0032] For ease of understanding, in this application, the end closest to the wellhead is defined as the upper end, upstream end, or similar terms, for example... Figure 1 The left end is defined as the end furthest from the wellhead, while the end furthest from the wellhead is defined as the lower end, downstream end, or similar terms, for example... Figure 1 The right end of the middle. Meanwhile, the direction along the length of the window tool used for branch wells is referred to as the longitudinal direction, axial direction, or similar terminology, while the direction perpendicular to it is referred to as the transverse direction, radial direction, or similar terminology.

[0033] Figure 1 The diagram schematically illustrates the structure of a window tool (excluding the main wellbore guide and the branch wellbore guide) for branch wells according to the present invention. Figure 1 As shown, the main wellbore connector 1 and the branch wellbore connector 2. The main wellbore connector 1 is used to connect the main wellbore 29 (see...). Figure 9 ),like Figure 3 As shown, the main wellbore connector 1 includes a first connector body and a positioning plug 3 fixedly connected to the lower end of the first connector body. The first connector body is provided with a first pre-opened window 5. The branch wellbore connector 2 is used to connect to the branch wellbore 34 (see...). Figure 9 ),like Figure 4As shown, the branch wellbore connector 2 includes a second connector body, which has a second pre-opened window 19. The main wellbore connector 1 can be adapted and connected to the anchor packer 32 located below the branch well window via the positioning plug 3 and automatically rotated to adjust its orientation, so that the first pre-opened window 5 is aligned with the branch wellbore 34. The branch wellbore connector 2 can enter the main wellbore connector 1 and enter the branch wellbore 34 through the first pre-opened window 5. The branch wellbore connector 2 is configured to be adapted to the main wellbore connector 1 and automatically adjust its orientation, so that the second pre-opened window 19 coincides with the first pre-opened window 5, thereby allowing the main wellbore 28 to be connected. Thus, when branch well fracturing operations are required, the main wellbore and branch wellbore can be reconnected sequentially, and the reconnection pipe string can be reconnected to the branch well window tool, thereby allowing fracturing operations to be performed on the main wellbore and branch wellbore sequentially as needed.

[0034] like Figure 2 and Figure 3 As shown, the main wellbore connector 1 also includes a guide cylinder 6 fixed inside the first connector body. Preferably, the guide cylinder 6 is located at the lower end of the first pre-opening window 5, and the upper end face of the guide cylinder 6 is configured as a first guide slope facing the first pre-opening window 5. In one embodiment, after the guide cylinder 6 is installed inside the main wellbore connector 1, the contact point between the guide cylinder 6 and the inner wall of the first connector body is fixed by welding, and the weld is ground smooth to prevent the guide cylinder 6 from rotating downhole.

[0035] In one embodiment, the first guide bevel is formed with a wear-resistant layer (not shown) through surface nitriding treatment. For example, the first guide bevel of the guide cylinder 6 is subjected to surface hardening treatment such as nitriding, which can significantly improve the wear resistance of its surface.

[0036] According to the present invention, such as Figure 3 As shown, the positioning plug 3 includes a plug body, and, from top to bottom, a spiral guide key 8, a first resilient locking boss 9, and a sealing assembly 10 arranged on the outer periphery of the plug body. The positioning plug 3 can be inserted into the return sleeve 33 on the anchor packer 32 at the lower part of the branch well window. The spiral guide key 8 is used to cooperate with the spiral guide groove (not shown) on the anchor packer 32 for automatic rotational adjustment so that the first pre-opened window 5 of the main wellbore connector 1 is aligned with the branch wellbore 34, thereby ensuring unobstructed passage between the main wellbore 28 and the branch wellbore 34. The first resilient locking boss 9 is used to adapt to the anchor packer 32 for locking. The sealing assembly 10 is used to form a seal with the return sleeve 33 of the anchor packer 32.

[0037] like Figure 3As shown, the upper part of the first connector body is provided with a clamp 7, which is located above the first pre-opened window 5. The inner wall of the clamp 7 is provided with a locking groove 4. The locking groove 4 is used to engage with the second elastic locking boss 18 (see...) provided on the outer wall of the branch well connector 2. Figure 4 The adapter is adapted so that the branch wellbore connector 2 can lock with the main wellbore connector 1. Preferably, the clamp 7 is cylindrical in shape and has a large inner diameter to facilitate the passage of the branch wellbore connector 2.

[0038] In addition, a first spiral guide groove 11 is provided on the upper outer wall region of the first connector body. The function of the first spiral guide groove 11 will be described below.

[0039] According to the present invention, such as Figure 4 As shown, the branch wellbore connector 2 also includes a setting and sealing assembly. The branch wellbore connector 2 can be anchored by the setting and sealing assembly and the annulus between the branch wellbore connector 2 and the main wellbore casing is sealed. The setting and sealing assembly is located at the upper part of the second connector body 2 and includes a slip 13, a rubber sleeve 14, and a setting cone 16, which are sequentially fitted onto the second connector body from top to bottom. The outer wall of the second connector body has a step with the end face facing downward. The slip 13 sits on the step, thereby forming an axial limit. The setting cone 16 is fixedly connected to the second connector body by a shear pin 15. Preferably, the upper end of the setting cone 16 is constructed as a conical surface. By loading with a top-feeding tool, the setting cone 16 can shear the shear pin 15 under pressure (loading) and compress the rubber sleeve 14 and the slip 13 upward, thereby causing the rubber sleeve 14 to expand and set, sealing the annulus between the branch wellbore connector 2 and the main wellbore casing, which can meet the sealing requirements of the annulus at the top of the window during branch well fracturing operations. Simultaneously, the slip 13 expands and sets under the pressure of the setting cone 16, anchoring itself to the main wellbore 28 casing wall. Thus, the setting and packer assembly enables the branch wellbore completion string 35 to be lowered, oriented, anchored, and top-packed in a single operation. Furthermore, after anchoring, the branch wellbore connector 2 can withstand higher loads, reducing the load on the main wellbore connector 1 and its lower anchor packer 32, resulting in more robust mechanical support for the branch wellbore window.

[0040] The lower part of the second connector body of the branch wellbore connector 2 is threaded to connect to the branch wellbore completion string 35. During the completion of the branch wellbore 34, the branch wellbore connector 2 can be run in together with the branch wellbore completion string 35. Since the inner diameter of the clamp 7 of the main wellbore connector 1 is large, the branch wellbore completion string 35 and the branch wellbore connector 2 can smoothly enter the interior of the main wellbore connector 1. Since the inner diameter of the guide tube 6 at the lower part of the first pre-opening window 5 of the main wellbore connector 1 is smaller than the outer diameter of the branch wellbore completion string 35, the branch wellbore completion string 35 will enter the branch wellbore 34 under the guidance of the first guide slope of the guide tube 6.

[0041] According to one embodiment of the present invention, the lower end of the setting cone 16 is configured as a first spiral guide key, and the upper end of the first connector body is provided with a first spiral guide groove 11. When the branch wellbore connector 2 is lowered into contact with the main wellbore connector 1, the branch wellbore connector 2 can be adapted to the first spiral guide groove 11 through the first spiral guide key to achieve automatic orientation and fixation, so that the second pre-opened window 19 of the branch wellbore connector 2 is aligned with the main wellbore 29, so that the main wellbore 28 is penetrated.

[0042] In one embodiment, the setting cone 16 is provided with an anti-rotation key 17. For example, the first connector body is provided with a keyway (not shown), and the anti-rotation key 17 is adapted to be installed in the keyway 17, thereby preventing the setting cone 16 from rotating.

[0043] like Figure 4 As shown, a second elastic locking boss 18 is provided on the outer wall of the second connector body. Preferably, the second elastic locking boss 18 is disposed between the second pre-opening window 19 and the setting cone 16 in the axial direction. The branch well connector 2 can be locked by fitting the second elastic locking boss 18 with the locking groove 4 on the first connector body.

[0044] In addition, such as Figure 4 As shown, a second spiral guide groove 20 is provided at the upper end of the second connector body. Furthermore, a locking groove 12 is provided on the inner wall of the second connector body. Preferably, the locking groove 12 is located between the second spiral guide groove 20 and the axial direction of the sealing assembly. The functions of the second spiral guide groove 20 and the locking groove 12 will be described below.

[0045] The window tool for branch wells according to the present invention also includes a main wellbore guide 36, such as Figure 5As shown, the main wellbore guide 36 includes a first guide body, a second spiral guide key 27 formed on the upper outer wall of the first guide body, and a guide head 24 fixedly connected to the lower end of the first guide body. The first guide body has a third pre-opening window 25, the lower end of which forms a second guide slope. The outer diameter of the main wellbore guide 36 is smaller than the inner diameter of the main wellbore connector 1. The main wellbore guide 36 can be lowered into the wellbore by a feeding tool and enter the main wellbore connector 1. The guide head 24 can enter the branch wellbore 34 under the action of the guide tube 6 of the main wellbore connector 1. The second spiral guide key 27 can be adapted to the second spiral guide groove 20 of the branch wellbore connector 2 to achieve automatic rotation and orientation, so that the third pre-opening window 25 coincides with the second pre-opening window 19 and is aligned with the main wellbore 29, allowing the main wellbore 29 to be connected. Thus, the second guide slope at the lower end of the third pre-opening window 25 ensures that the subsequently lowered tubing can only enter the main wellbore 29.

[0046] like Figure 5 As shown, the outer wall of the first guide body is provided with a main wellbore guide elastic locking boss 26, and the inner wall of the second connector body is provided with a locking groove 12. The main wellbore guide elastic locking boss 26 can be adapted to the locking groove 12 to form a lock, thereby locking the main wellbore guide 36 with the branch wellbore connector 2.

[0047] The window tool for branch wells according to the present invention also includes a branch wellbore guide 37, such as Figure 6 As shown, the branch wellbore guide 37 includes a cylindrical second guide body, two axially spaced sealing mechanisms 21 disposed on the outer wall of the second guide body, and a third spiral guide key 23 formed on the upper outer wall of the second guide body. When re-entering the branch wellbore 34 is required, the branch wellbore guide 37 can be lowered into the main wellbore connector 1 using a drive tool. The end of the branch wellbore guide 37 can enter the branch wellbore connector 2 under the guidance of the guide tube 6 of the main wellbore connector 1, and the two sealing mechanisms 21 are respectively positioned at the axial ends of the second pre-opened window 19 to effectively block and seal the second pre-opened window 19 of the branch wellbore connector 2. Thus, subsequent working tubing can only enter the branch wellbore 34 through the branch wellbore guide 37.

[0048] like Figure 6 As shown, the outer wall of the second guide body is provided with a third elastic locking boss 22. The third elastic locking boss 22 can be adapted to the locking groove 12 on the inner wall of the second connector body to form a lock, thereby locking the branch wellbore guide 37 and the branch wellbore connector 2.

[0049] If it is necessary to retrieve the main wellbore guide 36 and the branch wellbore guide 37 later, a retrieval tool can be lowered. The retrieval tool can be locked with the main wellbore guide 36 and the branch wellbore guide 37. After lifting a certain load, the elastic locking boss of the main wellbore guide 36 and the branch wellbore guide 37 can be disengaged from the locking groove 12 of the branch wellbore connector 2 and then retrieved from the wellhead.

[0050] This invention also provides a method for completing a branch well, which uses the aforementioned window tool for branch wells. The following section uses a fourth-stage completion of a branch well as an example to detail the workflow of the window tool for branch wells and the method for completing the branch well.

[0051] First, drill the main wellbore 29. After drilling the main wellbore 29, use the tailpipe hanger 31 to run the main wellbore completion string 30 and cement it as needed. Then, run a large-diameter anchor packer 32 below the pre-opened window position of the main wellbore 28. The anchor packer 32 is equipped with a return sleeve 33 and a spiral guide mechanism on its upper part.

[0052] Next, a retrievable directional drilling tool is lowered into the return sleeve 33 of the anchor packer 32 to form a lock and adjust the direction. A side-drilling tool is lowered to perform window side-drilling, drilling a branch wellbore 34. After the branch wellbore 34 is drilled, a fishing tool is lowered to retrieve and extract the retrievable directional drilling tool.

[0053] Next, the main wellbore connector 1 is lowered using a delivery tool. The positioning plug 3 of the main wellbore connector 1 is inserted into the return sleeve 33 of the anchor packer 32 to form a lock and adjust the direction. The pre-opened window 5 of the main wellbore connector 1 connects to the branch wellbore 34. Then, the delivery tool of the main wellbore connector 1 is released and removed.

[0054] Subsequently, the branch well completion string 35 and the branch well connector 2 are lowered using the delivery tool. The branch well completion string 35 enters the branch well 34 under the guidance of the main well connector 1. After the branch well connector 2 is in place, it locks and adjusts with the main well connector 1 to carry out cementing operations. After the cementing operations are completed, the shear pins 15 on the setting cone 16 are cut by loading the top delivery tool. The branch well connector 2 completes the setting and sealing, realizing the anchoring and isolation of the top of the branch well window.

[0055] When it is necessary to carry out segmented fracturing operations on branch wells, the main and branch wellbores can be reconnected in sequence. The reconnection tubing is reconnected to the branch well window tool. The rubber sleeve 14 at the top of the branch wellbore connector 2 can meet the annulus isolation requirements during fracturing operations, and the slip 13 at the top of the branch wellbore connector 2 can meet the high load-bearing requirements during fracturing operations. Fracturing operations can be carried out on the main and branch wellbores in sequence as needed.

[0056] If a specific wellbore needs to be addressed later, selective re-entry tools must be run. For example, a main wellbore guide 36 and a branch wellbore guide 37 can be run as needed for main and branch wellbore re-entry operations. When re-entering the main wellbore, the main wellbore guide is run. The end of the main wellbore guide is a solid, arc-shaped guide head with a pre-opened window in the middle and an elastic locking boss and a helical guide key at the top. After the main wellbore guide enters the main wellbore connector, the guide tube of the main wellbore connector guides the guide head of the main wellbore guide into the branch wellbore. The helical guide key at the top of the main wellbore guide automatically adjusts its orientation under the guidance of the helical guide groove at the top of the branch wellbore connector, so that the pre-opened window of the main wellbore guide coincides with the pre-opened window of the branch wellbore connector, aligning with the main wellbore and enabling the main wellbore to be connected. The guide ramp at the lower end of the pre-opened window of the main wellbore guide ensures that the subsequently run tubing can only enter the main wellbore. When re-entry into the branch wellbore is required, a branch wellbore guide can be run. The branch wellbore guide is a cylindrical design with sealing mechanisms on both sides to effectively seal the pre-opened window of the branch wellbore connector. Its upper part has an elastic locking mechanism that locks with the branch wellbore connector after insertion, ensuring that subsequent work tubing can only enter the branch wellbore. Both the main wellbore guide and the branch wellbore guide can be retrieved from the wellhead later using fishing tools. Similarly, the main wellbore guide 36 and the branch wellbore guide 37 can be run later as needed for main and branch wellbore re-entry operations.

[0057] According to the present invention, the window tool and branch well completion method for branch wells can complete the positioning, orientation, anchoring, and top packing of the branch well completion string in one operation through the branch well connector 2, without the need to run in a large-diameter tailpipe hanger and top packer again. Furthermore, after the branch well connector 2 is anchored, the slips 13 can withstand higher loads, effectively reducing the load on the main well connector 1 and its lower anchoring packer 32, making the mechanical support of the branch well window more robust. After the rubber sleeve 14 at the top of the branch well connector 2 is set, it can achieve annular packing at the top of the window, meeting the packing requirements of the top of the window in subsequent branch well fracturing operations, eliminating the need for a dedicated top sealing device and simplifying the operation process. The window tool and branch well completion method of the present invention can meet the completion requirements of level 3 and 4 branch wells, and can also provide a window foundation for level 5 branch wells. The window tool and branch well completion method of the present invention can achieve effective mechanical support for the branch well window, enabling both the main and branch wellbores to achieve large diameters. It allows for re-entry of the main and branch wellbores separately in the later stage. The operation is simple, reliable and fast, and the positioning and orientation are accurate and reliable. There is no need for wellhead adjustment operations, which further simplifies the branch well completion operation procedure and improves the success rate of branch well completion operations.

[0058] In the description of this invention, 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 invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0059] Furthermore, 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. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention 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 the present invention should be included within the protection scope of the present invention.

Claims

1. A window tool for branch wells, comprising: The main wellbore connector (1) for connecting the main wellbore (29) includes a first connector body, a positioning plug (3) fixedly connected to the lower end of the first connector body, and a guide cylinder (6) fixed inside the first connector body. The first connector body is provided with a first pre-opening window (5), the guide cylinder is located at the lower end of the first pre-opening window, and the upper end face of the guide cylinder is configured as a first guide slope facing the first pre-opening window. A branch well connector (2) for connecting a branch wellbore (34) includes a second connector body having a second pre-opened window (19) and a second spiral guide groove (20) at the upper end of the second connector body; and The main wellbore guide (36) includes a first guide body, a second spiral guide key (27) formed on the outer wall of the upper end of the first guide body, and a guide head (24) fixedly connected to the lower end of the first guide body. The first guide body is provided with a third pre-opening window (25), and the lower end of the third pre-opening window is formed as a second guide slope. The main wellbore connector can be adapted and automatically rotated to engage with the anchor packer (32) located below the branch well window via the positioning plug, so that the first pre-opened window is aligned with the branch wellbore. The branch wellbore connector can enter the main wellbore connector and enter the branch wellbore through the first pre-opened window. The branch wellbore connector is configured to be adapted to the main wellbore connector and automatically rotated to make the second pre-opened window coincide with the first pre-opened window, thereby enabling the main wellbore to be connected. As needed, the main wellbore or branch wellbore can be reconnected via the main wellbore connector or the branch wellbore connector to perform fracturing operations on the main wellbore or branch wellbore. The main wellbore guide can be lowered into the main wellbore connector by a feeding tool. The guide head can enter the branch wellbore under the action of the guide tube. The second spiral guide key can be adapted to the second spiral guide groove for automatic rotation and orientation adjustment so that the third pre-opening window coincides with the second pre-opening window, so that the main wellbore is connected. Thus, the second guide inclined surface ensures that the subsequently lowered tubing can only enter the main wellbore.

2. The window tool for branch wells according to claim 1, characterized in that, The first guide slope has a wear-resistant layer formed by surface nitriding treatment.

3. The window tool for branch wells according to claim 1 or 2, characterized in that, The positioning plug includes a plug body, and a spiral guide key (8), a first elastic locking boss (9), and a sealing component (10) arranged sequentially from top to bottom on the outer periphery of the plug body. The spiral guide key is used to cooperate with the spiral guide groove on the anchor packer for automatic rotation and orientation adjustment; the first elastic locking boss is used to fit and lock with the anchor packer; and the sealing assembly is used to seal with the return sleeve of the anchor packer.

4. The window tool for branch wells according to claim 1, characterized in that, The branch wellbore connector also includes a setting and sealing assembly, which anchors the branch wellbore connector and seals the annulus between the branch wellbore connector and the main well casing.

5. The window tool for branch wells according to claim 4, characterized in that, The setting and sealing assembly is located at the upper part of the second connector body, and includes a collet (13), a rubber sleeve (14), and a setting cone (16) sequentially fitted onto the second connector body from top to bottom. The outer wall of the second connector body has a step with the end face facing downward. The collet sits on the step, and the setting cone is fixedly connected to the second connector body by a shear pin (15). The setting cone can shear the shear pins under pressure and compress the rubber cylinder and the slips upwards, thereby causing the rubber cylinder to expand and set, and causing the slips to expand and hang.

6. The window tool for branch wells according to claim 5, characterized in that, The lower end of the setting cone is configured as a first spiral guide key, and the upper end of the first connector body is provided with a first spiral guide groove (11). The branch well connector can be automatically oriented by adapting to the first spiral guide groove via the first spiral guide key.

7. The window tool for branch wells according to claim 6, characterized in that, The setting cone is provided with an anti-rotation key (17), and the first connector body is provided with a keyway. The anti-rotation key is adapted to be installed in the keyway to prevent the setting cone from rotating.

8. The window tool for branch wells according to claim 5, characterized in that, The upper end of the first connector body is provided with a clamp (7), the inner wall of the clamp is provided with a locking groove (4), and the outer wall of the second connector body is provided with a second elastic locking boss (18). The branch well connector can be locked by adapting the second elastic locking boss to the locking groove.

9. The window tool for branch wells according to claim 1, characterized in that, The outer wall of the first guide body is provided with a main wellbore guide elastic locking boss (26), and the inner wall of the second connector body is provided with a locking groove (12). The main wellbore guide elastic locking boss can be adapted to the locking groove to form a lock.

10. The window tool for branch wells according to claim 9, characterized in that, It also includes a branch wellbore guide (37), which comprises: The second guide body is constructed in a cylindrical shape; A sealing mechanism (21) is axially spaced apart from each other and disposed on the outer wall of the second guide body; and A third spiral guide key (23) is formed on the outer wall of the upper end of the second guide body. The branch wellbore guide can be lowered into the main wellbore connector by a delivery tool. The end of the branch wellbore guide can enter the branch wellbore under the action of the guide tube, and the sealing mechanism is respectively positioned at both ends of the second pre-opened window to block the second pre-opened window, so that the subsequent working tubing can only enter the branch wellbore through the branch wellbore guide.

11. The window tool for branch wells according to claim 10, characterized in that, The outer wall of the second guide body is provided with a third elastic locking boss (22), which can be adapted to the locking groove to form a lock.

12. A method for completing a branch well, comprising the following steps: Provide a window tool for branch wells according to any one of claims 1 to 11; Drill the main wellbore (29), and run the main wellbore completion string (30) through the tailpipe hanger (31) and cement the well; The anchor packer (32) is lowered to the lower part of the pre-opened window position in the main shaft; Drill branch wells (34); The main wellbore connector (1) is lowered using a delivery tool and adapted to the anchor packer to form a lock and adjust the direction so that the first pre-opened window connects to the branch wellbore. The branch well completion string (35) and the branch well connector (2) are lowered using the delivery tool. The branch well completion string enters the branch well under the guidance of the main well connector. The branch well connector is adapted to the main well connector to form a lock and directional adjustment, cementing, and anchoring and sealing by the setting and sealing assembly. Based on the actual working conditions, the main and branch wellbore reconnection operations are carried out in sequence to conduct segmented fracturing operations on the branch wells.

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