CN117365384A - Window tool for branch well and well completion operation method of branch well - Google Patents

Abstract

The invention provides a window tool for a branch well, comprising: the main well connector comprises a first connector body and a positioning plug, wherein the first connector body is provided with a first pre-opening window; a branch wellbore connector comprising a second connector body provided with a second pre-opened window; the main well connector can be matched and butted with an anchoring packer at the lower part of the branch well window through a positioning plug and automatically rotate and adjust the direction, so that the first pre-opened window is aligned with the branch well hole, the branch well connector can enter the branch well hole through the first pre-opened window, and the branch well connector is configured to be matched with the main well connector and automatically adjust the direction, so that the second pre-opened window is overlapped with the first pre-opened window to enable the main well barrel to penetrate, and thus the main well hole or the branch well hole can be subjected to a main well hole or a branch well hole tie-back operation through the main well hole connector or the branch well hole connector, and the main well hole or the branch well hole can be subjected to a fracturing operation. The invention also provides a well completion operation method of the branch well.

Description

Window tool for branch well and well completion operation method of branch well

Technical Field

The invention belongs to the technical field of petroleum well completion and production, and particularly relates to a window tool for a branch well. The invention also relates to a method of completion operation for a lateral well.

Background

Branch wells refer to branch wells drilled from the side of one main well (vertical, directional, horizontal) into an oil (gas) reservoir. The branch well technology has good applicability in a fault block layered oil reservoir, a multi-layer system oil and gas reservoir, a depleted oil and gas reservoir, a compact oil and gas reservoir, shale gas and the like, and is an effective technical means for realizing benefit development of low-grade oil and gas reservoirs.

Branch well completion techniques are internationally classified into 6 classes, wherein 3-and-above branch wells require sidetracking within the casing, mechanical support of the branch well window, late main branch wellbore re-entry, etc. by running a special branch well window tool. The traditional branch well window tool has the problems of complex structure, complex operation, poor positioning and orientation accuracy, low reliability, unstable mechanical support of the window, low anchoring bearing capacity, incapability of effectively sealing the top annular space and the like.

Disclosure of Invention

Aiming at the technical problems, the invention aims to provide a window tool for a branch well and a well completion operation method of the branch well, which are simple and reliable, quick in construction, accurate in direction adjustment, free from wellhead direction adjustment operation, remarkably simplified in well completion operation procedure of the branch well and greatly improved in success rate of well completion operation of the branch well.

To this end, according to a first aspect of the present invention, there is provided a window tool for a branch well, comprising: the main well connector used for communicating the main well comprises a first connector body and a positioning plug fixedly connected to the lower end of the first connector body, wherein the first connector body is provided with a first pre-opening window; a branch wellbore connector for communicating a branch wellbore, comprising a second connector body provided with a second pre-opening window; the main well connector can be matched and butted with an anchoring packer at the lower part of the branch well window through the positioning plug and automatically rotate and adjust the direction, so that the first pre-opening window is aligned with the branch well hole, the branch well hole connector can enter the main well connector and enter the branch well hole through the first pre-opening window, the branch well hole connector is configured to be matched with the main well hole connector and automatically adjust the direction, so that the second pre-opening window is overlapped with the first pre-opening window to enable the main well hole to penetrate, and main well hole or branch well hole tieback operation can be performed through the main well hole connector or the branch well hole connector according to requirements, so that fracturing operation can be performed on the main well hole or the branch well hole.

In one embodiment, the main wellbore connector further comprises a guide barrel secured within the first connector body, the guide barrel being at a lower end of the first pre-opening window, an upper end face of the guide barrel being configured to face a first guide ramp of the first pre-opening window.

In one embodiment, the first guide slope is formed with a wear layer by surface nitriding.

In one embodiment, the positioning plug comprises a plug body, a spiral guide key, a first elastic locking boss and a sealing assembly, wherein the spiral guide key, the first elastic locking boss and the sealing assembly are sequentially arranged on the periphery of the plug body from top to bottom, the spiral guide key is used for being matched with a spiral guide groove on an anchoring packer to automatically rotate and adjust the direction, the first elastic locking boss is used for being matched and locked with the anchoring packer, and the sealing assembly is used for sealing a tieback barrel of the anchoring packer.

In one embodiment, the branch wellbore connector further comprises a setting packer assembly by which the branch wellbore connector can be anchored and seal off an annulus between the branch wellbore connector and the main wellbore casing.

In one embodiment, the setting and packing assembly is disposed at an upper position of the second connector body and comprises a slip, a rubber cylinder and a setting cone which are sequentially sleeved on the second connector body from top to bottom, wherein the outer wall of the second connector body is provided with a step with the end face facing downwards, the slip is seated on the step, the setting cone is fixedly connected with the second connector body through a shear pin, and the setting cone can shear the shear pin and compress the rubber cylinder and the slip upwards under the action of pressurization, so that the rubber cylinder is expanded and sealed, and the slip is expanded and hung.

In one embodiment, the lower end of the setting cone is configured as a first helical guide key, the upper end of the first connector body is provided with a first helical guide groove, and the branch wellbore connector is capable of being adapted with the first helical guide groove by the first helical guide key to automatically steer.

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

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, the outer wall of the second connector body is provided with a second elastic locking boss,

the branch wellbore connector is capable of mating with the locking groove via the second resilient locking tab to form a lock.

In one embodiment, further comprising a main wellbore director comprising:

the first guider body is provided with a third pre-opening window, and the lower end of the third pre-opening window is formed into a second guiding inclined plane;

a second spiral guide key formed on the outer wall of the upper end of the first guide body, and

the guide head is fixedly connected to the lower end of the first guide body;

wherein, a second spiral guide groove is arranged at the upper end of the second connector body;

the main well guider can be placed into the main well connector through a sending tool, the guide head can enter the branch well hole under the action of the guide cylinder, the second spiral guide key can be matched with the second spiral guide groove to automatically rotate and adjust the direction, so that the third pre-opened window coincides with the second pre-opened window, the main well is communicated, and accordingly a pipe column which is placed into the main well can only enter the main well hole through the second guide inclined plane.

In one embodiment, the outer wall of the first guide body is provided with a second elastic locking boss, and the inner wall of the second connector body is provided with a locking groove, and the second elastic locking boss can be matched with the locking groove to form locking.

In one embodiment, further comprising a branch wellbore director comprising:

a second guide body configured in a cylindrical shape;

sealing means disposed on the outer wall of the second guide body axially spaced from each other; and

a third spiral guide key formed on the outer wall of the upper end of the second guide body;

the branch well hole guide device can be lowered into the main well hole connector through a running tool, the tail end of the branch well hole guide device can enter the branch well hole under the action of the guide cylinder, and the sealing mechanisms are respectively positioned at the two axial ends of the second pre-opening window to seal the second pre-opening window, so that a subsequent operation pipe column can only enter the branch well hole through the branch well hole guide device.

In one embodiment, the outer wall of the second guide body is provided with a third resilient locking boss which is adapted to form a lock with the locking groove.

According to a second aspect of the present invention there is provided a method of completion of a lateral well comprising the steps of:

providing a window tool for a branch well as described above;

drilling a main wellbore, and setting a well completion string of the main wellbore through a tail pipe hanger to fix the well;

an anchoring packer is put down to the lower part of the pre-windowing position of the main well barrel;

drilling branch wellbores;

running the main wellbore connector with a running tool and adapting the main wellbore connector to the anchoring packer to form a lock and steer, allowing the first pre-opened window to communicate with a lateral wellbore;

running a branch wellbore completion string and the branch wellbore connector by using a running tool, wherein the branch wellbore completion string enters a branch wellbore under the guidance of the main wellbore connector, and the branch wellbore connector is matched with the main wellbore connector so as to form locking and steering, well cementation and anchoring and packing by a setting packing assembly;

and sequentially carrying out main and branch well tieback operations according to actual working conditions so as to carry out branch well staged fracturing operations.

Compared with the prior art, the application has the advantages that:

according to the window tool for the branch well and the well completion operation method of the branch well, the positioning, the orientation, the anchoring and the window top packing of the well completion pipe column of the branch well can be completed at one time through the branch well connector, and a large-diameter tail pipe hanger and a top packer do not need to be put in again. And after the branch wellbore connectors are anchored, higher load can be borne by the slips, so that the load of the main wellbore connectors and the anchoring packer at the lower part of the main wellbore connectors is effectively reduced, and the mechanical support of the branch wellbore windows is firmer. After the packing element at the top of the branch wellbore connector is set, the annular packing at the top of the window can be realized, the packing requirement at the top of the window for the staged fracturing operation of the later branch wellbore can be met, a special top sealing device is not needed to be put in, and the operation process is simplified. The window tool and the method for operating the completion of the branch well can meet the requirements of the completion of the branch well of 3-level and 4-level, and can provide a window foundation for the branch well of 5-level. The window tool and the lateral well completion operation method can realize effective mechanical support of the lateral well window, so that the main and the lateral well bores can realize large drift diameters, the re-entry of the main and the lateral well bores is allowed in the later period, the operation is simple, reliable and quick, the positioning and orientation are accurate and reliable, the direction adjustment operation is not needed at the wellhead, the lateral well completion operation procedure is further simplified, and the lateral well completion operation success rate is improved.

Drawings

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

Fig. 1 schematically shows the structure of a window tool for a branch well (excluding a main well guide and a branch well guide) according to the present invention.

Fig. 2 is a cross-sectional view of the window tool for a branch well shown in fig. 1.

Fig. 3 schematically illustrates the construction of a main wellbore connector in the window tool for a branch wellbore shown in fig. 2.

FIG. 4 schematically illustrates the configuration of a lateral wellbore connector in the window tool for a lateral well shown in FIG. 2.

Fig. 5 schematically shows the structure of the main wellbore guide.

FIG. 6 schematically illustrates the construction of a branch wellbore director.

FIG. 7 is a schematic of a run-in main wellbore completion string.

FIG. 8 is a schematic of a run-in main wellbore connector.

FIG. 9 is a schematic view of a run-in branch wellbore connector.

In this application, all of the figures are schematic drawings which are intended to illustrate the principles of the invention and are not to scale.

Detailed Description

The invention is described below with reference to the accompanying drawings.

For ease of understanding, in this application, the end near the wellhead is defined as the upper end, upstream end, or the like, such as the left end in FIG. 1, and the end remote from the wellhead is defined as the lower end, downstream end, or the like, such as the right end in FIG. 1. Meanwhile, a longitudinal direction along a length of a window tool for a branch well is referred to as a longitudinal direction, an axial direction, or the like, and a direction perpendicular thereto is referred to as a lateral direction, a radial direction, or the like.

Fig. 1 schematically shows the structure of a window tool for a branch well (excluding a main well guide and a branch well guide) according to the present invention. As shown in fig. 1, a main wellbore connector 1 and a branch wellbore connector 2. The main wellbore junction 1 is configured to communicate with a main wellbore 29 (see fig. 9), and as shown in fig. 3, the main wellbore junction 1 includes a first junction body provided with a first pre-opening window 5 and a positioning plug 3 fixedly connected to a lower end of the first junction body. Branch wellbore connector 2 is used to communicate branch wellbore 34 (see fig. 9), and branch wellbore connector 2 includes a second connector body provided with a second pre-opening window 19, as shown in fig. 4. The main wellbore connector 1 is capable of mating with the anchor packer 32 in the lower portion of the branch wellbore window by the locating pin 3 and automatically rotating and steering to align the first pre-opened window 5 with the branch wellbore 34, the branch wellbore connector 2 is capable of entering the main wellbore connector 1 and entering the branch wellbore 34 through the first pre-opened window 5, and the branch wellbore connector 2 is configured to mate with the main wellbore connector 1 to automatically steer to align the second pre-opened window 19 with the first pre-opened window 5 to allow the main wellbore 28 to be penetrated. Therefore, when the staged fracturing operation of the branch well is needed, the tieback operation of the main well and the branch well can be sequentially carried out, the tieback pipe column is connected to the window tool of the branch well in a tieback mode, and then the fracturing operation of the main well and the branch well is sequentially carried out according to the needs.

As shown in fig. 2 and 3, the main wellbore connector 1 further comprises a guide cylinder 6 fixed within 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 surface of the guide cylinder 6 is configured to face the first guide slope of the first pre-opening window 5. In one embodiment, after the guide cylinder 6 is installed inside the main wellbore connector 1, the contact between the guide cylinder 6 and the inner wall of the first connector body is fixed by welding, and the welding seam is polished smoothly to prevent the guide cylinder 6 from rotating downhole.

In one embodiment, the first guide slope is formed with a wear layer (not shown) by surface nitriding. For example, the first guide slope of the guide cylinder 6 is subjected to a hardening treatment such as surface nitriding, which can significantly improve the wear resistance of the surface thereof.

According to the present invention, as shown in fig. 3, the positioning plug 3 includes a plug body, and a screw guide key 8, a first elastic locking boss 9, and a sealing assembly 10, which are sequentially provided at the outer periphery of the plug body from top to bottom. The locating plug 3 can be inserted into a tieback 33 on an anchor packer 32 in the lower part of the lateral window. The helical guide key 8 is adapted to cooperate with a helical guide groove (not shown) on the anchor packer 32 to automatically rotate the steering direction so that the first pre-opened window 5 of the main wellbore connector 1 is aligned with the branch wellbore 34, thereby ensuring that a clear gap is maintained between the main wellbore 28 and the branch wellbore 34. The first resilient locking boss 9 is adapted to be locked with the anchoring packer 32. The seal assembly 10 is used to form a seal with the tieback 33 of an anchor packer 32.

As shown in fig. 3, the upper end portion of the first connector body is provided with a clip 7, the clip 7 is correspondingly positioned at the upper portion of the first pre-opening window 5, and the inner wall of the clip 7 is provided with a locking groove 4. The locking groove 4 is adapted to mate with a second resilient locking boss 18 (see fig. 4) provided on the outer wall of the branch wellbore connector 2 to enable the branch wellbore connector 2 to form a lock with the main wellbore connector 1. Preferably, collar 7 is configured in a cylindrical shape, and the inner diameter of collar 7 is of a large diameter design to facilitate passage of branch wellbore connector 2 therethrough.

In addition, a first screw guide groove 11 is provided in an upper end outer wall region of the first connector body, and a functional function of the first screw guide groove 11 will be described below.

According to the present invention, as shown in FIG. 4, branch wellbore connector 2 further comprises a setting packer assembly by which branch wellbore connector 2 can be anchored and the annulus between branch wellbore connector 2 and the main wellbore casing is plugged. The setting packing assembly is arranged at the upper position of the second connector body 2 and comprises a slip 13, a rubber cylinder 14 and a setting cone 16 which are sleeved on the second connector body from top to bottom in sequence. The outer wall of the second connector body is provided with a step with an end face facing downwards, and the slips 13 are seated on the step, thereby forming an axial limit. The setting cone 16 is fixedly connected to the second connector body by means of shear pins 15. Preferably, the upper end of the setting cone 16 is configured as a conical surface. Through top running tool loading, setting cone 16 can shear pin 15 under the effect of pressurization (loading) and go upward to compress packing element 14 and slips 13 to make packing element 14 take place the inflation setting, shutoff branch wellbore connector 2 and the annular space between the main shaft 28 sleeve pipe can satisfy the window top annular space sealing demand when branch well fracturing operation. At the same time, the slips 13 expand under the compression of the setting cone 16 to set, forming an anchor on the casing wall of the main wellbore 28. Thus, the setting packing assembly can complete the running, orientation, anchoring and top packing of the branch wellbore completion string 35 at one time, and after the branch wellbore connector 2 is anchored, higher load can be borne, and the bearing load of the main wellbore connector 1 and the lower anchoring packer 32 thereof is relieved, so that the mechanical support of the branch wellbore window is firmer.

The lower portion of the second connector body of branch wellbore connector 2 is threaded to allow connection of branch wellbore completion string 35. When the branch wellbore 34 is completed, the branch wellbore connector 2 can be lowered together with the branch wellbore completion string 35, the branch wellbore completion string 35 and the branch wellbore connector 2 can smoothly enter the inside of the main wellbore connector 1 due to the large inner diameter of the collar 7 of the main wellbore connector 1, and the branch wellbore completion string 35 can enter the branch wellbore 34 under the guidance of the first guiding inclined surface of the guiding drum 6 due to the smaller inner diameter of the guiding drum 6 at the lower part of the first pre-opened window 5 of the main wellbore connector 1 than the outer diameter of the branch wellbore completion string 35.

According to one embodiment of the invention, the lower end of the setting cone 16 is configured as a first helical guide key, while the upper end of the first connector body is provided with a first helical guide groove 11. After branch wellbore connector 2 is lowered into contact with main wellbore connector 1, branch wellbore connector 2 is able to mate with first helical guide groove 11 via the first helical guide key for automatic steering fixation such that second pre-opened window 19 of branch wellbore connector 2 is aligned with main wellbore 29 such that main wellbore 28 is penetrated.

In one embodiment, the setting cone 16 is provided with anti-rotation keys 17. For example, the first connector body is provided with a keyway (not shown) and the anti-rotation key 17 is fitted into the keyway 17 so as to prevent rotation of the setting cone 16.

As shown in fig. 4, a second elastic locking boss 18 is provided on the outer wall of the second connector body. Preferably, a second elastic locking boss 18 is provided between the second pre-opening window 19 and the axial direction of the setting cone 16. The branch wellbore connector 2 is capable of mating with a locking groove 4 on the first connector body via a second resilient locking tab 18 to form a lock.

As shown in fig. 4, a second spiral guide groove 20 is provided at the upper end of the second connector body. And, the inner wall of the second connector body is provided with a locking groove 12, preferably the locking groove 12 is located between the second helical guide groove 20 and the axial direction of the setting packing assembly. The functional roles of the second helical guide groove 20 and the locking groove 12 will be described below.

The window tool for a lateral well according to the present invention further includes a main wellbore guide 36, as shown in fig. 5, the main wellbore guide 36 including a first guide body, a second screw guide key 27 formed at an outer wall of an upper end of the first guide body, and a guide head 24 fixedly coupled to a 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 25 is formed to be a second guide inclined plane. The outer diameter of the main borehole guide 36 is smaller than the inner diameter of the main borehole connector 1, the main borehole guide 36 can be lowered into the borehole by a running tool and enter the main borehole connector 1, the guide head 24 can enter the branch borehole 34 under the action of the guide cylinder 6 of the main borehole connector 1, and the second spiral guide key 27 can be matched with the second spiral guide groove 20 of the branch borehole connector 2 to realize automatic rotation and direction adjustment, so that the third pre-opening window 25 coincides with the second pre-opening window 19 and is aligned with the main borehole 29, and the main borehole 29 is penetrated. Thus, the subsequent run in string is allowed to enter the main wellbore 29 only by the second guiding ramp at the lower end of the third pre-opening window 25.

As shown in fig. 5, the outer wall of the first guide body is provided with a second resilient locking boss 26, the inner wall of the second connector body is provided with a locking groove 12, and the second resilient locking boss 26 can be fitted with the locking groove 12 to form a lock, thereby locking the main wellbore guide 36 with the branch wellbore connector 2.

The window tool for a branch well according to the present invention further includes a branch wellbore guide 37, as shown in fig. 6, the branch wellbore guide 37 including a second guide body constructed in a cylindrical shape, 2 sealing mechanisms 21 disposed on an outer wall of the second guide body to be axially spaced apart from each other, and a third helical guide key 23 formed on an outer wall of an upper end of the second guide body. When it is desired to re-enter branch wellbore 34, branch wellbore director 37 can be lowered into main wellbore connector 1 by the running tool, the distal end of branch wellbore director 37 can be guided into branch wellbore connector 2 by guiding barrel 6 of main wellbore connector 1, and 2 sealing mechanisms 21 are respectively positioned at the axial ends of second pre-opening window 19 to effectively seal and block second pre-opening window 19 of branch wellbore connector 2. Thus, subsequent work string is allowed to enter branch wellbore 34 only through branch wellbore director 37.

As shown in fig. 6, the outer wall of the second guide body is provided with a third resilient locking boss 22, the third resilient locking boss 22 being capable of mating with the locking groove 12 of the inner wall of the second connector body to form a lock, thereby locking branch wellbore guide 37 with branch wellbore connector 2.

If the main well guide 36 and the branch well guide 37 need to be lifted in the later period, a fishing tool can be put into, the fishing tool can be locked with the main well guide 36 and the branch well guide 37, a certain load is lifted upwards, and the elastic locking bosses of the main well guide 36 and the branch well guide 37 can be pulled out from the locking grooves 12 of the branch well connector 2, so that a wellhead is lifted.

The invention also provides a well completion operation method of the branch well, which uses the window tool for the branch well. The workflow of the window tool for the branch well and the method of the branch well completion operation will be described in detail below by taking the four-stage completion of the branch well as an example.

First, main wellbore 29 is drilled, and after main wellbore 29 is drilled, main wellbore completion string 30 is run down as needed using liner hanger 31, and well is cemented. Then, an anchor packer 32 with a large diameter is placed below the pre-window position of the main well casing 28, and a tieback casing 33 and a spiral guide mechanism are provided above the anchor packer 32.

Thereafter, the removable whipstock is lowered and inserted into the tieback barrel 33 of the anchor packer 32 to lock and steer. The side drilling tool is used for opening window and side drilling, the branch well bores 34 are drilled, and after the branch well bores 34 are drilled, the fishing tool is used for fishing to provide the removable whipstock.

Thereafter, the running tool is used to run the main wellbore connector 1, the locating plug 3 of the main wellbore connector 1 is inserted into the tieback cylinder 33 of the anchoring packer 32 to form locking and steering, the pre-opened window 5 of the main wellbore connector 1 is communicated with the branch wellbore 34, and the running tool of the main wellbore connector 1 is released.

Then, a running tool is used for running the branch well completion pipe column 35 and the branch well connector 2, the branch well completion pipe column 35 enters the branch well 34 under the guidance of the main well connector 1, after the branch well connector 2 is in place, locking and direction adjustment are formed with the main well connector 1, well cementation operation is carried out, after the well cementation operation is finished, the top running tool is used for loading, shear pins 15 on the setting cone 16 are sheared, the branch well connector 2 is completely set and sealed, and anchoring and sealing of the top of the branch well window are realized.

When the staged fracturing operation of the branch well is needed, the tieback operation of the main and branch well bores can be sequentially carried out, the tieback pipe column is connected back to the window tool of the branch well, the packing element 14 at the top of the branch well bore connector 2 can meet the annular packing requirement during the fracturing operation, the slips 13 at the top of the branch well bore connector 2 can meet the high bearing requirement during the fracturing operation, and the fracturing operation can be sequentially carried out on the main and branch well bores according to the needs.

Later, if a separate treatment of a wellbore is required, an optional re-entry tool is required. For example, main wellbore guide 36 and branch wellbore guide 37 may be run in as needed to perform main and branch wellbore re-entry operations. When the main well is required to be reentered, the main well is reentered, the tail end of the main well is a guide head in an arc solid design, the middle part of the main well is a pre-opened window, the upper part of the main well is provided with an elastic locking boss and a spiral guide key, after the main well is reentered into the main well connector, the guide cylinder of the main well connector can guide the guide head of the main well to enter the branch well, the spiral guide key at the top of the main well is automatically adjusted under the guidance of the spiral guide groove at the top of the branch well connector, so that the pre-opened window of the main well is overlapped with the pre-opened window of the branch well connector, and the main well is aligned, so that the main well is penetrated. The guiding inclined plane at the lower end of the pre-opening window of the main well hole guider enables the pipe column which is subsequently lowered to only enter the main well hole. When the branch well bore is required to be reentered, the branch well bore guide can be lowered, the branch well bore guide is of a barrel type design, sealing mechanisms are arranged on two sides of the branch well bore guide, a pre-opened window of the branch well bore connector can be effectively plugged, an elastic locking mechanism is arranged on the upper portion of the branch well bore guide, the branch well bore guide can be locked with the branch well bore connector after being inserted, and a subsequent operation pipe column can only enter the branch well bore. The main well guide and the branch well guide can be fished out of the well mouth through a lower fishing tool at a later stage. Later, main wellbore guide 36 and branch wellbore guide 37 may be lowered as needed to perform main and branch wellbore re-entry operations.

According to the window tool for the branch well and the well completion operation method of the branch well, the positioning, the orientation, the anchoring and the window top packing of the well completion pipe column of the branch well can be completed at one time through the branch well connector 2, and a large-diameter tail pipe hanger and a top packer do not need to be put in again. In addition, after the branch wellbore connector 2 is anchored, higher load can be borne through the slips 13, so that the load of the main wellbore connector 1 and the lower anchoring packer 32 thereof is effectively reduced, and the mechanical support of the branch wellbore window is firmer. After the packing element 14 at the top of the branch wellbore connector 2 is set, the annular packing at the top of the window can be realized, the packing requirement at the top of the window for the staged fracturing operation of the later branch wellbore can be met, a top sealing device is not required to be specially arranged, and the operation process is simplified. The window tool and the method for operating the completion of the branch well can meet the requirements of the completion of the branch well of 3-level and 4-level, and can provide a window foundation for the branch well of 5-level. The window tool and the lateral well completion operation method can realize effective mechanical support of the lateral well window, so that the main and the lateral well bores can realize large drift diameters, the re-entry of the main and the lateral well bores is allowed in the later period, the operation is simple, reliable and quick, the positioning and orientation are accurate and reliable, the direction adjustment operation is not needed at the wellhead, the lateral well completion operation procedure is further simplified, and the lateral well completion operation success rate is improved.

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

Furthermore, in the description herein, reference to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Finally, it should be noted that the above description is only of a preferred embodiment of the invention and is not to be construed as limiting the invention in any way. Although the invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the techniques described in the foregoing examples, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (14)

1. A window tool for a branch well, comprising:

the main well connector (1) is used for communicating a main well (29) and comprises a first connector body and a positioning plug (3) fixedly connected to the lower end of the first connector body, wherein the first connector body is provided with a first pre-opening window (5);

a branch wellbore connector (2) for communicating a branch wellbore (34) comprising a second connector body provided with a second pre-opening window (19);

wherein the main wellbore connector is adapted to dock with an anchor packer (32) at a lower portion of a lateral wellbore window by the locating pin and automatically swivel to align the first pre-opened window with the lateral wellbore, the lateral wellbore connector is adapted to enter the main wellbore connector and enter the lateral wellbore through the first pre-opened window, and the lateral wellbore connector is configured to be adapted to automatically swivel with the main wellbore connector to align the second pre-opened window with the first pre-opened window to allow the main wellbore to pass through, thereby enabling a main wellbore or lateral wellbore tieback operation to be performed on the main wellbore or the lateral wellbore through the main wellbore connector or the lateral wellbore connector as required.

2. The window tool for a branch well according to claim 1, wherein the main wellbore connector further comprises a guide cylinder (6) fixed within the first connector body, the guide cylinder being at a lower end of the first pre-opening window, an upper end face of the guide cylinder being configured to face a first guide slope of the first pre-opening window.

3. The window tool for a branch well of claim 2, wherein the first guide slope is formed with a wear-resistant layer by surface nitriding treatment.

4. A window tool for a branch well according to any one of claims 1 to 3, wherein the positioning plug comprises a plug body, and a screw guide key (8), a first elastic locking boss (9), and a sealing assembly (10) sequentially provided on the outer periphery of the plug body from top to bottom,

the spiral guide key is used for being matched with a spiral guide groove on the anchoring packer to automatically rotate and adjust the direction, the first elastic locking boss is used for being matched and locked with the anchoring packer, and the sealing assembly is used for being sealed with a tieback cylinder of the anchoring packer.

5. The window tool for a branch well of claim 2, wherein the branch wellbore connector further comprises a setting packer assembly by which the branch wellbore connector can be anchored and the annulus between the branch wellbore connector and the main wellbore casing is sealed off.

6. The window tool for a branch well according to claim 5, wherein the setting packing assembly is arranged at the upper part of the second connector body and comprises a slip (13), a rubber cylinder (14) and a setting cone (16) which are sleeved on the second connector body from top to bottom in sequence, the outer wall of the second connector body is provided with a step with the end face facing downwards, the slip sits on the step, the setting cone is fixedly connected with the second connector body through a shear pin (15),

the setting cone body can shear the shear pins under the action of pressurization and compress the rubber cylinder and the slips upwards, so that the rubber cylinder is expanded and set, and the slips are expanded and set.

7. The window tool for a branch well according to claim 6, wherein the lower end of the setting cone is configured as a first screw guide key, the upper end of the first connector body is provided with a first screw guide groove (11),

the branch wellbore connector is adaptable with the first helical guide key and the first helical guide groove to automatically steer.

8. A window tool for a branch well according to claim 7, wherein the setting cone is provided with an anti-rotation key (17), the first connector body being provided with a key slot, the anti-rotation key being adapted to fit within the key slot to prevent rotation of the setting cone.

9. The window tool for a branch well according to claim 6, wherein the upper end of the first connector body is provided with a collar (7), the inner wall of the collar is provided with a locking groove (4), the outer wall of the second connector body is provided with a second elastic locking boss (18),

the branch wellbore connector is capable of mating with the locking groove via the second resilient locking tab to form a lock.

10. The window tool for a branch well of claim 2, further comprising a main wellbore director (36) comprising:

a first guide body provided with a third pre-opening window (25), the lower end of which forms a second guide inclined plane;

a second spiral guide key (27) formed on the outer wall of the upper end of the first guide body, and

the guide head (24) is fixedly connected to the lower end of the first guide body;

wherein a second spiral guide groove (20) is arranged at the upper end of the second connector body;

the main well guider can be placed into the main well connector through a sending tool, the guide head can enter the branch well hole under the action of the guide cylinder, the second spiral guide key can be matched with the second spiral guide groove to automatically rotate and adjust the direction, so that the third pre-opened window coincides with the second pre-opened window, the main well is communicated, and accordingly a pipe column which is placed into the main well can only enter the main well hole through the second guide inclined plane.

11. Window tool for a branch well according to claim 10, characterized in that the outer wall of the first guide body is provided with a second resilient locking boss (26), the inner wall of the second connector body is provided with a locking groove (12), the second resilient locking boss being adapted to form a lock with the locking groove.

12. A window tool for a branch well according to claim 11, further comprising a branch wellbore director (37) comprising:

a second guide body configured in a cylindrical shape;

sealing means (21) axially spaced apart from each other on the outer wall of the second guide body; and

a third spiral guide key (23) formed on the outer wall of the upper end of the second guide body;

the branch well hole guide device can be lowered into the main well hole connector through a running tool, the tail end of the branch well hole guide device can enter the branch well hole under the action of the guide cylinder, and the sealing mechanisms are respectively positioned at the two axial ends of the second pre-opening window to seal the second pre-opening window, so that a subsequent operation pipe column can only enter the branch well hole through the branch well hole guide device.

13. Window tool for a branch well according to claim 12, characterized in that the outer wall of the second guide body is provided with a third resilient locking boss (22) which is adapted to form a lock with the locking groove.

14. A method of branch well completion operations comprising the steps of:

providing a window tool for a branch well according to any one of claims 1 to 13;

drilling a main well hole (29), and lowering a main well hole completion pipe column (30) through a tail pipe hanger (31) to fix the well;

lowering an anchor packer (32) to a lower portion of the main wellbore pre-windowing position;

drilling a branch wellbore (34);

lowering the main wellbore connector (1) using a running tool and adapting the main wellbore connector to the anchoring packer to form a lock and steer, placing the first pre-opened window in communication with the lateral wellbore;

running a lateral wellbore completion string (35) and the lateral wellbore connector (2) using a running tool, the lateral wellbore completion string being run into the lateral wellbore under the guidance of the main wellbore connector, the lateral wellbore connector being adapted to form a lock and steering, cementing, anchoring and packing by a setting packing assembly;

and sequentially carrying out main and branch well tieback operations according to actual working conditions so as to carry out branch well staged fracturing operations.