Expansion pipe column structure for shaft reconstruction

Abstract

The invention relates to the technical field of oil and gas field development, and particularly discloses an expansion pipe column structure for shaft reconstruction, which comprises an expansion pipe, a bottom plug and an expansion cone assembly, the expansion cone assembly and the bottom plug are sequentially arranged in a prefabricated expansion cavity expanded outwards at the end part of the expansion pipe, and the expansion cone assembly and the cavity wall of the prefabricated expansion cavity are slidably sealed; the bottom plug seal is used for sealing the prefabricated expansion cavity, the interior of the expansion cone assembly is connected with one end of a plug-in connection seat through a releasing structure, the releasing structure is used for releasing the expansion cone assembly, the other end of the plug-in connection seat is connected with one end of a plug-in connector, and the plug-in connection seat and the plug-in connector are connected through a clamping ring structure. And an inserting oil pipe is detachably connected into the other end of the inserting connector. According to the expansion pipe column structure, operation is safer in the expansion process of the expansion pipe, large-pressure-difference sealing can be achieved, and the larger well completion inner diameter can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, in particular to an expansion pipe string structure used for wellbore reconstruction. Background Art

[0002] In recent years, shale oil and gas resources have been developed and utilized on a large scale. At the same time, the important production characteristics of shale oil and gas wells are large and fast production decline, which has gradually become an important constraint on their economic and efficient development. After fracturing of shale gas and tight oil and gas wells, as the oil and gas in the original fractures are continuously resolved during production and development, the fractures gradually close and the production declines rapidly. In order to ensure the economic efficiency of oil and gas development and fully release the oil and gas production capacity of the reservoir, repeated fracturing of the production layer after production declines can effectively improve the development efficiency of the oil field. In general shale oil and gas areas, through the analysis of repeated fracturing wells in the block, it was found that the initial annual oil production decline rate after repeated fracturing was about 56%, which was lower than the initial annual decline rate of 64% of new wells.

[0003] Practice has proved that hydraulic expansion is more operable than mechanical expansion, but the existing expansion methods mostly use direct pressure expansion or single-stage hydraulic cylinder expansion, which requires high pump pressure and high construction risks. Once pressure leakage occurs, expansion will not be able to continue. Compared with conventional repeated fracturing schemes such as new fracturing and diversion fracturing in the same layer, the expansion tube technology is used to seal the perforated section in the original wellbore casing of shale oil and gas wells, rebuild the wellbore integrity, and re-perforate for fracturing. This technology has high pressure-bearing capacity after sealing, can accurately control the isolation of the original perforated section, and increase the probability of creating new fractures, which can significantly increase the production and ultimate recoverable resources (EUR) of shale oil and gas wells. Summary of the invention

[0004] The object of the present invention is to provide an expandable pipe string structure for wellbore reconstruction, which is safer to operate during the expansion of the expandable pipe, can achieve large pressure difference sealing, and can obtain a larger completion inner diameter.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] An expansion pipe string structure for wellbore reconstruction comprises an expansion pipe, a bottom plug and an expansion cone assembly, wherein an expansion cone assembly and a bottom plug are sequentially arranged in a prefabricated expansion cavity expanded outward from the end of the expansion pipe, and the expansion cone assembly and the cavity wall of the prefabricated expansion cavity are slidably sealed, and the bottom plug seal is used to close the prefabricated expansion cavity, and the expansion cone assembly is connected to one end of a plug-in socket through a release structure inside the expansion cone assembly, and the release structure is used to release the expansion cone assembly, and the other end of the plug-in socket is connected to one end of a plug-in joint, and the plug-in socket and the plug-in joint are connected by a clamping ring structure, and a plug-in oil pipe is detachably connected to the other end of the plug-in joint.

[0007] In a further solution, the plug-in connector and the plug-in socket are mutually matching plug-in pipe columns, and the matching connection between the two pipe columns is a stepped cylinder. The diameter of the stepped cylinder at one end of the plug-in connector close to the plug-in socket increases successively, and the maximum diameter is smaller than the diameter of the expansion tube.

[0008] In a further solution, the mating surface of the connection between the plug-in oil pipe and the plug-in connector is a stepped cylindrical surface.

[0009] In a further embodiment, the release structure includes mutually connected reverse-rotation thread structures respectively arranged on the inner wall surface of the expansion cone assembly and the outer wall surface of the plug-in socket, and the reverse-rotation thread structures are disengaged when the plug-in socket rotates clockwise.

[0010] In a further solution, the release structure includes a shearable pin and a pin hole respectively arranged on the inner wall surface of the expansion cone assembly and the outer wall surface of the plug-in socket and interlocking with each other.

[0011] In a further solution, one end of the bottom plug is sealedly connected to the prefabricated expansion chamber via a sealing ring, and the other end is connected to the prefabricated expansion chamber via a shearable thread.

[0012] In a further solution, the clamping ring structure includes a male buckle and a female buckle respectively arranged on the plug-in socket and the plug-in connector, and the male buckle and the female buckle are locked with each other after the plug-in socket and the plug-in connector are plugged in.

[0013] In a further solution, the male buckle is a bayonet pin and the female buckle is a slot.

[0014] In a further solution, the plug-in connector and the plug-in oil pipe are connected by threads.

[0015] In a further solution, a plurality of groups of composite rubbers are connected to the outer wall of the expansion tube, and the composite rubbers are used to seal and support the expansion tube in the casing.

[0016] Beneficial effects of the present invention:

[0017] The invention provides a release structure in the expansion cone assembly. When the expansion cone assembly encounters resistance or jamming and cannot expand normally, the release structure can be reversed to remove the plug-in oil pipe, thereby improving the safety of the operation.

[0018] The present invention facilitates the straightening of the plug-in oil pipe when it enters the expansion pipe by arranging the plug-in joint, facilitates the guided insertion of the plug-in oil pipe, and facilitates the guidance and straightening of the expansion cone assembly during the expansion of the expansion pipe by arranging the plug-in socket.

[0019] After the expansion pipe of the present invention is expanded by the expansion cone assembly, multiple groups of combined rubbers are used to closely fit the casing, thereby achieving large pressure difference sealing. Adjacent sealing sections can withstand greater fracturing pressure, which is convenient for re-perforating for fracturing, and a larger completion inner diameter can be obtained, which is convenient for rebuilding the wellbore. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a schematic diagram of an expandable pipe string structure for wellbore reconstruction in an embodiment of the present invention;

[0022] Figure 2 1 is a schematic structural diagram of an expansion state of an expansion tube in a wellbore casing according to an embodiment of the present invention;

[0023] Figure 3 Schematic diagram of an outer pipe string of an expandable pipe in an embodiment of the present invention;

[0024] Figure 4 Schematic diagram of a tubular column in an expandable tube according to an embodiment of the present invention;

[0025] Figure 5 Schematic diagram of the expansion cone assembly in the released state according to the embodiment of the present invention;

[0026] In the figure: 0, casing; 1, expansion tube; 11, prefabricated expansion chamber; 2, bottom plug; 3, expansion cone assembly; 4, release structure; 5, plug-in socket; 6, plug-in joint; 7, clamping ring structure; 8, plug-in oil pipe; 9, combined rubber. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] like Figure 1As shown, an expandable pipe string structure for wellbore reconstruction includes an expansion pipe 1, a bottom plug 2 and an expansion cone assembly 3. The expansion cone assembly 3 and the bottom plug 2 are sequentially arranged in a prefabricated expansion cavity 11 expanded outward from the end of the expansion pipe 1, and the expansion cone assembly 3 and the cavity wall of the prefabricated expansion cavity 11 are slidably sealed. The bottom plug 2 is sealed for closing the prefabricated expansion cavity 11. One end of a plug-in socket 5 is connected to the inside of the expansion cone assembly 3 through a release structure 4, and the other end of the plug-in socket 5 is connected to one end of a plug-in joint 6. The plug-in socket 5 and the plug-in joint 6 are connected by a clamping ring structure 7, and a plug-in oil pipe 8 is detachably connected to the other end of the plug-in joint 6.

[0029] Its working principle is as follows, see Figure 2 As shown, the expansion cone assembly 3 is slidably connected in the prefabricated expansion cavity 11 of the expansion tube 1, the expansion cone assembly 3 is connected to the plug-in socket 5, and then connected to the sealing connection bottom plug 2 to form the outer pipe string of the expansion tube 1, and the plug-in oil pipe 8 is connected to the plug-in joint to form the inner pipe string of the expansion tube 1, and the drill pipe is sent to lower them together to the predetermined position in the wellbore casing 0, and then the pressure expansion operation is carried out. The liquid used for pressure is introduced into the position of the bottom plug 2 under the action of the plug-in oil pipe 8, and the expansion cone assembly 3 is pushed in the reverse direction to expand the expansion tube 1, so that the expansion tube 1 is expanded and closely fits on the inner wall of the casing 0 to achieve reliable sealing, see Figure 5 As shown, when the expansion tube 1 encounters resistance during the expansion process and cannot expand normally, the inner pipe column is lowered to the bottom, and the release structure 4 between the expansion cone assembly 3 and the plug-in socket 5 is reversed and released to remove the inner pipe column, thereby realizing the emergency reverse release function of the tool.

[0030] According to the above working principle, some preferred implementation structures and implementation methods are further provided, specifically as follows Figure 2 As shown, the plug connector 6 and the plug socket 5 are mutually matched and plugged pipe columns, and the matching connection between the two pipe columns is a stepped cylindrical surface, and the diameter of the stepped cylindrical surface of the plug connector 6 near the plug socket 5 increases successively, and the maximum diameter is smaller than the diameter of the expansion pipe 1. This facilitates the buckling between the two, and also facilitates the straightening and guiding of the plug oil pipe 8 and the expansion cone assembly 3.

[0031] like Figure 3 As shown, the mating surface of the connection between the plug-in oil pipe 8 and the plug-in connector 6 is a stepped cylindrical surface, which is convenient for the clamping connection between the two.

[0032] like Figure 5 As shown, the release structure 4 includes mutually connected reverse-rotation thread structures respectively arranged on the inner wall surface of the expansion cone assembly 3 and the outer wall surface of the plug-in socket 5, and the reverse-rotation thread structure is disengaged when the plug-in socket 5 rotates clockwise. This facilitates the reverse-rotation release of the thread on the inner wall surface of the expansion cone assembly 3 without affecting the locking of other normal threads.

[0033] The release structure 4 may also include a shearable pin and a pin hole respectively arranged on the inner wall surface of the expansion cone assembly 3 and the outer wall surface of the plug-in socket 5 and engaging with each other. This structure can also realize the release operation of the expansion cone assembly 3, as long as the shear pin with appropriate shear force breaks when the expansion of the expansion tube 1 is blocked and exceeds a certain upward shear force, the release is realized.

[0034] One end of the bottom plug 2 is sealed and connected to the prefabricated expansion chamber 11 through a sealing ring, and the other end is connected to the prefabricated expansion chamber 11 through a shearable thread. In this way, during the expansion process, one end of the expansion tube 1 and the bottom plug 2 can be completely sealed, which is convenient for pumping liquid and pressurizing, and the shearable thread is convenient for the recovery of the bottom plug 2.

[0035] The clamping ring structure 7 includes a male buckle and a female buckle respectively arranged on the plug socket 5 and the plug connector 6, and the male buckle and the female buckle are locked with each other after the plug socket 5 and the plug connector 6 are plugged in. This facilitates the plug socket 5 and the plug connector 6 to be quickly locked after being plugged in.

[0036] The male buckle is a bayonet pin and the female buckle is a slot. This snap ring method is simple and can also prevent disengagement under external force after buckling.

[0037] The plug connector 6 is threadedly connected to the plug oil pipe 8. This facilitates the detachable connection between the two, thereby facilitating the plug oil pipe 8 to be inserted after multiple assembly.

[0038] like Figure 1 As shown, multiple groups of combined rubbers 9 are connected to the outer wall of the expansion tube 1, and the combined rubbers 9 are used to seal and support the expansion tube 1 in the casing 0. In this way, multi-stage sealing can be achieved, making the sealing stronger to withstand higher working pressure.

[0039] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. 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 can be combined in any one or more embodiments or examples in a suitable manner.

[0041] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. An expandable pipe string structure for wellbore reconstruction, comprising an expandable pipe (1), a bottom plug (2) and an expansion cone assembly (3), wherein the expansion cone assembly (3) and the bottom plug (2) are sequentially arranged in a prefabricated expansion cavity (11) expanded outwardly at the end of the expandable pipe (1), and the expansion cone assembly (3) and the bottom plug (2) are slidably sealed with the cavity wall of the prefabricated expansion cavity (11), and the bottom plug (2) is sealed for closing the prefabricated expansion cavity (11), characterized in that: The expansion cone assembly (3) is internally connected to one end of a plug-in socket (5) via a release structure (4), the release structure (4) being used to release the expansion cone assembly (3), the other end of the plug-in socket (5) being connected to one end of a plug-in connector (6), the plug-in socket (5) and the plug-in connector (6) being connected via a clamping ring structure (7), the other end of the plug-in connector (6) being detachably connected to a plug-in oil pipe (8).

2. The expandable pipe string structure for wellbore reconstruction according to claim 1, characterized in that: The plug-in joint (6) and the plug-in socket (5) are mutually matched and plugged pipe columns, and the mutually matched connection point of the two pipe columns is a stepped cylindrical surface. The diameter of the stepped cylindrical surface of the plug-in joint (6) close to one end of the plug-in socket (5) increases successively, and the maximum diameter is smaller than the diameter of the expansion pipe (1).

3. The expandable pipe string structure for wellbore reconstruction according to claim 1, characterized in that: The mating surface at the connection between the plug-in oil pipe (8) and the plug-in joint (6) is a stepped cylindrical surface.

4. The expandable pipe string structure for wellbore reconstruction according to claim 1, characterized in that: The release structure (4) comprises mutually connected reverse-rotation thread structures respectively arranged on the inner wall surface of the expansion cone assembly (3) and the outer wall surface of the plug-in socket (5), and the reverse-rotation thread structures are disengaged when the plug-in socket (5) rotates clockwise.

5. The expandable pipe string structure for wellbore reconstruction according to claim 1, characterized in that: The release structure (4) comprises a shearable pin and a pin hole which are respectively arranged on the inner wall surface of the expansion cone assembly (3) and the outer wall surface of the plug-in socket (5) and engage with each other.

6. The expandable pipe string structure for wellbore reconstruction according to claim 1, characterized in that: One end of the bottom plug (2) is sealedly connected to the prefabricated expansion chamber (11) via a sealing ring, and the other end is connected to the prefabricated expansion chamber (11) via a shearable thread.

7. The expandable pipe string structure for wellbore reconstruction according to claim 1, characterized in that: The clamping ring structure (7) comprises a male buckle and a female buckle respectively arranged on the plug-in socket (5) and the plug-in connector (6), and the male buckle and the female buckle are locked with each other after the plug-in socket (5) and the plug-in connector (6) are plugged together.

8. The expandable pipe string structure for wellbore reconstruction according to claim 7, characterized in that: The male buckle is a bayonet pin, and the female buckle is a slot.

9. The expandable pipe string structure for wellbore reconstruction according to claim 1, characterized in that: The plug-in connector (6) and the plug-in oil pipe (8) are connected via threads.

10. The expandable pipe string structure for wellbore reconstruction according to claim 1, characterized in that: A plurality of groups of combined rubbers (9) are connected to the outer wall of the expansion tube (1), and the combined rubbers (9) are used to seal and support the expansion tube (1) in the casing (0).

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