Packer for tubular column and integrated tubular column

Abstract

The invention relates to a packer for a tubular column and an integrated tubular column. The packer comprises a central shaft tube, an expansion cone and an expansion sleeve. The center shaft tube is provided with a limiting piece protruding out of the inner wall of the center shaft tube. The expansion cone is connected to the outer portion of the central shaft pipe in a sleeving mode and is configured to be capable of forming axial limiting with the limiting piece. The expansion sleeve is arranged outside the central shaft tube in a sleeving mode and located below the expansion cone. And the limiting piece is constructed to be capable of pushing the expansion cone to move downwards, so that the expansion cone can enable the expansion sleeve to deform outwards in the radial direction. The contact stress between the expansion cone and the expansion sleeve is certainly greater than the yield stress of the expansion sleeve, so that the interference fit between the deformed expansion sleeve and the sleeve is ensured, and enough reliable sealing can be formed between the expansion sleeve and the sleeve.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas well development, and particularly relates to a packer for a pipe string and an integrated pipe string. BACKGROUND

[0002] In recent years, with the vigorous development of unconventional oil and gas resources, in order to improve the oil and gas production, the types of well types such as deep well, ultra-deep well, high-deviation well, long horizontal well and the like gradually increase. The packer is a key downhole tool for oil and gas field development, and is mainly used for implementing separate layer acidizing, separate layer fracturing, separate layer water injection, separate layer gas production, separate layer testing and the like. With the increase of well depth, the complex working conditions such as high temperature, high pressure and high hydrogen sulfide content bring more stringent use environment to the packer. At present, the conventional packer mostly uses high-elasticity rubber as a sealing element, and basically can meet the requirements of well conditions with temperature less than 120 DEG C and pressure less than 70 MPa. However, for well conditions with temperature greater than 150 DEG C and pressure level greater than 70 MPa, it is difficult to fully meet the needs of the field.

[0003] In addition, after some low-permeability oil and gas reservoirs such as shale gas wells are subjected to hydraulic fracturing, the phenomenon of fracture closure is prone to occur in the later oil and gas production, thereby leading to the decrease of oil and gas production. Repeated fracturing is one of the effective ways to improve the production of oil and gas wells and prolong the life of oil and gas wells. With the exhaustion of oil and gas in the already mined reservoir interval, through repeated fracturing, the hydraulic fracturing of new production layers can be performed by means of the same wellbore condition, so as to obtain the oil and gas production. In view of the size limitation of the wellbore of the existing wellbore, it is difficult to realize large-displacement and large-scale repeated fracturing by using the conventional packer in cooperation with the sliding sleeve to perform the hydraulic fracturing of the new production layers. SUMMARY

[0004] Based on the above problems existing in the prior art, the present application provides a packer for a pipe string, which can form a very reliable seal with a casing under high temperature and high pressure conditions downhole. The packer is used in cooperation with a full-bore sliding sleeve, and can meet the multi-stage staged fracturing reconstruction of an integrated pipe string.

[0005] In a first aspect, the present application provides a packer for a pipe string, comprising,

[0006] a center shaft pipe, which is provided with a limiting piece protruding from the inner wall of the center shaft pipe in an initial state;

[0007] an expansion cone, which is sleeved on the outside of the center shaft pipe and is configured to form axial limitation with the limiting piece; and

[0008] an expansion sleeve, which is sleeved on the outside of the center shaft pipe and is located below the expansion cone,

[0009] The limiting member is configured to push the expansion cone downward under the pressure of the pressure buildup inside the tubing, so that the expansion cone causes the expansion sleeve to deform radially outward, so that the expansion sleeve and the sleeve disposed outside the packer form a sealing fit.

[0010] Furthermore, the central shaft tube has an axially extending strip-shaped hole, which is configured to partially receive the limiting member so that the limiting member can only move downward along the strip-shaped hole.

[0011] Furthermore, the expansion cone has a receiving hole that is radially aligned with the strip hole, for partially receiving the limiting member, so that the limiting member and the expansion cone form an axial limit, thereby enabling the expansion cone to move downward.

[0012] Furthermore, it also includes an upper connector sleeved on the upper end of the central shaft tube, the inner wall of the upper connector having a groove, the limiting member being configured to move radially outward and at least partially enter the groove when the expansion cone moves downward to make the receiving hole and the groove radially aligned, so that it no longer protrudes from the inner wall of the central shaft tube.

[0013] Furthermore, the limiting member includes a limiting portion and a supporting portion connected to the limiting portion and housed within the receiving hole, wherein the limiting portion is configured to form a clearance fit with the wall of the strip hole and protrude from the inner wall of the central shaft tube.

[0014] Furthermore, it also includes a lower connector sleeved at the lower end of the central shaft tube, and a bidirectional anchoring member sleeved on the outside of the central shaft tube is provided between the lower connector and the expansion sleeve.

[0015] The bidirectional anchor is configured to expand radially outward when the expansion sleeve moves downward, and to form an axial limit with the sleeve.

[0016] Furthermore, the upper end of the lower connector and the lower end of the expansion sleeve are both set in a conical shape so that when the expansion sleeve moves downward, the upper end of the lower connector and the lower end of the expansion sleeve can guide the bidirectional anchor to expand radially outward.

[0017] Furthermore, the expansion cone is configured to push the expansion sleeve downward when the contact stress between it and the expansion sleeve is less than the yield stress of the expansion sleeve.

[0018] Furthermore, it is configured such that when the bidirectional anchoring member forms an axial limit with the sleeve, the contact stress between it and the expansion sleeve increases to a level greater than the yield stress of the expansion sleeve, thereby causing the expansion sleeve to deform.

[0019] Furthermore, the lower end of the expansion cone is provided with a compression part, which is configured to be inserted into the gap between the expansion sleeve and the central shaft tube, so as to cause the expansion sleeve to deform radially outward.

[0020] Furthermore, a first ratchet is provided on the outer wall of the central shaft tube, and a second ratchet is provided on the inner wall of the expansion cone, which can engage with the first ratchet, so that the expansion cone can only move axially downward relative to the central shaft tube.

[0021] Furthermore, the pressure is generated by engaging the sealing ball with the limiting member.

[0022] A second aspect of the present invention provides an integrated tubular column, comprising a plurality of packers as described above, a plurality of sliding sleeves spaced apart from each corresponding packer, and a setting ball.

[0023] The setting ball is configured to pass through several packers and several sliding sleeves in sequence to achieve the full bore of the tubing.

[0024] The beneficial effects of this invention are as follows: This invention provides a packer for a tubular column, comprising a central shaft tube, an expansion cone, and an expansion sleeve. The central shaft tube is fitted with a limiting member protruding from its inner wall. The expansion cone is sleeved on the outside of the central shaft tube and configured to axially limit the expansion with the limiting member. The expansion sleeve is sleeved on the outside of the central shaft tube and located below the expansion cone. The limiting member is configured to push the expansion cone downwards, causing the expansion cone to deform the expansion sleeve radially outwards. The deformed expansion sleeve and the sleeve form a sealing fit, thus creating a seal between them.

[0025] Therefore, in this application, the force required to cause plastic deformation of the expansion sleeve is converted into the force required for the setting ball to push the limiting element downward to the groove. The setting ball is pressurized within the packer so that the pressure inside the wellbore rises sufficiently for the pressure difference across the setting ball to push the limiting element downward to the groove. This ensures that the contact stress between the expansion cone and the expansion sleeve is greater than the yield stress of the expansion sleeve, thereby ensuring a sufficiently reliable seal between the expansion sleeve and the casing.

[0026] Furthermore, the packer and full-bore sliding sleeve provided by this invention can form a large-channel, full-bore integrated tubing string. Theoretically, the packer and sliding sleeve can be connected in an unlimited series, thus facilitating single-stage or multi-stage fracturing stimulation of specific reservoirs. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Figure 1 The diagram shown is a structural schematic of an integrated tubular column.

[0029] Figure 2 The diagram shows the initial state of the setting ball within the packer.

[0030] Figure 3 As shown Figure 2 The image shows a magnified view of the setting ball in its initial state within the packer.

[0031] Figure 4 The diagram shown is a structural plan view of the limiting component from one perspective.

[0032] Figure 5 As shown Figure 4 The structural plan view of the limiting component shown from another perspective.

[0033] Figure 6 The image shown is a partial enlarged view after the packer has been set.

[0034] Figure 7 The diagram shown is a schematic of the sliding sleeve.

[0035] In the figures, the following reference numerals are used: 1. Integrated tubular column; 100. Packer; 10. Central shaft tube; 11. Limiting element; 111. Limiting part; 112. Supporting part; 12. Strip hole; 13. First ratchet; 20. Upper connector; 21. Groove; 22. Shear pin; 30. Lower connector; 40. Expansion cone; 41. Receiving hole; 42. Extrusion part; 43. First sealing ring; 44. Second sealing ring; 45. Mounting groove; 46. Snap ring; 461. Second ratchet; 50. Expansion sleeve; 51. Clearance; 60. Bidirectional anchoring element;

[0036] 200. Seat and block;

[0037] 300, Sliding sleeve; 301, Inner cylinder; 3011, Gear groove; 302, Outer cylinder; 3021, Connecting hole; 3022, Shear pin; 303, First connector; 304, Second connector;

[0038] 400, sleeve. Detailed Implementation

[0039] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will now be described in detail with reference to the accompanying drawings. This drawing is a simplified schematic diagram, illustrating only the basic structure of the invention, and therefore only shows the components relevant to the invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] refer to Figure 1 and Figure 2 As shown, the integrated tubing string 1 provided by this invention includes at least a plurality of packers 100 and a plurality of sliding sleeves 300 arranged at intervals with the packers 100. Theoretically, the packers 100 and sliding sleeves 300 can be connected in series at infinite intervals to form an infinite number of fracturing tubing strings. The sliding sleeves 300 are preferably full-bore sliding sleeves. When the setting ball 200 is inserted into the integrated tubing string 1 from the wellhead, it is pumped into the first packer 100 and encounters resistance. After pressurizing and setting the first packer 100, the setting ball 200 can pass through the first packer 100, and then through the first full-bore sliding sleeve 300 to enter the second packer 100. This process continues, with the setting ball 200 sequentially setting several packers 100 until the setting ball 200 is pumped to the bottom of the well. Thus, a full-bore integrated tubing string 1 is obtained. After the opening tool (not shown) is inserted into the integrated tubing string 1 from the wellhead, it is pumped into the corresponding sliding sleeve 300. The opening tool can engage and disengage the corresponding sliding sleeve 300, thereby enabling fracturing and stimulation operations. In this application, the direction of the axis of the integrated tubing string 1 is defined as axial, and the direction of the diameter of the integrated tubing string 1 is defined as radial. Furthermore, the direction toward the wellhead is defined as upward, and the direction toward the bottom of the well is defined as downward.

[0041] refer to Figure 2As shown, in some embodiments, the packer 100 includes a central shaft tube 10, an upper connector 20 and a lower connector 30 respectively disposed at the upper and lower ends of the central shaft tube 10, and an expansion cone 40, an expansion sleeve 50, and a bidirectional anchoring member 60 sleeved outside the central shaft tube 10. A limiting member 11 is provided between the central shaft tube 10 and the expansion cone 40, which protrudes from the inner wall of the central shaft tube 10 in the initial state, so that the setting ball 200 entering the packer 100 can be limited by the limiting member 11. Under the action of high-pressure fluid being transported at the wellhead, the setting ball 200 can push the expansion cone 40 to move axially downward through the limiting member 11. The expansion sleeve 50 moves axially downward under the action of the expansion cone 40, and then cooperates with the lower connector 30 to cause the bidirectional anchoring member 60 to expand radially outward, so that the bidirectional anchoring member 60 can form a bidirectional anchoring with the casing 400 of the oil and gas well. Under the impetus of high-pressure fluid, the setting ball 200 continues to push the expansion cone 40 axially downward through the limiting member 11. The expansion cone 40 extends into the gap 51 between the expansion sleeve 50 and the central shaft tube 10 and squeezes the expansion sleeve 50 radially outward, causing the expansion sleeve 50 to deform radially outward, thereby allowing the packer 100 to contact the casing 400 of the oil and gas well (see...). Figure 6 An interference fit is used. This ensures a very reliable seal between the packer 100 and the casing 400 of the oil and gas well.

[0042] refer to Figure 3 As shown, in some embodiments, a strip-shaped hole 12 is provided on the side wall of the central shaft tube 10, extending axially. The strip-shaped hole 12 is located near one end of the upper connector 20 and extends radially through the central shaft tube 10 to accommodate and circumferentially limit the limiting member 11, allowing the limiting member 11 to move axially along the strip-shaped hole 12. The strip-shaped hole 12 also provides radial limitation for the limiting member 11 to prevent it from entering the central shaft tube 10. The limiting member 11 is configured to protrude radially inward from the inner wall of the central shaft tube 10 in its initial state, causing the central shaft tube 10 to narrow at the limiting member 11, thereby providing axial downward limitation for the setting ball 200. In some preferred embodiments, multiple strip-shaped holes 12 are provided, and these holes 12 are evenly arranged circumferentially around the central shaft tube 10. The limiting elements 11 within the multiple slots 12 together form an axial limit on the setting ball 200, enabling the setting ball 200 to uniformly transmit the thrust to the expansion cone 40 through the multiple limiting elements 11.

[0043] In some embodiments, the wall of the slot 12 is arc-shaped so that it can fit well against the surface of the spherical retaining member 11. This avoids the formation of a large gap between the slot 12 and the retaining member 11, preventing a reduction in the thrust on the set ball 200 due to high-pressure fluid passing through the gap.

[0044] In some preferred embodiments, the walls of the slot 12 are straight to facilitate machining. (See reference) Figure 4 and Figure 5 As shown, the limiting member 11 has an irregular structure, including a limiting part 111 and a supporting part 112 connected to the limiting part 111. The limiting part 111 can pass through the slotted hole 12 and protrude radially inward from the inner wall of the central shaft tube 10 to limit the seat ball 200 axially downward. The side wall of the limiting part 111 can form a clearance fit with the inner wall of the slotted hole 12, thereby minimizing the gap between the slotted hole 12 and the limiting member 11 as much as possible without affecting the movement of the limiting member 11 along the slotted hole 12. The supporting part 112 can form an axial limit with the expansion cone 40 to push the expansion cone 40 to move axially downward. The end face between the limiting part 111 and the supporting part 112 can abut against the outer wall of the central shaft tube 10 to limit the limiting member 11 radially inward, so as to prevent the limiting member 11 from falling into the central shaft tube 10.

[0045] In some embodiments, a first ratchet 13 is also provided on the side wall of the central shaft tube 10. The first ratchet 13 can provide a one-way upward axial limit for the expansion cone 40, so that the expansion cone 40 can only move downward axially relative to the central shaft tube 10.

[0046] Combination Figure 2 and Figure 3 As shown, in some embodiments, the expansion cone 40 is generally a hollow tubular structure open at both ends. The upper end of the expansion cone 40 is fitted between the central shaft tube 10 and the upper connector 20. A receiving hole 41, radially penetrating and radially aligned with the strip hole 12, is provided on the side wall of the upper end of the expansion cone 40. The receiving hole 41 accommodates the abutment portion 112 of the limiting member 11, allowing the limiting member 11 to form an axial limit with the expansion cone 40, thereby transmitting force. Thus, the setting ball 200 can push the expansion cone 40 downward through the limiting member 11. A groove 21, radially aligned with the strip hole 12, is provided on the inner wall of the upper connector 20. The groove 21 and the receiving hole 41 are arranged axially along the strip hole 12, and in the initial state, the groove 21 is located below the receiving hole 41. Furthermore, a shear pin 22 for temporary fixation is provided between the upper connector 20 and the expansion cone 40.

[0047] In some embodiments, under the action of high-pressure fluid, the setting ball 200 pushes the expansion cone 40 downward through the limiting member 11 to shear the shear pin 22. Subsequently, the setting ball 200, the limiting member 11, and the expansion cone 40 move downward together, and the expansion sleeve 50 also moves axially downward under the action of the expansion cone 40, thereby causing the bidirectional anchoring member 60 to expand radially outward. When bidirectional anchoring is formed between the bidirectional anchoring member 60 and the sleeve 400 and the expansion sleeve 50 deforms radially outward, the expansion cone 40 moves downward until the receiving hole 41 and the groove 21 are radially aligned, such as... Figure 6 As shown. At this time, under the action of the setting ball 200, the abutting portion 112 of the limiting member 11 enters the groove 21 radially outward, so that the end of the limiting portion 111 of the limiting member 11 no longer protrudes from the inner wall of the central shaft tube 10. As a result, the axial limitation between the setting ball 200 and the limiting member 11 disappears, and the setting ball 200 can pass through the packer 100 to enter the lower sliding sleeve 300.

[0048] Combination Figure 3 and Figure 6 As shown, in some embodiments, the lower end of the expansion cone 40 is provided with a tapered extrusion portion 42, which extends into the gap 51 between the expansion sleeve 50 and the central shaft tube 10. During the downward movement of the expansion cone 40, and guided by the expansion of the tapered outer surface of the extrusion portion 42, the expansion sleeve 50 undergoes radial outward deformation. The outer wall of the deformed expansion sleeve 50 forms a sealing fit with the casing 400 of the oil and gas well, thereby creating a reliable seal between the packer 100 and the casing 400 of the oil and gas well.

[0049] In some embodiments, a first sealing ring 43 is provided between the outer wall of the expansion cone 40 and the inner wall of the upper connector 20, thereby forming a seal between the expansion cone 40 and the upper connector 20. A second sealing ring 44 is also provided between the inner wall of the extrusion portion 42 of the expansion cone 40 and the outer wall of the central shaft tube 10, thereby forming a seal between the expansion cone 40 and the central shaft tube 10. The second sealing ring 44 is located below the first ratchet 13, so that the second sealing ring 44 does not need to pass through the first ratchet 13 during the downward movement of the expansion cone 40, thus ensuring the integrity of the second sealing ring 44.

[0050] In some embodiments, the inner wall of the expansion cone 40 is further provided with a mounting groove 45, and a retaining ring 46 is provided in the mounting groove 45. The inner surface of the retaining ring 46 is provided with a second ratchet 461 corresponding to the first ratchet 13. The second ratchet 461 can form a one-way limit with the first ratchet 13 in the axial upward direction, so that the expansion cone 40 can only move axially downward relative to the central shaft tube 10.

[0051] refer to Figure 6As shown, in some embodiments, the expansion sleeve 50 is made of an expandable, highly ductile metal material, such as highly ductile titanium alloys, copper alloys, aluminum alloys, and stainless steel. In some embodiments, the outer surface of the expansion sleeve 50 may also be grooved to install O-rings for auxiliary sealing, or rubber components may be installed or vulcanized to improve the reliability of the seal.

[0052] Combination Figure 2 and Figure 6 As shown, in some embodiments, the lower end of the expansion sleeve 50 and the upper end of the lower connector 30 are both tapered. When the expansion sleeve 50 moves downward, the lower end of the expansion sleeve 50 and the upper end of the lower connector 30 can be inserted between the bidirectional anchoring member 60 and the central shaft tube 10 and guide the bidirectional anchoring member 60 to expand radially outward, so that the bidirectional anchoring member 60 can form a bidirectional anchor with the casing 400 of the oil and gas well. In some embodiments, the bidirectional anchoring member 60 can be a cylindrical bidirectional slip, a C-ring bidirectional slip, or a friction block bidirectional slip.

[0053] refer to Figure 7 As shown, in some embodiments, the sliding sleeve 300 includes an inner cylinder 301, an outer cylinder 302 sleeved around the inner cylinder 301, and a first connector 303 and a second connector 304 sealed to the outer cylinder 302. The first connector 303 is used to connect to the lower connector 30 of the tubing or packer 100, and the second connector 304 is used to connect to the upper connector 20 of the tubing or packer 100. The outer cylinder 302 has several through holes 3021 for conveying fracturing fluid to the external annulus of the sliding sleeve 300. The outer cylinder 302 is also provided with shear pins 3022 for temporary fixation to the inner cylinder 301. The inner wall of the inner cylinder 301 is provided with several different toothed grooves 3011 for axially limiting the opening tool corresponding to the sliding sleeve 300. The opening tool for opening the sliding sleeve 300 is well known to those skilled in the art and will not be described in detail here.

[0054] Combination Figure 2 , Figure 3 and Figure 6As shown, the fracturing process of an integrated tubing string 1 provided by this invention is as follows: After the setting ball 200 is inserted into the integrated tubing string 1 from the wellhead, it is pumped into the first packer 100 and forms an axial limit with the limiting member 11. Then, pressure is applied, causing the pressure inside the wellbore to rise. Under the pressure difference between the upper and lower ends, the setting ball 200 pushes the expansion cone 40 to shear the shear pin 22 through the limiting member 11, thereby causing the expansion cone 40 to move downward. Since the bidirectional anchoring member 60 has not yet formed a bidirectional anchor with the casing 400 at this time, and the contact stress between the extrusion part 42 of the expansion cone 40 and the expansion sleeve 50 is less than the yield strength of the expansion sleeve 50, the extrusion part 42 of the expansion cone 40 can push the expansion sleeve 50 downward. Under the guidance of the lower end of the expansion sleeve 50 and the upper end of the lower connector 30, the bidirectional anchoring member 60 expands radially outward and forms a bidirectional anchor with the casing 400. The pressure continues to build up, causing the pressure difference between the upper and lower ends of the setting ball 200 to increase further. The setting ball 200 continues to push the expansion cone 40 downward through the limiting member 11. The contact stress between the pressing part 42 of the expansion cone 40 and the expansion sleeve 50 gradually increases until it exceeds the yield stress of the expansion sleeve 50, causing the expansion sleeve 50 to undergo plastic deformation. The deformed expansion sleeve 50 and the sleeve 400 have an interference fit, allowing a seal to be formed between the expansion sleeve 50 and the sleeve 400.

[0055] When the expansion cone 40 moves downward until the receiving hole 41 and the groove 21 are radially aligned, the setting ball 200 pushes the limiting member 11 radially outward, causing the limiting member 11 to enter the groove 21. At this time, the end of the limiting portion 111 of the limiting member 11 no longer protrudes from the inner wall of the central shaft tube 10, thus no longer restricting the setting ball 200.

[0056] During the movement of the limiting member 11 to the groove 21, the pressure inside the wellbore rises to its maximum due to the continuous pressure build-up of the setting ball 200 within the packer 100. At this time, the contact stress between the compression portion 42 of the expansion cone 40 and the expansion sleeve 50 is much greater than the yield stress of the expansion sleeve 50, ensuring a sufficiently reliable seal between the expansion sleeve 50 and the casing 400. Therefore, this invention can convert the force required to cause plastic deformation of the expansion sleeve 50 into the force required for the setting ball 200 to push the limiting member 11 downward to the groove 21. In other words, the setting ball 200 is pressed up within the packer 100 to raise the pressure inside the wellbore to a sufficiently high level, so that the pressure difference across the two ends of the setting ball 200 can push the limiting member 11 downward to the groove 21. This ensures that the contact stress between the expansion cone 40 and the expansion sleeve 50 is greater than the yield stress of the expansion sleeve 50, thereby ensuring a sufficiently reliable seal between the expansion sleeve 50 and the casing 400.

[0057] When the limiting member 11 no longer protrudes from the inner wall of the central shaft tube 10, the restriction on the setting ball 200 by the limiting member 11 disappears. Thus, the setting ball 200 can continue to move downwards under the pressure difference, passing through the sliding sleeve 300 located below the packer 100, and entering the second packer 100. The setting process can then be repeated. This cycle is repeated to achieve the setting of multiple packers 100.

[0058] Under the action of high-pressure fluid inside the wellbore, the setting ball 200 sequentially sets several packers 100 on the integrated tubing string 1 until the setting ball 200 is delivered to the bottom of the well by the high-pressure fluid. At this time, the limiting elements 11 of the packers 100 no longer protrude from the inner wall of the central shaft tube 10, and the sliding sleeves 300 are all full-bore sliding sleeves, making the integrated tubing string 1 full-bore, thereby obtaining a large-channel, full-bore construction channel.

[0059] One or more specific opening tools are inserted from the wellhead into the integrated tubing string 1 and delivered into the corresponding sliding sleeve 300. The opening tools are axially confined by the grooves 3011 of the inner sleeve 301. Continued pressure application causes the opening tools to push the inner sleeve 301, cutting off the shear pin 3022 and moving the inner sleeve 301 downwards. When the lower end of the inner sleeve 301 abuts against the upper end face of the second connector 304, the upper end of the inner sleeve 301 is located at the lower end of the connecting hole 3021, allowing the connecting hole 3021 to connect the interior and exterior annulus of the sliding sleeve 300. This allows for single-stage or multi-stage fracturing stimulation of a specific reservoir.

[0060] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0061] It should be understood that the terms "length", "width", "up", "down", "front and back", "left and right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0062] The above description, based on the preferred embodiments of the present invention, provides guidance. Those skilled in the art can make various changes and modifications without departing from the scope of the invention. The technical scope of this invention is not limited to the contents of the specification but must be determined according to the claims.

Claims

1. A packer for a tubular string, comprising: The central shaft tube (10) is equipped with a limiting member (11) that protrudes from the inner wall of the central shaft tube (10) in the initial state; An expansion cone (40) is fitted onto the outside of the central shaft tube (10) and configured to axially limit the movement of the limiting member (11); and An expansion sleeve (50) is fitted over the outside of the central shaft tube (10) and located below the expansion cone (40). in, The limiting member (11) is configured to push the expansion cone (40) downward under the pressure of the accumulating pressure in the tubing (1), so that the expansion cone (40) causes the expansion sleeve (50) to deform radially outward, so that the expansion sleeve (50) and the sleeve (400) disposed outside the packer (100) form a sealing fit.

2. The packer for tubular strings according to claim 1, characterized in that, The central shaft tube (10) has an axially extending strip hole (12) configured to partially receive the limiting member (11) so that the limiting member (11) can only move downward along the strip hole (12).

3. The packer for tubular strings according to claim 2, characterized in that, The expansion cone (40) has a receiving hole (41) that is radially aligned with the strip hole (12) for partially receiving the limiting member (11), so that the limiting member (11) and the expansion cone (40) form an axial limit, thereby enabling the expansion cone (40) to move downward.

4. The packer for tubular strings according to claim 3, characterized in that, It also includes an upper connector (20) sleeved on the upper end of the central shaft tube (10), the inner wall of the upper connector (20) having a groove (21), the limiting member (11) being configured to move radially outward and at least partially enter the groove (21) when the expansion cone (40) moves downward to make the receiving hole (41) and the groove (21) radially aligned, so that it no longer protrudes from the inner wall of the central shaft tube (10).

5. The packer for tubular strings according to claim 3, characterized in that, The limiting member (11) includes a limiting part (111) and a supporting part (112) connected to the limiting part (111) and housed in the receiving hole (41), wherein the limiting part (111) is configured to form a clearance fit with the hole wall of the strip hole (12) and protrude from the inner wall of the central shaft tube (10).

6. The packer for tubular strings according to claim 1, characterized in that, It also includes a lower connector (30) sleeved at the lower end of the central shaft tube (10), and a bidirectional anchoring member (60) sleeved on the outside of the central shaft tube (10) is provided between the lower connector (30) and the expansion sleeve (50). The bidirectional anchor (60) is configured to expand radially outward when the expansion sleeve (50) moves downward, and to form an axial limit with the sleeve (400).

7. The packer for tubular strings according to claim 6, characterized in that, The upper end of the lower connector (30) and the lower end of the expansion sleeve (50) are both set in a conical shape so that when the expansion sleeve (50) moves downward, the upper end of the lower connector (30) and the lower end of the expansion sleeve (50) can guide the bidirectional anchor (60) to expand radially outward.

8. The packer for tubular strings according to claim 6, characterized in that, The expansion cone (40) is configured to push the expansion sleeve (50) downward when the contact stress between it and the expansion sleeve (50) is less than the yield stress of the expansion sleeve (50). Furthermore, it is configured such that when the bidirectional anchor (60) forms an axial limit with the sleeve (400), the contact stress between it and the expansion sleeve (50) increases to a level greater than the yield stress of the expansion sleeve (50), so that the expansion sleeve (50) deforms.

9. The packer for tubular strings according to claim 1, characterized in that, The lower end of the expansion cone (40) is provided with a pressing part (42), which is configured to be inserted into the gap (51) between the expansion sleeve (50) and the central shaft tube (10) so that the expansion sleeve (50) deforms radially outward.

10. The packer for tubular tubing according to claim 1, characterized in that, The outer wall of the central shaft tube (10) is provided with a first ratchet (13), and the inner wall of the expansion cone (40) is provided with a second ratchet (461) that can engage with the first ratchet (13), so that the expansion cone (40) can only move axially downward relative to the central shaft tube (10).

11. The packer according to any one of claims 1 to 10, characterized in that, The pressure is generated by the engagement of the seat ball (200) with the limiting member (11).

12. An integrated tubular string comprising a plurality of packers (100) as described in any one of claims 1 to 11, a plurality of sliding sleeves (300) spaced apart from each corresponding packer (100), and a setting ball (200). in, The setting ball (200) is configured to pass through a plurality of the packers (100) and a plurality of the sliding sleeves (300) in sequence to achieve the full bore of the string (1).

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