Drilling liner hanger slip retaining system and method

Abstract

The invention belongs to the field of petroleum and natural gas well cementation tools, particularly relates to a drilling liner hanger slip retaining system and method, and aims to solve the problem that a drilling liner hanger slip retaining system in the prior art is prematurely set or slips fall off. The system comprises a mandrel, a taper sleeve, a taper slip, a retaining ring and a hydraulic actuating mechanism, one end of the mandrel is connected with a tripping-in tool, the other end of the mandrel is connected with a taper sleeve bearing, a plurality of taper grooves are evenly formed in the outer surface of the taper sleeve in the axial direction of the taper sleeve, taper slips are slidably connected into the taper grooves, a plurality of teeth are evenly arranged on the outer surfaces of the taper slips in the length direction of the taper slips, and the teeth are connected with the inner surface of a casing pipe in a clamped mode; the conical slip is meshed with the retaining ring, the retaining ring is driven by the hydraulic executing mechanism, and the hydraulic executing mechanism can slide at the axial end of the retaining ring so as to prevent the conical slip from accidentally falling off after the conical slip is set along the outer portion of the conical sleeve. The slip can be effectively prevented from falling off.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas cementing tools, and particularly relates to a slip holding system and method for a liner hanger. Background Art

[0002] In the application of many wells, a well is drilled and a casing string is run down the wellbore. Then a liner hanger is used to suspend the liner inside the casing string. The liner hanger can be hydraulically operated through a hydraulic cylinder to fix the slip. Once the liner hanger is run into the well and reaches the predetermined position, the slip will be fixed on the surrounding casing string.

[0003] The setting slip is responsible for ensuring sufficient clamping force on the surrounding casing string to bear the weight of the liner and withstand the mechanical and hydraulic loads applied to the system. When the liner hanger is run into the well, the slips should be held in a radially contracted position to avoid premature setting or dropping of the slips.

[0004] Based on this, the present invention proposes a slip holding system and method for a liner hanger. Summary of the Invention

[0005] In order to solve the above problems in the prior art, that is, the problem of premature setting or dropping of the slips in the slip holding system of the prior art liner hanger, the present invention provides a slip holding system and method for a liner hanger.

[0006] On the one hand, the present invention proposes a slip holding system for a liner hanger, the system includes a mandrel, a cone sleeve, a tapered slip, a retaining ring and a hydraulic actuator;

[0007] One end of the mandrel is connected to a running tool and is disposed in the wellbore, the other end of the mandrel is connected to the cone sleeve by a bearing, a tapered groove is formed on the outer surface of the cone sleeve along its axial direction, and multiple groups of the tapered grooves are circumferentially and uniformly distributed along the outer circumferential surface of the cone sleeve. A tapered slip is slidably connected in the tapered groove, and a plurality of teeth are uniformly arranged on the outer surface of the tapered slip along its length direction, and the teeth are clamped and engaged with the inner surface of the casing to achieve fixation;

[0008] The retaining ring has a plurality of fixed fingers that slidably engage the sliding fingers of the tapered slip to prevent the tapered slip from falling out of the retaining ring during the setting of the liner hanger;

[0009] A hydraulic setting mechanism installed around the mandrel to selectively move the tapered slip between a radially contracted position and a radially set position.

[0010] In some preferred embodiments, the tapered slip is slidably engaged with the retaining ring, and its specific structure is:

[0011] The slip cone is provided with slip fingers which are in sliding engagement with a fixed ring finger. The fixed ring finger is disposed on the retaining ring, and the fixed ring finger and the slip fingers are arranged in an interleaved manner.

[0012] In some preferred embodiments, a hammer head is provided at the upper end of the slip cone near the mandrel. The hammer head has an inclined surface to slidably capture the hammer head in a region on the side of the corresponding conical groove near the mandrel. The hammer head is defined to axially slide within the conical groove, and teeth are provided between the hammer head and the slip fingers.

[0013] In some preferred embodiments, the slip cone, the cone sleeve, the retaining ring and the fixed ring finger are processed by at least one of water jet cutting or laser cutting.

[0014] In some preferred embodiments, a fifth angular surface is provided on the conical groove, and the fifth angular surface cooperates with a fourth angular surface which is formed on the slip cone. By the mutually engaging surfaces of the fifth angular surface and the fourth angular surface, the slip cone is prevented from falling off when moving along the cone sleeve.

[0015] In some preferred embodiments, the hydraulic actuator includes a hydraulic cylinder which overlaps on the retaining ring;

[0016] The hydraulic cylinder is provided with an overlapping surface which is in the form of an extended inner diameter of the hydraulic cylinder. The overlapping surface can lap with the edge of the base, and the edge of the base is disposed on the fixed ring finger to prevent the plurality of slip cones from falling off when axially moving during setting.

[0017] In some preferred embodiments, each fixed ring finger is gradually tapered from wide to narrow in the direction from the slip cone to the hydraulic cylinder;

[0018] The axial lengths of every two adjacent fixed ring fingers are different, and the axial lengths of two fixed ring fingers spaced apart by one fixed ring finger distance are the same. Spaces are provided between the plurality of fixed ring fingers and they are arranged at different mating angles to enable the insertion and limitation of the slip fingers of the slip cone.

[0019] In some preferred embodiments, a first angular surface is provided on the fixed ring finger in the circumferential direction, and the first angular surface is interlocked with a second angular surface which is formed on the slip finger.

[0020] In some preferred embodiments, the cone sleeve is configured to be able to mount a plurality of slip cones from the outside of the cone sleeve.

[0021] On the other hand, the present invention proposes a method for holding the tapered slips of a liner hanger, based on a liner hanger tapered slip holding system, the method comprising:

[0022] Position and install a tapered sleeve with a tapered groove on the mandrel of the liner hanger;

[0023] Limit the hammer head at the upper end of each tapered slip within the corresponding tapered groove, and form a sliding interlock through the angular surface of the annular groove and the angular surface of the hammer head;

[0024] Fix the sliding fingers at the lower end of each tapered slip through a retaining ring, and form an engaging interlock through the angular surface of the fixed ring fingers of the retaining ring and the angular surface of the sliding fingers. The fixed ring fingers fix each tapered slip to prevent it from falling off the tapered sleeve;

[0025] Further tighten the tapered slips through the cylinder of the hydraulic actuator for setting the liner hanger, prevent excessive axial movement of the tapered slips, and ensure that the mating inclined surfaces of the tapered slips are held in place.

[0026] Advantages of the present invention:

[0027] By adopting a unique angular combination along the interacting components, when the upper end of each tapered slip engages with the cone, and the lower end of each tapered slip engages with the mating features of the retaining ring, the tapered slips are safely held.

[0028] Configurations with different angles allow the tapered slips to be assembled from the outside or outside of the cone. Each tapered slip can be inserted and screwed into a position relative to the cone and the retaining ring so that the interacting angular surfaces prevent excessive radial movement of the tapered slips from the cone. Once assembled, the hydraulic actuator cylinder can be installed on the retaining ring to prevent the tapered slips from falling off.

[0029] Precision angular mating surfaces formed by water jet cutting or laser cutting processes contribute to the limitation of the tapered slips.

[0030] Bidirectional limitation at the upper and lower ends of the tapered slips further ensures the limitation of the tapered slips and prevents them from falling off during the running-in process. Description of the Drawings

[0031] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objects, and advantages of the present application will become more apparent:

[0032] Figure 1 is a schematic structural diagram of a liner hanger slip holding system of the present invention;

[0033] Figure 2It is a schematic diagram of the setting state of a slip holding system of a liner hanger according to the present invention;

[0034] Figure 3 It is a schematic diagram of the hanging load distribution along the tapered sleeve when the liner hanger of a slip holding system of a liner hanger according to the present invention is set on the surrounding casing;

[0035] Figure 4 It is a schematic diagram of the structure of a tapered slip of a slip holding system of a liner hanger according to the present invention;

[0036] Figure 5 It is a schematic diagram of the structure of a retaining ring of a slip holding system of a liner hanger according to the present invention;

[0037] Figure 6 It is a schematic diagram showing the upper end of the tapered slip of a slip holding system of a liner hanger according to the present invention being engaged with the tapered sleeve and being in the set position;

[0038] Figure 7 It is a schematic diagram showing the lower end of the tapered slip of a slip holding system of a liner hanger according to the present invention being engaged with the retaining ring and being in the set position. Detailed implementation manners

[0039] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the relevant invention and are not intended to limit the invention. Additionally, it should be noted that for the sake of description, only the parts related to the relevant invention are shown in the drawings.

[0040] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0041] As Figures 1 - 7 shown, referring to Figure 1 and Figure 2 , the present invention provides a slip holding system of a liner hanger, which system includes a mandrel 42, a tapered sleeve 44, a tapered slip 52, a retaining ring 54, and a hydraulic actuator 66;

[0042] One end of the mandrel 42 is connected to a running tool and is disposed in a wellbore 36, the other end of the mandrel 42 is in bearing connection with the tapered sleeve 44, a tapered groove 50 is formed on the outer surface of the tapered sleeve 44 along its axial direction, multiple groups of the tapered grooves 50 are circumferentially and uniformly distributed along the outer circumferential surface of the tapered sleeve 44, a tapered slip 52 is slidably connected in the tapered groove 50, a plurality of teeth 70 are uniformly arranged on the outer surface of the tapered slip 52 along its length direction, and the teeth 70 are clamped and engaged with the inner surface of the casing 38 to achieve fixation;

[0043] The retaining ring 54 has a fixed ring finger 58 that slidably engages a plurality of sliding fingers 60 of the tapered slip 52, preventing the tapered slip 52 from falling out of the retaining ring 54 during the setting of the liner hanger.

[0044] A hydraulic setting mechanism 66 mounted around the mandrel 42 selectively moves the tapered slip 52 between a radially contracted position and a radially set position.

[0045] Wherein, the cone sleeve 44 is configured to be able to mount a plurality of tapered slips 52 from the outside of the cone sleeve 44.

[0046] For a further explanation of the present invention, see Figures 3 - 7 , the tapered slip 52 is in sliding engagement with the retaining ring 54, and its specific structure is:

[0047] The tapered slip 52 is provided with sliding fingers 60, the sliding fingers 60 are in sliding engagement with the fixed ring fingers 58, the fixed ring fingers 58 are arranged on the retaining ring 54, and the fixed ring fingers 58 and the sliding fingers 60 are arranged in an interleaved manner.

[0048] For a further explanation of the present invention, see Figure 3 , Figure 4 , Figure 6 , a hammer head 78 is provided at the upper end 72 of the tapered slip 52 near the mandrel 42, the hammer head 78 has an inclined surface 86 to slidably capture the hammer head 78 in a region on the side of the corresponding tapered groove 50 near the mandrel 42, the hammer head 78 is defined to slide axially within the tapered groove 50, and a tooth 70 is provided between the hammer head 78 and the sliding finger 60.

[0049] Wherein, the upper end 72 of the tapered slip 52 is formed into a flared hammer head 78, and the hammer head 78 can be defined under the corresponding third angle surface 96 of the cone sleeve 44.

[0050] Wherein, the retaining ring 54 is used to retain a plurality of tapered slips 52 along the liner hanger 34, the tapered slips 52 are selectively arranged by a hydraulic cylinder 62 mounted around the mandrel 42, the retaining ring 54 is a cylindrical body, and its size is suitable for mounting on the mandrel 42; a plurality of fixed ring fingers 58 extending from the retaining ring 54, spaces 88 are formed between the plurality of fixed ring fingers 58 at different angles to enable the plurality of tapered slips 52 to be inserted and retained; and an overlapping surface 64 of the hydraulic cylinder 62, the size of which is to receive the overlapping part of the hydraulic cylinder 62 to prevent the separation of the plurality of tapered slips 52 after the installation of the liner hanger 34.

[0051] Wherein, the diameter of the overlapping surface 64 of the hydraulic cylinder 62 is smaller than the diameter of the remaining part of the retaining ring 54.

[0052] As a further explanation of the present invention, the processing methods of the tapered slip 52, the tapered sleeve 44, the retaining ring 54, and the fixed finger ring 58 include at least one of water jet cutting or laser cutting.

[0053] As a further explanation of the present invention, refer to Figure 3 , a fifth angle surface 76 is provided on the tapered groove 50, the fifth angle surface 76 cooperates with the fourth angle surface 74, the fourth angle surface 74 is opened on the tapered slip 52, and through the mutual meshing surfaces of the fifth angle surface 76 and the fourth angle surface 74, the tapered slip 52 is prevented from falling off when moving along the tapered sleeve 44.

[0054] As a further explanation of the present invention, refer to Figure 3 , in the circumferential direction of the tapered slip 52, the width of one end close to the retaining ring 54 is greater than the width of one end close to the mandrel 42.

[0055] As a further explanation of the present invention, refer to Figure 1 , Figure 2 , the hydraulic actuator 66 includes a hydraulic cylinder 62, and the hydraulic cylinder 62 overlaps on the retaining ring 54;

[0056] The hydraulic cylinder is provided with an overlapping surface, the overlapping surface is in the form of an extended inner diameter of the hydraulic cylinder, the overlapping surface can overlap with the base edge, and the base edge is provided on the fixed finger ring to prevent the plurality of tapered slips from falling during the lowering process.

[0057] Wherein, the hydraulic cylinder 62 drives the tapered slip 52 to axially move during the setting of the plurality of tapered slips 52.

[0058] Wherein, the hydraulic cylinder 62 is used to prevent the excessive movement of the tapered slip 52 in the axial direction, so as to ensure that the tapered slip 52 is held in place on the sliding cone surface 80.

[0059] As a further explanation of the present invention, refer to Figure 5 , each of the fixed finger rings 58 is gradually arranged from wide to narrow in the direction from the tapered slip 52 to the hydraulic cylinder 62;

[0060] The axial lengths of every two adjacent fixed finger rings 58 are different, the axial lengths of two fixed finger rings 58 separated by one fixed finger ring 58 distance are the same, and there is a space 88 between the plurality of fixed finger rings 58 and they are arranged at different mating angles to enable the sliding fingers 60 of the tapered slip 52 to be inserted and defined.

[0061] As a further explanation of the present invention, refer to Figure 5, the fixing ring finger 58 is provided with a first angular surface 90 upward in the circumferential direction, the first angular surface 90 is interlocked with the second angular surface 84, and the second angular surface 84 is formed on the sliding finger 60.

[0062] As a specific explanation of the first embodiment, Figure 1 The illustrated embodiment of the liner hanger assembly 30 includes a liner hanger 34 and a liner 32 connected thereto. The liner hanger assembly 30 is deployed in the wellbore 36. The liner hanger 34 is in the run-in well position without being set. The liner hanger 34 includes a mandrel 42 having an internal passage, and a bearing 48 is placed between the base 46 and the cone sleeve 44. The cone sleeve 44 includes a plurality of tapered grooves 50 arranged axially along the cone sleeve 44. The tapered grooves 50 are sized to accommodate corresponding hanging slip cones 52. According to the engagement characteristics of the cone sleeve 44 and the slip cone 52 and the parameters of the assembly process, the slip cone 52 can be assembled before or after the cone sleeve 44 is inserted into the mandrel 42.

[0063] The liner hanger 34 further includes a retaining ring 54 that engages the lower end 56 of the slip cone 52 to facilitate holding the slip cone 52 from moving when the liner hanger assembly 30 is run into the wellbore. The retaining ring 54 further includes a plurality of retaining ring fingers 58. The retaining ring fingers 58 are interlocked with a plurality of corresponding sliding fingers 60 located at the lower end 56 of the slip cone 52.

[0064] On the outer side of the retaining ring 54 opposite to the slip cone 52, the retaining ring 54 can be engaged by a hydraulic cylinder 62. The hydraulic cylinder 62 has an overlapping surface 64, and the overlapping surface 64 can be in the form of an extended inner diameter of the hydraulic cylinder 62, and its size is such that it is adjacent to and sleeved outside a portion of the retaining ring 54. Additionally, the hydraulic cylinder 62 is part of a hydraulic actuator 66.

[0065] In the illustrated example, the hydraulic cylinder 62 can be hydraulically driven axially to move the retaining ring 54 until one end face 68 of the hydraulic cylinder 62 is moved to an engagement position adjacent to the lower end 56 of the slip cone 52. The hydraulic cylinder 62 drives the axial movement of the slip cone 52. The axial movement of the slip cone 52 effectively interacts with the cone sleeve 44, forcing the slip cone 52 to move radially outward into the set position. The slip cone 52 and the liner hanger 34 transition from a radially contracted run-in well position to a radially expanded set position.

[0066] In the set position, the teeth 70 of the slip cone 52 are forced into clamping engagement with the inner surface of the surrounding casing 38. The retaining ring fingers 58 and the sliding fingers 60 are designed to allow a certain degree of relative linear movement with respect to each other. During the transition to the set position, the hydraulic cylinder 62 first linearly moves the retaining ring 54 towards the lower end 56 of the slip cone 52, and then engages and linearly moves together with the slip cone 52.

[0067] In Figure 1 and Figure 2 In the illustrated example, the tapered slip 52 is designed as a tapered slip and is slidably receivable in a corresponding tapered groove 50. The tapered slip 52 may taper along its length between an upper end 72 and a lower end 56 such that the upper end 72 is relatively narrow in the circumferential direction such that the lower end 56 of the tapered slip 52 is wider than the opposed upper end 72. Each corresponding tapered groove 50 also has a corresponding taper that extends in the circumferential direction from an upper region of the tapered groove 50 to a lower region of the tapered groove 50. The circumferential side of each tapered slip 52 may have an angular surface 74 that tapers inwardly in a radially inward direction.

[0068] The tapered groove 50 that receives the tapered slip 52 has a corresponding fifth angular surface 76 that circumferentially narrows the tapered groove 50 in a radially inward position relative to a radially outward position. Accordingly, the corresponding taper and the fourth angular surface 74, fifth angular surface 76 are effective to cooperate and force the tapered slip 52 to move in a radially outward direction as the cylinder 62 drives the tapered slip 52 to move linearly relative to the cone sleeve 44 when the cone sleeve 44 is positioned by the base 46. It should be noted that each tapered slip 52 has a hammerhead-shaped hammerhead 78 at its upper end 72 that may hold the tapered slip 52 on the cone sleeve 44 as the liner assembly 30 is run into the well.

[0069] When the liner hanger 34 is run into place, the liner 32 is suspended by the engagement of the liner hanger 34 with the surrounding casing 38. The suspension load generated by the weight of the liner 32 stretches the mandrel 42 downward, and the mandrel 42 in turn acts downward on the cone sleeve 44 through the base 46. As Figure 3 shown, this suspension load is distributed along the angular surfaces, the fourth angular surface 74, fifth angular surface 76 to form a slip cone surface 80. Accordingly, once the liner hanger 34 is set, the suspension load of the liner 32 is supported by the tapered slips 52 along a plurality of slip cone surfaces 80 located around the mandrel 42. This arrangement helps to distribute the suspension load circumferentially through the cone sleeve 44 and the tapered slips 52 rather than radially into the mandrel 42.

[0070] The tapered slips 52, the retainer ring 54, and the cone sleeve 44 each include angular surfaces that help to hold the tapered slips 52 in position along the cone sleeve 44. The different angles may be positioned along the sides of the slip fingers 60 and the fixed ring fingers 58. The different angles on the fixed ring fingers 58 and the slip fingers 60 may extend outwardly from each other like a "V" and an inverted "V" to form mating V-angular surfaces.

[0071] Referring to Figure 4, a schematic view of the tapered slip 52 to facilitate the explanation of the features of the tapered slip 52, including the inclined surfaces that contribute to retention. The sliding fingers 60 create a space 82 therebetween to receive the corresponding fixed ring fingers 58. The sliding fingers 60 also include a second angled surface 84 that interlocks with a corresponding surface of the retaining ring 54. The second angled surface 84 can be located on the sides of each sliding finger 60 and can be oriented at different angles relative to a given reference plane. In the illustrated embodiment, the second angled surfaces 84 of each sliding finger 60 are inclined with respect to each other in a radially outward moving direction. Due to the different second angled surfaces 84, each sliding finger 60 effectively extends towards the thicker radially inward portion. The tapered slip 52 also includes a hammerhead 78 in the form of a hammerhead that flares towards the thicker radially inward portion. The hammerhead 78 is flared due to the inclined surfaces 86 located on both sides of the hammerhead structure.

[0072] Figure 5 is an example view of the retaining ring 54 to facilitate the explanation of the features of the retaining ring 54. The fixed ring fingers 58 extend axially from the base ring 87 and form a space 88 therebetween to receive the corresponding sliding fingers 60. The fixed ring fingers 58 also include a first angled surface 90 that interlocks with the corresponding second angled surface 84 of the tapered slip 52. The first angled surface 90 is located on both sides of each fixed ring finger 58. In the illustrated embodiment, the first angled surfaces 90 of each retaining fixed ring finger 58 are inclined with respect to each other in a radially inward moving direction. Due to the different first angled surfaces 90, each fixed ring finger 58 effectively extends into the thicker radially outward portion.

[0073] When the tapered slip 52 and the retaining ring 54 are assembled onto the mandrel 42, the angled surfaces 90 can be oriented substantially parallel to the corresponding second angled surfaces 84. Since the fixed ring fingers 58 extend towards the wider outer portion in the circumferential direction, the fixed ring fingers 58 are capable of locking the sliding fingers 60. Thus, the tapered slip 52 is limited in its radial movement.

[0074] A base edge is provided on the fixed finger ring 58. When the overlapping surface 64 abuts against the base edge 92, the sliding fingers 60 are prevented from further linearly / axially moving into the space 88 between the fixed ring fingers 58. By restricting this linear / axial movement of the tapered slip 52, the tapered slip 52 is prevented from moving to the decoupled position. At the same time, the interacting second angled surfaces 84, the inclined surfaces 86, and the first angled surfaces 90 prevent the radial movement of the tapered slip to prevent its release. Thus, the tapered slip 52 is fixed along the cone bushing 44, and the tapered slip 52 cannot be released until the hydraulic cylinder 62 is driven to force the tapered slip 52 to the set-down position.

[0075] The sliding finger 60 moves into the space 88 between the fixed-ring fingers 58 and then moves axially to interlock the second angular surface 84 of each slip 52 with the corresponding first angular surface 90 of the retaining ring 54, as Figure 7 shown. At this stage, the inclined surface 86 at the top of the slip 52, the third angular surface 96, the second angular surface 84 at the bottom of the slip 52, and the first angular surface 90 restrict the radially outward movement of the slip 52, thereby preventing its release. Additionally, the overlapping surface 64 of the hydraulic cylinder 62 can move towards the base edge 92 of the retaining ring 54 to prevent the slip 52 from linearly moving to the decoupled position. Thus, the interlocking angular surfaces and the engaging feature 64 ensure that the slips 52 are not inadvertently released from the liner hanger 34.

[0076] The cone sleeve 44, the slips 52, and the retaining ring 54 have relatively complex structures, including mating surfaces arranged at different angles and orientations. They can be cut by water jet or laser cutting processes to allow the shapes and surfaces of the corresponding components to be substantially the same.

[0077] A second embodiment of the present invention proposes a method for retaining the slips of a liner hanger, based on a system for retaining the slips of a liner hanger. The method includes:

[0078] Position and install a cone sleeve 44 with a tapered groove 50 on the mandrel 42 of the liner hanger;

[0079] Limit the hammer heads 78 at the upper ends 72 of each slip 52 within the corresponding tapered grooves 50 to form a sliding interlock through the angular surfaces of the annular grooves 50 and the angular surfaces of the hammer heads 78;

[0080] Fix the sliding fingers 60 at the lower ends 56 of each slip 52 through a retaining ring 54, and form an engaging interlock through the angular surfaces of the fixed-ring fingers 58 of the retaining ring 54 and the angular surfaces of the sliding fingers 60. The fixed-ring fingers 58 fix each slip 52 to prevent it from falling off the cone sleeve 44;

[0081] Further tighten the slips 52 through the hydraulic cylinder 64 of the hydraulic actuator 66 for setting the liner hanger, preventing excessive axial movement of the slips 52, and ensuring that the mating inclined surfaces of the slips 52 are held in place.

[0082] The terms "first", "second", etc. are used to distinguish similar objects and not to describe or indicate a specific order or sequence.

[0083] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those processes, methods, articles, or apparatus / devices.

[0084] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easily understood by those skilled in the art that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. A slip retaining system for a liner hanger, characterized in that, the system includes a mandrel (42), a cone sleeve (44), a tapered slip (52), a retaining ring (54) and a hydraulic actuator (66); one end of the mandrel (42) is connected to a running tool and is disposed in a wellbore (36), the other end of the mandrel (42) is bearing-connected to the cone sleeve (44), a tapered groove (50) is formed on the outer surface of the cone sleeve (44) along its axial direction, a plurality of groups of the tapered grooves (50) are circumferentially and uniformly distributed along the outer circumferential surface of the cone sleeve (44), a tapered slip (52) is slidably connected in the tapered groove (50), a plurality of teeth (70) are uniformly arranged on the outer surface of the tapered slip (52) along its length direction, and the teeth (70) are clamped and engaged with the inner surface of the casing (38) to achieve fixation; the retaining ring (54) has a fixed finger ring (58) with a plurality of sliding fingers (60) slidably engaging the tapered slip (52), preventing the tapered slip (52) from falling out of the retaining ring (54) during the setting of the liner hanger; a hydraulic setting mechanism (66) mounted around the mandrel (42) to selectively move the tapered slip (52) between a radially contracted position and a radially set position.

2. A slip retaining system for a liner hanger according to claim 1, characterized in that, the tapered slip (52) is slidably engaged with the retaining ring (54), and its specific structure is: sliding fingers (60) are arranged on the tapered slip (52), the sliding fingers (60) are slidably engaged with the fixed finger ring (58), the fixed finger ring (58) is arranged on the retaining ring (54), and the fixed finger ring (58) and the sliding fingers (60) are arranged in an interleaved manner.

3. A slip retaining system for a liner hanger according to claim 2, characterized in that, a hammer head (78) is arranged at the upper end (72) of the tapered slip (52) close to the mandrel (42), the hammer head (78) has an inclined surface (86) to slidably capture the hammer head (78) in a region on one side of the corresponding tapered groove (50) close to the mandrel (42), the hammer head (78) is defined to axially slide in the tapered groove (50), and the teeth (70) are arranged between the hammer head (78) and the sliding fingers (60).

4. A slip retaining system for a liner hanger according to claim 3, characterized in that, the processing methods of the tapered slip (52), the cone sleeve (44), the retaining ring (54) and the fixed finger ring (58) include at least one of water jet cutting or laser cutting.

5. A slip retaining system for a liner hanger according to claim 4, characterized in that, A fifth angular surface (76) is provided on the conical groove (50), and the fifth angular surface (76) cooperates with a fourth angular surface (74) which is provided on the conical slip (52). Through the mutually meshing surfaces of the fifth angular surface (76) and the fourth angular surface (74), the conical slip (52) is prevented from falling off when moving along the tapered sleeve (44).

6. A slip retaining system for a liner hanger according to claim 5, wherein, the hydraulic actuator (66) includes a hydraulic cylinder (62) which overlaps on the retaining ring (54); the hydraulic cylinder (62) is provided with an overlapping surface, and the overlapping surface (64) is in the form of an extended inner diameter of the hydraulic cylinder (62). The overlapping surface (64) can lap with the base edge (92) which is provided on the fixed finger ring (58) to prevent the plurality of conical slips (52) from falling off when axially moving during setting.

7. A slip retaining system for a liner hanger according to claim 6, wherein, each of the fixed finger rings (58) is gradually arranged to become narrower from wide in the direction from the conical slip (52) to the hydraulic cylinder (62); the axial lengths of every two adjacent fixed finger rings (58) are different, and the axial lengths of two fixed finger rings (58) at an interval of one fixed finger ring (58) distance are the same. Spaces (88) are provided between the plurality of fixed finger rings (58) and are arranged at different mating angles to insert and define the sliding fingers (60) of the conical slip (52).

8. A slip retaining system for a liner hanger according to claim 7, wherein, a first angular surface (90) is provided on the fixed finger ring (58) in the circumferential direction, and the first angular surface (90) is interlocked with a second angular surface (84) which is provided on the sliding finger (60).

9. A slip retaining system for a liner hanger according to claim 8, wherein, the tapered sleeve (44) is configured to be able to install a plurality of conical slips (52) from the outside of the tapered sleeve (44).

10. A method for retaining slips of a liner hanger, based on a slip retaining system for a liner hanger according to any one of claims 1-9, wherein the method includes: positioning and installing a tapered sleeve (44) with a conical groove (50) on the mandrel (42) of the liner hanger; limiting the hammer head (78) at the upper end (72) of each conical slip (52) in the corresponding conical groove (50), and forming a sliding interlock through the angular surface of the annular groove (50) and the angular surface of the hammer head (78). By maintaining the retaining ring (54) to fix the sliding fingers (60) at the lower end (56) of each tapered slip (52), the angular surfaces of the retaining fingers (58) of the retaining ring (54) form an engaging interlock with the angular surfaces of the sliding fingers (60), and the retaining fingers (58) fix each tapered slip (52) to prevent it from falling off the cone bushing (44); Through the hydraulic cylinder (64) of the hydraulic actuator (66) for setting the liner hanger, the tapered slips (52) are further tightened to prevent excessive axial movement of the tapered slips (52) and ensure that the tapered slips (52) are held in place on the mating inclined surfaces.

Images