Soluble bridge plug

Abstract

The invention relates to the technical field of bridge plugs, in particular to a soluble bridge plug. The soluble bridge plug comprises a pull rod, a ball seat, a rubber sleeve, a cone assembly, two slips and a lower connector, the pull rod is in threaded connection with the lower connector, a ball socket capable of containing the fracturing ball is formed in the top end of the ball seat, and the rubber sleeve is arranged on the periphery of the ball seat in a sleeving mode. The slip is provided with a plurality of slip teeth arranged in the circumferential direction, and a slip groove is formed between every two adjacent slip teeth. The two slips are oppositely arranged, the slip teeth of one slip are right opposite to the slip grooves of the other slip, and the inner hole of one slip is connected to the conical surface of the periphery of the cone assembly in a sleeved mode. When the rubber sleeve is pressed, the rubber sleeve expands in the radial direction and is tightly attached to the inner wall of the casing pipe, the slips are fractured at the positions of the slip grooves and are separated into a plurality of independent slip teeth, the slip teeth of the two slips move from bottom to top along the conical surface of the cone assembly and are inserted and matched in a staggered mode to form a closed ring body, and the closed ring body can be tightly attached to the inner wall of the casing pipe and support the expanded rubber sleeve. The soluble bridge plug improves the expansion ratio, the compression strength and the sealing performance.

Description

Technical Field

[0001] The invention relates to the technical field of bridge plugs, and in particular to a soluble bridge plug. Background Art

[0002] At present, the staged fracturing technology for oil wells or shale gas wells mainly adopts the pumping soluble bridge plug perforation combined staged fracturing process, which mainly divides the horizontal well into several sections through the soluble bridge plug, and the soluble bridge plug is transported to the target well section by hydraulic pumping to achieve the purpose of soluble bridge plug setting and isolation.

[0003] In the development of oil and gas, casing deformation in oil wells or gas wells is prone to occur during fracturing construction, which makes it impossible to install conventional soluble bridge plugs. The existing practice is to use a perforating gun to perforate all the casing below the deformation point in the well, and then use a temporary plugging construction method to perform general fracturing. The effectiveness and pertinence of the construction cannot be guaranteed, and a certain layer in the well cannot be accurately constructed. The existing soluble bridge plugs also have problems such as small expansion ratio, poor compressive strength and stability, which makes the fracturing transformation effect not guaranteed. Summary of the invention

[0004] The object of the present invention is to provide a soluble bridge plug to improve the expansion ratio, pressure resistance and sealing performance of the soluble bridge plug.

[0005] To achieve this purpose, the technical solution adopted by the present invention is:

[0006] A soluble bridge plug comprises a tie rod, a ball seat, a rubber sleeve, a cone assembly, two slips and a lower joint, wherein the tie rod is sleeved with the ball seat, the cone assembly, the two slips and the lower joint in sequence from top to bottom along the axial direction, and the tie rod is threadedly connected with the lower joint, a ball socket capable of accommodating a fracturing ball is provided at the top of the ball seat, and the rubber sleeve is sleeved on the outer periphery of the ball seat;

[0007] The slip has a plurality of slip teeth arranged circumferentially, and a slip groove is formed between two adjacent slip teeth; the two slips are arranged opposite to each other, and the slip teeth of one slip are directly opposite to the slip groove of the other slip, and the inner hole of one slip is sleeved on the conical surface of the outer periphery of the cone assembly;

[0008] The rubber cylinder expands radially and fits tightly against the inner wall of the casing when under pressure, and the slips break at the slip groove and separate into a plurality of independent slip teeth. The slip teeth of two slips move from bottom to top along the conical surface of the cone assembly and are staggered and plugged into each other to form a closed ring body. The closed ring body can fit tightly against the inner wall of the casing and support the expanded rubber cylinder.

[0009] As a preferred solution for the soluble bridge plug, the conical surface of the cone assembly is arranged to be inclined downward and inward from top to bottom; and the slip tooth has a guiding inclined surface that can fit with the conical surface.

[0010] As a preferred solution of the soluble bridge plug, a slip tooth is embedded on the outer side of the slip tooth, and the hardness of the slip tooth is higher than the hardness of the slip tooth.

[0011] As a preferred solution for the soluble bridge plug, the slip groove is a V-shaped groove, and a weak area is formed at the groove tip of the V-shaped groove. The slip can be broken at the weak area to separate and form a plurality of independent slip teeth.

[0012] As a preferred solution for the soluble bridge plug, a first hoop groove is circumferentially arranged at the end of the cava near the weak zone, a mounting groove is arranged on the outer side of the cava tooth, and the mounting grooves of the multiple cava teeth of the two cava together form a second hoop groove, and clamps are both provided in the first hoop groove and the second hoop groove.

[0013] As a preferred solution for the soluble bridge plug, the two cava are an upper cava and a lower cava which are arranged opposite to each other up and down, the inner hole of the upper cava is sleeved on the conical surface, the lower cava is provided with a limiting block near the bottom surface of the lower joint, the top surface of the lower joint is provided with a limiting groove, and the limiting block is clamped in the limiting groove.

[0014] As a preferred solution for the soluble bridge plug, a plurality of limit blocks are arranged at circumferential intervals on the bottom surface of the lower cava, a limit ring is arranged on the top surface of the lower joint, a plurality of baffles are arranged at circumferential intervals on the limit ring, and two adjacent baffles and at least part of the limit ring form a limit groove.

[0015] As a preferred solution of the soluble bridge plug, the hardness of the end of the rubber tube close to the ball socket is smaller than the hardness of the end of the rubber tube close to the cone assembly.

[0016] As a preferred solution for the soluble bridge plug, the hardness of the end of the rubber tube close to the ball socket is 85HR-90HR, and the hardness of the end of the rubber tube close to the cone assembly is 90HR-95HR.

[0017] As a preferred solution of the soluble bridge plug, the soluble bridge plug further comprises a back ring, a mounting ring is convexly provided on the top of the cone assembly, and the back ring is sleeved on the mounting ring and abuts against the top of the cone assembly;

[0018] The back ring is arranged to tilt outward from bottom to top, and the back ring, the top end of the mounting ring and at least a part of the outer peripheral surface of the cone assembly form an annular groove, and the rubber cylinder is located in the annular groove.

[0019] As a preferred solution of the soluble bridge plug, the back ring includes a first ring body and a second ring body, the first ring body is stacked on top of the second ring body, and the outer diameter of the first ring body when unfolded in a plane is larger than the outer diameter of the second ring body when unfolded in a plane.

[0020] As a preferred solution for the soluble bridge plug, the outer peripheral surface of the cone assembly has a step structure, and the back ring, the top end of the mounting ring and the step structure form the annular groove; the outer edge of the step surface of the step structure has a rib.

[0021] As a preferred solution of the soluble bridge plug, the cone assembly comprises:

[0022] A main cone, the outer periphery of which has the conical surface;

[0023] The check ring is an unclosed circular ring, which is sleeved in the inner hole of the main cone; the ball seat can squeeze the rubber cylinder to expand radially under the thrust of the sealing tool, and the lower end of the ball seat extends into the inner hole of the main cone and is connected to the check ring.

[0024] As a preferred solution for the soluble bridge plug, the inner hole of the stop ring is axially provided with multiple first clamping parts, and the lower end of the ball seat is axially provided with multiple second clamping parts, and at least some of the first clamping parts can be clamped and matched with at least some of the second clamping parts in a one-to-one correspondence.

[0025] The beneficial effects of the present invention are:

[0026] A soluble bridge plug proposed by the present invention includes a pull rod, a ball seat, a rubber cylinder, a cone assembly, two slips and a lower joint. The pull rod is sequentially sleeved with the ball seat, the cone assembly, the two slips and the lower joint along the axial direction from top to bottom, and the pull rod is threadedly connected to the lower joint. The top of the ball seat is provided with a ball socket capable of accommodating a fracturing ball, and the rubber cylinder is sleeved on the outer periphery of the ball seat. By arranging the two slips opposite to each other and the slip teeth of one slip facing the slip groove of the other slip, when the rubber cylinder is compressed, it radially expands and clings to the inner wall of the casing, the slips break at the slip groove and separate into a plurality of independent slip teeth, the slip teeth of the two slips move from bottom to top along the conical surface of the cone assembly and are staggered and plugged to form a closed ring body, which can cling to the inner wall of the casing and support the expanded rubber cylinder. After the two slips are broken and separated, a seamless closed ring body is formed, which further improves the pressure resistance and sealing of the soluble bridge plug. At the same time, the closed ring body can provide support for the deformed rubber sleeve, so that the rubber sleeve can undergo a large radial expansion deformation, thereby improving the expansion ratio of the soluble bridge plug, thereby being suitable for fracturing construction of casing-changing wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a half-section diagram of the assembly structure of the soluble bridge plug and the matching components provided by the embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of a partial structure of a soluble bridge plug after setting provided by an embodiment of the present invention;

[0029] Figure 3 is a schematic structural diagram of an upper slip provided in an embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of the assembly structure of two slips provided in an embodiment of the present invention;

[0031] Figure 5 It is a schematic structural diagram of a lower joint provided in an embodiment of the present invention.

[0032] The names and numbers of the components in the figure are as follows:

[0033] 100, casing; 10, push tube; 20, setting tool joint; 30, limit gland;

[0034] 1. Pull rod; 2. Ball seat; 21. Ball socket; 22. First step surface; 23. Second step surface; 24. Step surface; 25. Retaining edge; 26. Second clamping part; 3. Rubber cylinder; 4. Cone assembly; 41. Main cone; 411. Cone surface; 412. Mounting ring; 42. Stop ring; 5. Slip; 510. Upper slip; 520. Lower slip; 51. Slip tooth; 52. Slip groove; 53. Slip tooth; 54. Guide slope; 55. First hoop groove; 56. Second hoop groove; 57. Limit block; 6. Lower joint; 610. Limit groove; 61. Limit ring; 62. Baffle; 63. Groove; 7. Back ring; 71. First ring body; 72. Second ring body. DETAILED DESCRIPTION

[0035] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and through specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, not all.

[0036] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0038] In the description of this embodiment, the terms "upper", "lower", "right", "left" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0039] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0040] At present, the staged fracturing technology for oil wells or shale gas wells mainly adopts the pumping soluble bridge plug perforation combined staged fracturing process, which mainly divides the horizontal well into several sections by using the soluble bridge plug, and the soluble bridge plug is transported to the target well section by hydraulic pumping to complete the purpose of soluble bridge plug setting and isolation. In the development of oil and natural gas, casing deformation in oil wells or gas wells is prone to occur during the fracturing construction process, resulting in the inability to lower conventional soluble bridge plugs. The existing practice is to use a perforating gun to shoot all the casing below the casing change point in the well, and then use a temporary plugging construction method to perform general fracturing. The effectiveness and pertinence of the construction cannot be guaranteed, and a certain layer section in the well cannot be accurately constructed. The existing soluble bridge plugs also have the problems of small expansion ratio, poor compressive strength and stability, which makes the fracturing transformation effect cannot be guaranteed.

[0041] To solve the above problems, Figure 1 and Figure 2As shown, this embodiment proposes a soluble bridge plug, which includes a tie rod 1, a ball seat 2, a rubber cylinder 3, a cone assembly 4, two slips 5 and a lower joint 6. The tie rod 1 is sleeved with the ball seat 2, the cone assembly 4, the two slips 5 and the lower joint 6 in sequence from top to bottom along the axial direction, and the tie rod 1 is threadedly connected with the lower joint 6. The top of the ball seat 2 is provided with a ball socket 21 capable of accommodating a fracturing ball, and the rubber cylinder 3 is sleeved on the outer periphery of the ball seat 2. The slip 5 has a plurality of slip teeth 51 arranged circumferentially, and a slip groove 52 is formed between two adjacent slip teeth 51. The two slips 5 are arranged opposite to each other, and the slip teeth 51 of one slip 5 are directly opposite to the slip groove 52 of the other slip 5, and the inner hole of one slip 5 is sleeved on the conical surface 411 of the outer periphery of the cone assembly 4. When under pressure, the rubber cylinder 3 expands radially and fits tightly against the inner wall of the casing 100, and the slips 5 break at the slip groove 52 and separate into multiple independent slip teeth 51. The slip teeth 51 of the two slips 5 move from bottom to top along the conical surface 411 of the cone assembly 4 and are staggered and plugged into each other to form a closed ring body. The closed ring body can fit tightly against the inner wall of the casing 100 and support the expanded rubber cylinder 3.

[0042] When a casing-deformed well (i.e., an oil or gas well with a deformed casing 100) is subjected to staged fracturing, Figure 1 As shown, the supporting parts of the soluble bridge plug include a push tube 10, a setting tool joint 20 and a limit gland 30. The top of the ball seat 2 has a two-step structure and gradually decreases from bottom to top. The two-step structure includes a first step surface 22 and a second step surface 23, and the height of the first step surface 22 is lower than the height of the second step surface 23. The bottom end of the push tube 10 is sleeved on the top of the ball seat 2 and pressed against the first step surface 22. The top of the push tube 10 can be threadedly connected with the setting tool. The setting tool joint 20 is threadedly connected with the top of the pull rod 1. The limit gland 30 is a transparent cover structure. The limit gland 30 is sleeved and threadedly connected to the pull rod 1, and the edge of the limit gland 30 presses against the second step surface 23. The push tube 10 and the setting tool joint 20 jointly apply a driving force to the soluble bridge plug, so that the soluble bridge plug can be moved to a predetermined setting position after passing through the casing change point along the casing 100 of the casing change well. When the soluble bridge plug reaches the predetermined sealing position in the casing 100, the sealing tool applies a thrust (i.e., sealing force) to the ball seat 2, so that the ball seat 2 moves downward (in the direction indicated by the arrow in the figure) to squeeze the rubber sleeve 3 to deform. The rubber sleeve 3 expands and deforms radially after being compressed. At the same time, the thrust of the sealing tool is transmitted to the two slips 5 through the rubber sleeve 3 and the cone assembly 4, so that the two slips 5 are broken respectively to form a plurality of independent slip teeth 51.

[0043] In this embodiment, the two slips 5 are arranged opposite to each other and the slip teeth 51 of one slip 5 are aligned with the slip grooves 52 of the other slip 5, so that the two slips 5 are broken and separated to form a seamless closed ring body, which further improves the compressive strength and sealing performance of the soluble bridge plug. At the same time, the closed ring body can provide support for the deformed rubber sleeve 3, so that the rubber sleeve 3 can undergo a large radial expansion deformation, thereby improving the expansion ratio of the soluble bridge plug, so that it is suitable for the fracturing construction of the casing change well, so as to meet the needs of staged fracturing construction when the casing 100 is greatly deformed.

[0044] The soluble bridge plug of this embodiment is a small-sized bridge plug and has an expansion ratio greater than 30%. For example, when the initial inner diameter of the casing 100 of the oil well or gas well is 114.3 mm, and the inner diameter of the casing 100 at the casing change point after deformation is less than 85 mm, the soluble bridge plug of this embodiment can provide effective plugging for the staged fracturing construction of the above casing change well, achieve good mechanical isolation, and ensure good fracturing effect.

[0045] It should be noted that the push tube 10, the setting tool joint 20, the pull rod 1 and the limit gland 30 are all made of steel, the rubber tube 3 is made of water-soluble rubber, and the remaining components of the soluble bridge plug are made of soluble metal materials. The rubber tube 3 can be dissolved in an aqueous solution at a certain temperature. Since the rubber tube 3 is a mature component of the soluble bridge plug, it will not be described here.

[0046] In this embodiment, the hardness of the end of the rubber cylinder 3 close to the ball socket 21 is less than the hardness of the end of the rubber cylinder 3 close to the cone assembly 4, so that the rubber cylinder 3 is a variable hardness rubber cylinder 3, and the hardness of the upper end of the rubber cylinder 3 (the end close to the ball socket 21) is relatively small, so that the rubber cylinder 3 can start to expand and deform radially by providing a small sealing force by the setting tool, so as to meet the setting stroke of the rubber cylinder 3 within the safety range. The hardness of the lower end of the rubber cylinder 3 (the end close to the cone assembly 4) is relatively large, so that the lower end of the rubber cylinder 3 has good structural strength and support effect, improves the stability of the rubber cylinder 3 after radial expansion and deformation, and ensures the sealing between the deformed rubber cylinder 3 and the inner wall of the sleeve 100.

[0047] Specifically, the hardness of the end of the rubber tube 3 close to the ball socket 21 is 85HR-90HR, and the hardness of the end of the rubber tube 3 close to the cone assembly 4 is 90HR-95HR. In other embodiments, the hardness of the upper and lower ends of the rubber tube 3 can also be flexibly selected from materials of different hardnesses according to needs, which is not specifically limited here.

[0048] like Figure 1 and Figure 2As shown, the soluble bridge plug also includes a back ring 7, and a mounting ring 412 is convexly provided on the top of the cone assembly 4. The back ring 7 is sleeved on the mounting ring 412 and abuts against the top of the cone assembly 4. The back ring 7 is arranged obliquely and outwardly from bottom to top, and the back ring 7, the top of the mounting ring 412 and at least part of the outer peripheral surface of the cone assembly 4 form an annular groove, and the rubber cylinder 3 is located in the annular groove. Specifically, the outer peripheral surface of the cone assembly 4 has a step structure, and the back ring 7, the top of the mounting ring 412 and the step structure form an annular groove. The annular groove can limit the rubber cylinder 3 in the up and down directions, so that when the sealing force of the sealing tool is transmitted to the rubber cylinder 3 through the ball seat 2, the rubber cylinder 3 only expands and deforms in the radial direction.

[0049] Furthermore, the outer edge of the step surface 24 of the step structure has a rib 25. The rib 25 can limit the upper end of the rubber tube 3 to prevent the upper end of the rubber tube 3 from coming out of the annular groove during radial expansion and deformation. The back ring 7 can support and limit the rubber tube 3 to prevent the lower end of the rubber tube 3 from coming out of the annular groove during radial expansion and deformation. The rib 25 and the back ring 7 realize axial limitation of the upper and lower ends of the rubber tube 3, ensuring the stability and reliability of the rubber tube 3 during radial expansion and deformation.

[0050] like Figure 2 As shown, the back ring 7 can provide initial support for the rubber cylinder 3 that has not undergone radial expansion and deformation. When the back ring 7 is affected by the radial expansion and deformation of the rubber cylinder 3, the back ring 7 can be expanded radially to be in a planar state, so that the back ring 7 is tightly attached to the closed ring body formed by the staggered insertion of the two slips 5, that is, the back ring 7 and the closed ring body can provide dual support for the rubber cylinder 3 that has undergone radial expansion and deformation, thereby improving the expansion ratio of the rubber cylinder 3 and the sealing effect after radial expansion and deformation. During the sealing process, when the squeezing force of the rubber cylinder 3 on the back ring 7 is large, the back ring 7 can continue to bend and deform in the opposite direction on the basis of radial expansion and press against the end face of the closed ring body, and part of the rubber cylinder 3 also presses against the end face of the closed ring body.

[0051] like Figure 1 and Figure 2 As shown, the back ring 7 includes a first ring body 71 and a second ring body 72. The first ring body 71 is stacked on the second ring body 72, and the outer diameter of the first ring body 71 when expanded in a plane is larger than the outer diameter of the second ring body 72 when expanded in a plane. The back ring 7 is arranged as a split assembly structure, which is convenient for processing and assembling the back ring 7. At the same time, the outer diameter of the first ring body 71 when expanded in a plane is relatively large, which is convenient for better limiting the rubber cylinder 3, and the second ring body 72 can provide better support.

[0052] like Figure 1 and Figure 2As shown, the cone assembly 4 includes a main cone 41 and a check ring 42, and the outer periphery of the main cone 41 has a cone surface 411. The check ring 42 is an unclosed circular ring, and the check ring 42 is sleeved in the inner hole of the main cone 41. When the ball seat 2 squeezes the rubber cylinder 3 to expand and deform radially, the lower end of the ball seat 2 extends into the inner hole of the main cone 41 and is connected to the check ring 42. As the rubber cylinder 3 expands and deforms radially, the ball seat 2 moves from top to bottom to the inner hole of the main cone 41 to connect with the check ring 42, thereby locking the ball seat 2 on the main cone 41 to prevent the rubber cylinder 3 from being unsealed due to its own elastic force after setting, so as to ensure the stability of the radial expansion and deformation of the rubber cylinder 3.

[0053] Specifically, the inner hole of the stop ring 42 is axially provided with a plurality of first clamping parts, and the lower end of the ball seat 2 is axially provided with a plurality of second clamping parts 26, and at least some of the first clamping parts can be clamped and matched with at least some of the second clamping parts 26 in a one-to-one correspondence. The first clamping part and the second clamping part 26 are both annular teeth, and the tooth tips of the first clamping part and the second clamping part 26 face opposite directions, so that the first clamping part and the second clamping part 26 are clamped and matched, and the ball seat 2 is reliably connected to the stop ring 42. In other embodiments, the first clamping part and the second clamping part 26 can also be other matching structures, as long as they can ensure the reliable connection between the ball seat 2 and the stop ring 42.

[0054] like Figure 2 and Figure 3 As shown, the two slips 5 are respectively an upper slip 510 and a lower slip 520 which are arranged opposite to each other up and down, and the inner hole of the upper slip 510 is sleeved on the conical surface 411. The conical surface 411 of the cone assembly 4 is arranged to be inclined inward from top to bottom. The slip teeth 51 have a guiding inclined surface 54 which can fit with the conical surface 411. When the rubber cylinder 3 undergoes radial expansion and deformation, the two slips 5 are broken at the slip groove 52 and separated into a plurality of independent slip teeth 51, and the guiding inclined surface 54 of the slip teeth 51 fits with the conical surface 411 and moves from bottom to top along the conical surface 411 until the slip teeth 51 of the two slips 5 are staggered and plugged together to form a closed ring body.

[0055] Specifically, the slip groove 52 is a V-shaped groove, and a weak area is formed at the groove tip of the V-shaped groove. The slip 5 can be broken at the weak area to separate and form a plurality of independent slip teeth 51. The depth of the V-shaped groove is slightly smaller than the axial length of the slip 5, so that the solid part of the slip 5 at the groove tip is smaller, and the groove tip of the V-shaped groove is a stress concentration point. When the extrusion force generated by the deformation of the rubber cylinder 3 is transmitted to a slip 5 (upper slip 510) close to the main cone 41 through the main cone 41, the slip 5 breaks at the groove tip of each V-shaped groove to form a plurality of independent slip teeth 51. As the two slips 5 crawl from bottom to top along the conical surface 411 of the main cone 41, the slip teeth 51 of the upper slip 510 are first broken and separated, and the ends of the slip teeth 51 of the upper slip 510 are staggered and inserted into the corresponding slip grooves 52 of the lower slip 520. Under the extrusion of the slip teeth 51 of the upper slip 510, the lower slip 520 can be broken and separated in its own slip groove 52 to form an independent slip tooth 51. Subsequently, the slip teeth 51 of the upper slip 510 and the slip teeth 51 of the lower slip 520 both move from bottom to top along the conical surface 411. When the slip teeth 51 of the upper slip 510 move into place, the slip teeth 51 of the lower slip 520 continue to move from bottom to top for a distance until the slip teeth 51 of the two slips 5 are staggered and inserted to form a closed loop.

[0056] Furthermore, if Figure 3 and Figure 4 As shown, a slip tooth 53 is embedded on the outer side of the slip tooth 51, and the hardness of the slip tooth 53 is higher than the hardness of the slip tooth 51. By providing the slip tooth 53 with higher hardness, the closed loop body is firmly anchored on the inner wall of the casing 100 through the slip tooth 53, thereby improving the setting stability of the soluble bridge plug.

[0057] It should be noted that the two circumferential oblique side surfaces of the slip teeth 51 are respectively an oblique side surface of the two slip grooves 52 on the left and right sides of the slip teeth 51, so that the upper slip 510 and the lower slip 520 can achieve a tight staggered plug-in fit, ensuring that there is no gap between the slip teeth 51 in the closed loop body, thereby improving the sealing effect. When the upper slip 510 and the lower slip 520 are installed on the pull rod 1, part of the end of the slip teeth 51 of the upper slip 510 extends into the slip groove 52 of the lower slip 520, and part of the end of the slip teeth 51 of the lower slip 520 can extend into the slip groove 52 of the upper slip 510, and each slip tooth 51 is fitted with the oblique side surface of the corresponding slip groove 52 one by one, so that the mutual circumferential limitation of the upper slip 510 and the lower slip 520 is achieved.

[0058] Furthermore, if Figure 3 and Figure 4As shown, the end of the slip 5 near the weak zone is circumferentially provided with a first hoop groove 55, the outer side of the slip tooth 51 is provided with a mounting groove, and the mounting grooves of the multiple slip teeth 51 of the two slips 5 together form a second hoop groove 56, and clamps are sleeved in the first hoop groove 55 and the second hoop groove 56. By sleeved the two clamps in the first hoop groove 55 and the second hoop groove 56 respectively, the stability of the two slips 5 is further improved, and the two slips 5 are prevented from accidentally falling apart during the lowering construction.

[0059] like Figure 1 , Figure 4 and Figure 5 As shown, a limit block 57 is provided on the bottom surface of the lower slip 520 near the lower joint 6, and a limit groove 610 is provided on the top surface of the lower joint 6, and the limit block 57 is engaged in the limit groove 610. Through the engagement of the limit block 57 and the limit groove 610, the lower joint 6 can limit the slip 5 in the circumferential direction to prevent the slip 5 from rotating around the tie rod 1. Of course, the slip 5, the main cone 41 and the ball seat 2 can be connected to the tie rod 1 by fasteners such as pins, and the strength of the pins is relatively small and will not affect the normal use of the soluble bridge plug.

[0060] Specifically, a plurality of limiting blocks 57 are arranged at intervals along the circumferential direction on the bottom surface of the lower slip 520, a limiting ring 61 is arranged at the top surface of the lower joint 6, a plurality of baffles 62 are arranged at intervals along the circumferential direction on the limiting ring 61, and two adjacent baffles 62 and at least part of the limiting ring 61 surround a limiting groove 610. By increasing the number of limiting blocks 57 and limiting grooves 610, the axial limiting effect of the lower joint 6 on the slip 5 is further improved, and the stability of the soluble bridge plug is improved.

[0061] It should be noted that if Figure 5 As shown, the bottom end of the lower joint 6 is provided with four grooves 63, which form a cross shape and are connected to the inner hole of the lower joint 6, so as to ensure that when the fracturing ball is pressed against the lower end of the lower joint 6, the inner hole of the lower joint 6 is connected to the casing 100, which is convenient for the return channel after fracturing construction. As the sealing force applied by the sealing tool gradually increases, the threaded connection between the pull rod 1 and the lower joint 6 is sheared off, and the sealing tool pulls the pull rod 1 out of the lower joint 6, that is, lifts the pipe string, and finally the soluble bridge plug is set and released, and the ball (fracking ball) can be dropped to carry out fracturing construction.

[0062] The above embodiments are only to illustrate the basic principles and characteristics of the present invention. The present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and modifications, which are within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A soluble bridge plug, It is characterized in that The invention comprises a pull rod (1), a ball seat (2), a rubber cylinder (3), a cone assembly (4), two slips (5) and a lower joint (6); the pull rod (1) is sleeved with the ball seat (2), the cone assembly (4), the two slips (5) and the lower joint (6) in sequence from top to bottom along the axial direction, and the pull rod (1) is threadedly connected to the lower joint (6); a ball socket (21) capable of accommodating a fracturing ball is provided at the top of the ball seat (2), and the rubber cylinder (3) is sleeved on the outer periphery of the ball seat (2); The slip (5) has a plurality of slip teeth (51) arranged circumferentially, and a slip groove (52) is formed between two adjacent slip teeth (51); the two slips (5) are arranged opposite to each other, and the slip teeth (51) of one slip (5) are directly opposite to the slip groove (52) of the other slip (5); the inner hole of one slip (5) is sleeved on the conical surface (411) on the outer periphery of the cone assembly (4); The rubber cylinder (3) expands radially when under pressure and fits tightly against the inner wall of the sleeve (100), and the slips (5) break at the slip groove (52) and separate into a plurality of independent slip teeth (51), and the slip teeth (51) of the two slips (5) move from bottom to top along the conical surface (411) of the cone assembly (4) and are staggered and plugged into each other to form a closed ring body, and the closed ring body can fit tightly against the inner wall of the sleeve (100) and support the expanded rubber cylinder (3).

2. The soluble bridge plug according to claim 1, It is characterized in that The conical surface (411) of the cone assembly (4) is arranged to be inclined downward and inward from top to bottom; and the slip tooth (51) has a guiding inclined surface (54) capable of fitting with the conical surface (411).

3. The soluble bridge plug according to claim 1, It is characterized in that A slip tooth (53) is embedded on the outer side surface of the slip tooth (51), and the hardness of the slip tooth (53) is higher than the hardness of the slip tooth (51).

4. The soluble bridge plug according to claim 1, It is characterized in that The slip groove (52) is a V-shaped groove, and a weak area is formed at the groove tip of the V-shaped groove. The slip (5) can be broken at the weak area to separate and form a plurality of independent slip teeth (51).

5. The soluble bridge plug according to claim 4, It is characterized in that The end of the slip (5) close to the weak zone is circumferentially provided with a first hoop groove (55), the outer side surface of the slip tooth (51) is provided with a mounting groove, and the mounting grooves of the multiple slip teeth (51) of the two slips (5) together form a second hoop groove (56), and the first hoop groove (55) and the second hoop groove (56) are both sleeved with a clamp.

6. The soluble bridge plug according to claim 1, It is characterized in that The two slips (5) are respectively an upper slip (510) and a lower slip (520) which are arranged opposite to each other in the upper and lower directions. The inner hole of the upper slip (510) is sleeved on the conical surface (411). A limiting block (57) is arranged on the bottom surface of the lower slip (520) close to the lower joint (6). A limiting groove (610) is arranged on the top surface of the lower joint (6). The limiting block (57) is clamped in the limiting groove (610).

7. The soluble bridge plug according to claim 6, It is characterized in that The bottom surface of the lower cava (520) is provided with a plurality of limit blocks (57) at intervals along the circumferential direction, the top surface of the lower joint (6) is provided with a limit ring (61), a plurality of baffles (62) are provided on the limit ring (61) at intervals along the circumferential direction, and two adjacent baffles (62) and at least a portion of the limit ring (61) are arranged to form a limit groove (610).

8. The soluble bridge plug according to claim 1, It is characterized in that The hardness of the end of the rubber cylinder (3) close to the ball socket (21) is smaller than the hardness of the end of the rubber cylinder (3) close to the cone assembly (4).

9. The soluble bridge plug according to claim 8, It is characterized in that The hardness of the end of the rubber cylinder (3) close to the ball socket (21) is 85HR-90HR, and the hardness of the end of the rubber cylinder (3) close to the cone assembly (4) is 90HR-95HR.

10. The soluble bridge plug according to claim 1, It is characterized in that The soluble bridge plug further comprises a back ring (7), a mounting ring (412) is convexly provided on the top end of the cone assembly (4), and the back ring (7) is sleeved on the mounting ring (412) and abuts against the top end of the cone assembly (4); The back ring (7) is arranged to tilt upward and outward from bottom to top, and the top of the back ring (7), the mounting ring (412) and at least part of the outer peripheral surface of the cone assembly (4) form an annular groove, and the rubber cylinder (3) is located in the annular groove.

11. The soluble bridge plug according to claim 10, It is characterized in that The back ring (7) comprises a first ring body (71) and a second ring body (72), wherein the first ring body (71) is stacked on top of the second ring body (72), and the outer diameter of the first ring body (71) when unfolded in a plane is larger than the outer diameter of the second ring body (72) when unfolded in a plane.

12. The soluble bridge plug according to claim 10, It is characterized in that The outer peripheral surface of the cone assembly (4) has a step structure, and the back ring (7), the top end of the mounting ring (412) and the step structure form the annular groove; the outer edge of the step surface (24) of the step structure has a retaining edge (25).

13. The soluble bridge plug according to claim 1, It is characterized in that The cone assembly (4) comprises: A main cone (41), the outer periphery of the main cone (41) having the cone surface (411); The stop ring (42) is an unclosed circular ring, and the stop ring (42) is sleeved in the inner hole of the main cone (41); the ball seat (2) is able to squeeze the rubber cylinder (3) to expand radially under the thrust of the sealing tool, and the lower end of the ball seat (2) extends into the inner hole of the main cone (41) and is connected to the stop ring (42).

14. The soluble bridge plug according to claim 13, It is characterized in that The inner hole of the stop ring (42) is axially provided with a plurality of first clamping parts, and the lower end of the ball seat (2) is axially provided with a plurality of second clamping parts (26), and at least some of the first clamping parts can be clamped and matched with at least some of the second clamping parts (26) in a one-to-one correspondence.

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