Soluble bridge plug for casing well

Abstract

This invention relates to a soluble bridge plug for casing-modified wells. The soluble bridge plug includes a soluble ball, a release ring, a central tube, slips, a rubber sleeve, and a guide shoe. The setting sleeve pushes the slips, guide block, slips, cone, extension body, secondary cone, rubber sleeve, and back ring downwards. The extension body expands radially under force, and the rubber sleeve and back ring expand radially as they descend, sealing the annulus between the central tube and the casing. When the starting force of the slips ring is reached, the slips expand radially. When the slips move to the outer diameter of the cone, they continue to move radially through the expanded outer cone surface of the extension until they bite into the inner wall of the casing, forming a self-locking mechanism. When the force generated by the setting tool reaches the thread breaking force of the release ring, the setting tool disengages from the bridge plug, completing the setting process. When fracturing of the producing layer above the bridge plug is required, the soluble ball is placed into the cone hole of the central tube, sealed, and then fracturing is performed. After fracturing, the soluble ball will dissolve under certain conditions, forming a full-bore channel inside the casing.

Description

Technical Field

[0001] This invention relates to a downhole tool for oil development, and more particularly to a soluble bridge plug for casing wells. Background Technology

[0002] Currently, due to the deep burial, complex structure, and variable pressure system of deep shale gas reservoirs, poor reservoir compressibility, difficulty in volumetric stimulation, and high overall casing deformation rate, problems such as reduced construction efficiency, lost sections, and insufficient large-section pressure stimulation are prominent. Furthermore, existing soluble bridge plugs often encounter obstruction and set midway in casing wells due to their small setting range. Summary of the Invention

[0003] To address the above problems, this invention provides a soluble bridge plug for casing wells. Under certain temperature and salinity conditions, the bridge plug can be completely dissolved, eliminating the need for continuous tubing drilling and thus meeting the development needs of deep shale gas casing wells.

[0004] The technical solution adopted in this invention is: a soluble bridge plug for variable wells, characterized in that: it includes a soluble ball, a release ring, a central tube, a slip ring, a rubber sleeve, and a guide shoe; the upper end of the inner hole of the central tube opens outward to form a conical hole for placing the soluble ball; the release ring is fixedly disposed on the outer circular surface of the upper end of the central tube, and the guide shoe is fixedly disposed on the outer circular surface of the lower end of the central tube; between the release ring and the rubber sleeve, a slip ring, an upper guide block, an upper slip, an upper cone, an upper extension, an upper secondary cone, and an upper back ring are sequentially disposed on the outer circular surface of the central tube; between the guide shoe and the rubber sleeve, a lower guide block, a lower slip, a lower cone, a lower extension, an lower secondary cone, and a lower back ring are sequentially disposed on the outer circular surface of the central tube.

[0005] Preferably, the outer surface of the locking ring is flush with the outer surface of the release ring and is fixedly connected to the central tube by a shear pin; the locking ring is provided with a locking ring groove that mates with the upper guide block; the guide shoe is provided with a guide shoe groove that mates with the lower guide block.

[0006] Preferably, the upper guide block and the lower guide block have the same structure, each including a large end and a small end. The large end of the upper guide block mates with the groove of the retaining ring, and the small end of the upper guide block mates with the concave hole on the upper end face of the upper retaining ring. The large end of the lower guide block mates with the groove of the shoe guide, and the small end of the lower guide block mates with the concave hole on the lower end face of the lower retaining ring.

[0007] Preferably, the upper and lower locking plates have the same structure, each including multiple segments with the same structure. After the segments are enclosed, the upper and lower ends are fixed by locking plate rings to form an upper or lower locking plate. The outer walls of both the upper and lower locking plates are inlaid with ceramic teeth. The upper end face of the upper locking plate has a concave hole that mates with the upper guide block, and the lower end of the inner wall of the upper locking plate mates with the upper conical surface of the outer wall of the upper cone. The lower end face of the lower locking plate has a concave hole that mates with the lower guide block, and the upper end of the inner wall of the lower locking plate mates with the upper conical surface of the outer wall of the lower cone.

[0008] Preferably, the upper cone and the lower cone have the same structure and are both fixed to the central tube by shear pins; the upper end of the upper extension is hinged to the lower end of the upper cone, and the upper end of the lower extension is hinged to the upper end of the lower cone.

[0009] Preferably, the upper extension body and the lower extension body have the same structure, both including a rotating shaft and an extension body; the rotating shaft of the upper extension body is hinged to the lower end of the upper cone, and the inner wall of the extension body mates with the conical surface of the outer wall of the upper cone; the rotating shaft of the lower extension body is hinged to the upper end of the lower cone, and the inner wall of the extension body mates with the conical surface of the outer wall of the lower cone.

[0010] Preferably, the upper cone and the lower cone have the same structure and are connected to the central tube by a shear pin; the upper end of the outer wall of the upper cone mates with the lower end of the inner wall of the upper extension, and the lower end of the outer wall of the lower cone mates with the upper end of the inner wall of the lower extension.

[0011] Preferably, the rubber sleeve is made of soluble rubber with a length-to-diameter ratio of 2.5; the outer wall of the upper end of the rubber sleeve mates with the conical surface of the inner wall of the lower end of the upper back ring, and the outer wall of the lower end mates with the conical surface of the inner wall of the upper end of the lower back ring.

[0012] Preferably, the upper back ring and the lower back ring have the same structure, both including an inner back ring and an outer back ring.

[0013] Preferably, the release ring and the guide shoe are fixedly connected to the central tube by threads. The release ring includes upper and lower sections, and pulling off the upper and lower sections completes the release of the bridge plug.

[0014] The beneficial effects of this invention are as follows: When the bridge plug pump is delivered to the predetermined layer, the cable is ignited. The cable setting tool transmits thrust through the setting sleeve to push the slip stop ring, guide block, slip, cone, extension body, secondary cone, rubber sleeve, and back ring downwards. After being stressed, the extension body opens radially along the secondary cone. The rubber sleeve and back ring move downwards along the central tube and expand radially, sealing the annular space between the central tube and the sleeve. When the force generated by the setting tool reaches the starting force value of the slip ring, the slip opens radially along the conical surface of the cone. At the same time, the slip drives the guide block to... The slipper moves radially along the grooves of the stop ring and guide shoe. When the slipper reaches the outer diameter of the cone, it continues to move radially through the open outer cone surface of the extension body until it bites into the inner wall of the casing, simultaneously forming a self-locking mechanism with the extension body and the secondary cone. When the force generated by the setting tool reaches the breakage force value of the release ring thread, the setting tool disengages from the bridge plug, completing the setting process. The setting tool, along with the setting sleeve and pull rod, is removed from the wellhead. When fracturing of the producing formation above the bridge plug is required, a ball-pump is used to pump soluble balls onto the inner cone surface of the upper part of the central tube, which is then sealed before fracturing. After fracturing, the soluble bridge plug will self-dissolve in a liquid with a certain temperature and chloride ion concentration, forming a full-bore channel inside the casing.

[0015] The soluble ball of this invention is made of soluble metal material, and the rubber sleeve is made of soluble rubber material. The small outer diameter can be sealed in a larger casing inner diameter (a 70mm outer diameter soluble bridge plug can seal a 115mm casing inner diameter). Under certain temperature and salinity, the bridge plug can be completely dissolved, eliminating the need for continuous tubing drilling and meeting the development needs of deep shale gas casing wells. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the soluble bridge plug for casing wells according to the present invention;

[0017] Figure 2 This is a cross-sectional view of the soluble bridge plug for casing wells according to the present invention;

[0018] Figure 3 This is a schematic diagram of the upper or lower locking mechanism;

[0019] Figure 4 This is a schematic diagram of the structure of the lock ring;

[0020] Figure 5 This is a schematic diagram of the structure of an upper or lower cone;

[0021] Figure 6 A schematic diagram of the structure of the upper or lower extension body;

[0022] Figure 7 This is a structural diagram of the upper guide block or the lower guide block;

[0023] Figure 8 This is a structural diagram of the shoe.

[0024] In the diagram: 1. Release ring; 2. Central tube; 3. Vest stop ring; 31. Vest stop ring groove; 4. Upper guide block; 41. Large end; 42. Small end; 5. Upper vestibule; 51. Split; 52. Vest ring mounting groove; 53. Ceramic tooth inlay groove; 54. Concave hole; 6. Upper cone; 61. Outer wall mating surface; 62. Rotating shaft mounting groove; 7. Upper extension body; 71. Rotating shaft; 72. Extension body; 8. Upper cone; 9. Upper back ring; 10. Rubber sleeve; 11. Lower back ring; 12. Lower cone; 13. Lower extension body; 14. Pressure plate; 15. Lower cone; 16. Lower vestibule; 17. Lower guide block; 18. Guide shoe; 181. Guide shoe groove; 19. Vest ring. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] like Figure 1-8 As shown, a soluble bridge plug for variable wells according to the present invention includes a soluble ball, a release ring 1, a central tube 2, a slip ring 3, a rubber sleeve 10, and a guide shoe 18. The upper end of the inner hole of the central tube 2 opens outward to form a conical hole for placing the soluble ball. The release ring 1 is fixedly disposed on the outer circular surface of the upper end of the central tube 2, and the guide shoe 18 is fixedly disposed on the outer circular surface of the lower end of the central tube 2. Between the release ring 1 and the rubber sleeve 10, the slip ring 3, the upper guide block 4, the upper slip 5, the upper cone 6, the upper extension 7, the upper secondary cone 8, and the upper back ring 9 are sequentially disposed on the outer circular surface of the central tube 2. Between the guide shoe 18 and the rubber sleeve 10, the lower guide block 17, the lower slip 16, the lower cone 15, the lower extension 13, the lower secondary cone 12, and the lower back ring 11 are sequentially disposed on the outer circular surface of the central tube 2.

[0027] The soluble bridge plug of the present invention is connected to the setting tool and inserted into the well via a bridge plug setting connector package. The upper thread of the release ring 1 is connected to the pull rod and then thread fastening glue is applied. The lower end face of the pusher cylinder contacts the upper stepped surface of the slip stop ring 3. When the bridge plug pump reaches the predetermined level, the cable ignites. The cable setting tool transmits thrust through the setting sleeve, pushing the slip stop ring 3, guide blocks (upper guide block 4, lower guide block 17), slips (upper slip 5, lower slip 16), cones (upper cone 6, lower cone 15), extensions (upper extension 7, lower extension 13), secondary cones (upper secondary cone 8, lower secondary cone 12), rubber sleeve 10, and back rings (upper back ring 9, lower back ring 11) downwards. Under force, the extensions open radially along the secondary cones (upper extension 7 opens radially along the upper secondary cone 8, lower extension 13 opens radially along the lower secondary cone 12). The rubber sleeve 10 and back rings (9, 11) move downwards along the central tube, accompanied by radial expansion, sealing the center. In the annulus between pipe 2 and casing, when the force generated by the setting tool reaches the starting force value of slip ring 19, the slips open radially along the conical surface of the cone (upper slip 5 opens radially along the conical surface of upper cone 6, and lower slip 16 opens radially along the conical surface of lower cone 15). Simultaneously, the slips drive the corresponding guide blocks to move radially along the grooves of slip stop ring 3 and guide shoe 18 (slip stop ring groove 31 and guide shoe groove 181). When the slips (5, 16) reach the outer diameter of cone (6, 15), they continue to move radially through the opened outer conical surface of extension body (7, 13) until they bite into the inner wall of casing, simultaneously forming a self-locking mechanism with extension body (7, 13) and secondary cone (8, 12). When the force generated by the setting tool reaches the thread breakage force value of release ring 1, the setting tool disengages from the bridge plug, completing the setting process. The setting tool, along with the setting sleeve and pull rod, is removed from the wellhead. When fracturing the producing layer above the bridge plug is required, a soluble plug is pumped onto the inner conical surface of the upper part of the central tube 2 using a ball-pumping system. After sealing, fracturing is performed. After the fracturing operation is completed, the soluble bridge plug will dissolve spontaneously in a liquid with a certain temperature and chloride ion concentration, forming a full-bore channel inside the casing.

[0028] Combination Figure 2 As shown, in this embodiment, the inner hole at the upper end of the central tube 2 has a 30° conical hole, and the soluble ball can be placed at the conical hole to seal the central tube 2 after the bridge plug is set.

[0029] Combination Figure 4 As shown, in this embodiment, the outer surface of the locking ring 3 is flush with the outer surface of the release ring 1, and is fixedly connected to the central tube by a shear pin to prevent premature action; the locking ring 3 is provided with a locking ring groove 31 that cooperates with the upper guide block 4, which can increase the support space for the radial movement of the upper locking ring 5; combined with Figure 8 The guide shoe 18 is provided with a guide shoe groove 181 that cooperates with the lower guide block 17, which can increase the support space for the radial movement of the lower slip 16.

[0030] Combination Figure 7As shown, in this embodiment, the upper guide block 4 and the lower guide block 17 have the same structure, both including a large end 41 and a small end 42. The large end 41 of the upper guide block 4 engages with the groove 31 of the retaining ring, and the small end 42 of the upper guide block 4 engages with the recess 54 on the upper end face of the upper retaining ring 5. The large end 41 of the lower guide block 17 engages with the groove 181 of the shoe guide, and the small end 42 of the lower guide block 17 engages with the recess 54 on the lower end face of the lower retaining ring 16. The retaining rings (5, 16) move radially while simultaneously driving the corresponding guide blocks (4, 17) to move radially.

[0031] Combination Figure 3 As shown, in this embodiment, the upper slip 5 and the lower slip 16 have the same structure, both including multi-lobed segments 51. After the multi-lobed segments 51 are enclosed, the upper and lower ends are fixed by slip rings 19 to form the upper slip 5 or the lower slip 16. The slip rings 19 are set in the slip ring mounting grooves 52 on the outer circular surfaces of the upper and lower ends of the upper slip 5 or the lower slip 16 to fix the multi-lobed segments 51. By setting an accurate breaking force, the slip rings 19 can prevent the upper slip 5 or the lower slip 16 from breaking midway, thus preventing premature sealing. Both the upper slip 5 and the lower slip 16 have ceramic tooth inlay grooves 53 on their outer walls for inlaying ceramic teeth. The upper end face of the upper slip 5 has a recessed hole 54 that mates with the upper guide block 4. The lower end of the inner wall of the upper slip 5 mates with the upper conical surface of the outer wall of the upper cone 6, with a taper of 20°. The lower end face of the lower slip 16 has a recessed hole 54 that mates with the lower guide block 17. The upper end of the inner wall of the lower slip 16 mates with the upper conical surface of the outer wall of the lower cone 15, with a taper of 20°.

[0032] Combination Figure 5 As shown, in this embodiment, the upper cone 6 and the lower cone 15 have the same structure and are both fixed to the central tube 2 by shear pins to prevent premature movement. The upper cone 6 is provided with a rotating shaft mounting groove 62, and the rotating shaft 71 of the upper extension 7 is installed in the rotating shaft mounting groove 62 by a torsion spring and a pressure plate 14. The outer wall surface of the upper cone 6 is provided with an outer wall mating surface 61, which mates with the inner wall conical surface of the upper clamp 5, with a taper of 20°. The lower cone 15 is provided with a rotating shaft mounting groove 62, and the rotating shaft 71 of the lower extension 13 is installed in the rotating shaft mounting groove 62 by a torsion spring and a pressure plate 14. The outer wall surface of the lower cone 15 is provided with an outer wall mating surface 61, which mates with the inner wall conical surface of the lower clamp 16, with a taper of 20°.

[0033] Combination Figure 6As shown, in this embodiment, the upper extension 7 and the lower extension 13 have the same structure, both including a rotating shaft 71 and an extension body 72. The rotating shaft 71 of the upper extension 7 is hinged to the lower end of the upper cone 6, and the inner wall of the extension body 72 mates with the outer conical surface of the upper secondary cone 8, with a taper of 20°. The rotating shaft 71 of the lower extension 13 is hinged to the upper end of the lower cone 15, and the inner wall of the extension body 72 mates with the outer conical surface of the lower secondary cone 15, with a taper of 20°. Both the upper extension 7 and the lower extension 13 are equipped with torsion springs on their rotating shafts 71. During the insertion of the bridge plug into the well, the torsion springs press the extension body close to the central tube 2. When the bridge plug sets, the extension body opens outward along the secondary cone, increasing the support for the radial movement of the slip, which can ensure a larger slip setting range. The outer wall surface of the extension body 72 has a 10° plane, which, after opening, can serve as a support surface for the slip after it exceeds the outer diameter of the bridge plug body.

[0034] In this embodiment, the upper cone 8 and the lower cone 12 have the same structure and are connected to the central tube 2 by a shear pin to prevent premature action; the upper end of the outer wall of the upper cone 8 is engaged with the lower end of the inner wall of the upper extension 7, and the lower end of the outer wall of the lower cone 12 is engaged with the upper end of the inner wall of the lower extension 13.

[0035] In this embodiment, the rubber sleeve 10 is made of soluble rubber, which can dissolve on its own in water and at high temperatures. The length-to-diameter ratio of the rubber sleeve 10 reaches 2.5. There is a 15° conical surface at each of the upper and lower ends of the rubber sleeve 10, which corresponds to and cooperates with the upper back ring 9 and the lower back ring 11, so as to seal a larger range of sleeve annulus.

[0036] In this embodiment, the upper back ring 9 and the lower back ring 11 have the same structure, both including an inner back ring and an outer back ring. The inner and outer back rings have an internal angle of 15°. There are 12 evenly distributed slits on both the inner and outer back rings. The slits of the inner and outer back rings are staggered and bonded together with adhesive. The small-angle back ring can provide a larger annular support and protection for the rubber tube.

[0037] In this embodiment, the release ring 1 and the guide shoe 18 are both fixedly connected to the central tube 2 by threads. The release ring 1 can be designed as a two-section structure, including upper and lower sections. Pulling off the upper and lower sections completes the release of the bridge plug.

[0038] Combination Figure 8 As shown, in this embodiment, the upper end of the guide shoe 18 is evenly distributed with guide shoe grooves 181 that mate with the large end of the lower guide block 17, which can support the lower slip to seal a larger range of casing; the lower end of the guide shoe 18 is provided with a conical surface, which plays a guiding role when entering the well.

[0039] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims.

[0040] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention should be considered within the protection scope of the present invention.

Claims

1. A soluble bridge plug for use in variable wells, characterized in that: The device includes a soluble ball, a release ring, a central tube, a locking ring, a rubber sleeve, and a guide shoe. The upper end of the inner hole of the central tube opens outward to form a conical hole for placing the soluble ball. The release ring is fixedly disposed on the outer circular surface of the upper end of the central tube, and the guide shoe is fixedly disposed on the outer circular surface of the lower end of the central tube. Between the release ring and the rubber sleeve, a locking ring, an upper guide block, an upper locking ring, an upper cone, an upper extension, an upper secondary cone, and an upper back ring are sequentially disposed on the outer circular surface of the central tube. Between the guide shoe and the rubber sleeve, a lower guide block, a lower locking ring, a lower cone, a lower extension, an lower secondary cone, and a lower back ring are sequentially disposed on the outer circular surface of the central tube. The outer surface of the locking ring is flush with the outer surface of the release ring and is fixedly connected to the central tube by a shear pin; the locking ring is provided with a locking ring groove that mates with the upper guide block; the guide shoe is provided with a guide shoe groove that mates with the lower guide block. The upper guide block and the lower guide block have the same structure, each including a large end and a small end. The large end of the upper guide block mates with the groove of the retaining ring of the slip, and the small end of the upper guide block mates with the concave hole on the upper end face of the upper slip. The large end of the lower guide block mates with the groove of the shoe guide, and the small end of the lower guide block mates with the concave hole on the lower end face of the lower slip. The upper and lower extension bodies have the same structure, both including a rotating shaft and an extension body; the rotating shaft of the upper extension body is hinged to the lower end of the upper cone, and the inner wall of the extension body mates with the conical surface of the outer wall of the upper cone; the rotating shaft of the lower extension body is hinged to the upper end of the lower cone, and the inner wall of the extension body mates with the conical surface of the outer wall of the lower cone.

2. The soluble bridge plug for casing wells according to claim 1, characterized in that: The upper and lower locking plates have the same structure, both including multiple segments with the same structure. After the segments are enclosed, the upper and lower ends are fixed by locking plate rings to form an upper locking plate or a lower locking plate. The outer walls of the upper and lower locking plates are inlaid with ceramic teeth. The upper end face of the upper locking plate has a concave hole that mates with the upper guide block, and the lower end of the inner wall of the upper locking plate mates with the upper conical surface of the outer wall of the upper cone. The lower end face of the lower locking plate has a concave hole that mates with the lower guide block, and the upper end of the inner wall of the lower locking plate mates with the upper conical surface of the outer wall of the lower cone.

3. The soluble bridge plug for casing wells according to claim 1, characterized in that: The upper and lower cones have the same structure and are both fixed to the central tube by shear pins; the upper end of the upper extension is hinged to the lower end of the upper cone, and the upper end of the lower extension is hinged to the upper end of the lower cone.

4. The soluble bridge plug for casing wells according to claim 1, characterized in that: The upper cone and the lower cone have the same structure and are connected to the central tube by shear pins; the upper end of the outer wall of the upper cone mates with the lower end of the inner wall of the upper extension, and the lower end of the outer wall of the lower cone mates with the upper end of the inner wall of the lower extension.

5. The soluble bridge plug for casing wells according to claim 1, characterized in that: The rubber tube is made of soluble rubber with a length-to-diameter ratio of 2.5; the outer wall of the upper end of the rubber tube fits with the conical surface of the inner wall of the lower end of the upper back ring, and the outer wall of the lower end fits with the conical surface of the inner wall of the upper end of the lower back ring.

6. The soluble bridge plug for casing wells according to claim 1, characterized in that: The upper and lower back rings have the same structure, both including an inner back ring and an outer back ring.

7. The soluble bridge plug for casing wells according to claim 1, characterized in that: The release ring and the guide shoe are fixedly connected to the central tube by threads. The release ring includes upper and lower sections. Pulling off the upper and lower sections completes the release of the bridge plug.

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