Dissolvable bridge plug for offshore fracturing precise timing galvanic corrosion of self-constructed primary battery

Abstract

The invention relates to the technical field of oil and gas field development, and provides a soluble bridge plug for galvanic corrosion of an offshore fracturing precise timing self-constructed primary battery, the upper end of a central shaft is in threaded connection with a locking cap, and the lower end of the central shaft is in threaded connection with a release sub; the central shaft is sleeved with the mandrel, the upper end of the mandrel is in threaded connection with the upper slip base, and the upper slip base, the upper cone, the upper protection bowl, the soluble rubber cylinder, the lower protection bowl and the lower cone are sequentially arranged on the mandrel in a sleeving mode. The slip insert is arranged on the outer wall of the lower slip bowl; the lower slip bowl is of a cylindrical structure, and a conical hole in the upper end of the lower slip bowl is sleeved on the outer wall of the lower end of the lower cone. The locking joint is of a cylindrical structure and is sleeved on the central shaft, and the lower end part of the locking joint is in threaded connection with the upper end part of the releasing joint; the base is of a cylindrical structure, is sleeved on the central shaft and is in threaded connection with the lower slip bowl; and cathode materials forming galvanic corrosion with the dissolvable bridge plug are uniformly arranged in large components such as the lower cone and the like. The cathode material can be dissolved in fracturing fluid, and full-bore production of an oil well is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a soluble bridge plug for offshore fracturing with precise timing and self-constructed galvanic couple corrosion. Background Art

[0002] With the continuous exploitation and consumption of oil and gas resources, the focus of oil and gas exploitation has shifted to unconventional oil and gas resources such as shale gas and tight oil. The reservoir matrix of shale gas is porous and dense, with almost no natural production capacity. Horizontal drilling technology and staged fracturing technology are required to produce stable production. The key point of staged fracturing technology lies in the effectiveness of plugging tools in isolating the wellbore. Bridge plugs are one of the core downhole tools required for unconventional oil and gas such as shale gas to achieve production increase and transformation. In the process of horizontal well staged fracturing operations, bridge plugs play the role of temporarily isolating the target well section.

[0003] Now the bridge plug staged fracturing adopts the joint technology of perforating and bridge plug setting. When the bridge plug, setting tool and perforating gun are pumped to the position, the bridge plug is set first. After the setting is completed, the perforating gun is lifted up to perforate. After perforating, the wellbore tool string is pulled out and the soluble ball is pumped. After the ball sits on the bridge plug center pipe, fracturing begins. After fracturing is completed, the soluble bridge plug has failed at this time, but there is still a large volume that has not dissolved. It will continue to dissolve slowly at the same dissolution rate as when the setting is effective.

[0004] Usually, one method is to wait for the fracturing fluid to be completely dissolved before returning it. This takes a long time, which will result in the failure to return the fracturing fluid in time, causing the formation to be polluted, and will also delay the well opening, and fail to open the well in time to generate economic benefits. Another method is to use continuous tubing to drill and plug the well, and drill and wear away the bridge plug that has not been completely dissolved. This will incur additional and expensive operating costs. Summary of the invention

[0005] The object of the present invention is to solve at least one technical problem in the background technology and to provide a dissolvable bridge plug for offshore fracturing with precise timing and self-constructed galvanic couple corrosion.

[0006] To achieve the above object, the present invention provides a dissolvable bridge plug for offshore fracturing with precise timing and self-constructed galvanic couple corrosion, comprising:

[0007] Central axis, upper slip base, mandrel, upper slip seat, anti-blocking shear nails, upper cone, upper protective bowl, soluble rubber tube, lower protective bowl, lower cone, slip teeth, lower slip seat, locking joint, base;

[0008] The upper end of the central shaft is threadedly connected to the locking cap, and the lower end is threadedly connected to the release joint;

[0009] The mandrel is sleeved on the central shaft, the upper end of the mandrel is threadedly connected to the upper slip base, and the upper slip base, the upper cone, the upper protective bowl, the soluble gel tube, the lower protective bowl and the lower cone are sleeved on the mandrel in sequence from top to bottom;

[0010] The slip teeth are arranged on the outer wall of the lower slip seat;

[0011] The lower slip seat is a cylindrical structure, and the conical hole at the upper end thereof is sleeved on the outer wall of the lower end of the lower cone;

[0012] The locking joint is a cylindrical structure, sleeved on the central shaft, and its lower end is threadedly connected with the upper end of the release joint;

[0013] The base is a cylindrical structure, sleeved on the central axis, and connected to the lower slip seat;

[0014] The invention is characterized in that cathode materials which form galvanic corrosion with the soluble bridge plug are evenly arranged in the lower cone, the central axis, the upper vertebral body and the base.

[0015] According to one aspect of the present invention, the cathode material is in an annular mesh structure laid on the inner wall of the lower vertebral body.

[0016] According to one aspect of the present invention, the cathode material is steel, stainless steel or brass.

[0017] According to one aspect of the present invention, the core shaft is a cylindrical structure, and a stop thread is provided in the inner hole of the lower end portion thereof.

[0018] According to one aspect of the present invention, the upper slip seat is a cylindrical structure, and the conical hole at the lower end thereof is sleeved on the outer wall of the upper end of the upper cone.

[0019] According to one aspect of the present invention, the upper protective bowl and the lower protective bowl are cylindrical structures, the upper protective bowl is installed at the upper end of the soluble colloid tube, and the lower protective bowl is installed at the lower end of the soluble colloid tube.

[0020] According to one aspect of the present invention, a conical hole is provided at the upper end of the lower cava seat, and a connecting thread is provided at the root of the conical hole. The lower cava seat is sleeved on the outer conical surface of the lower cone and locked with the lower cone through the connecting thread, and a plurality of grooves are evenly processed at the upper end of the lower cava seat.

[0021] According to the solution of the present invention, the offshore fracturing precise timing self-constructed galvanic cell galvanic corrosion soluble bridge plug includes: a central axis, an upper slip base, a core shaft, an upper slip seat, anti-blocking shear nails, an upper cone, an upper protective bowl, a soluble glue cylinder, a lower protective bowl, a lower cone, a slip tooth, a lower slip seat, a locking joint, and a base; the upper end of the central axis 1 is threadedly connected to the locking cap, and the lower end is threadedly connected to the hand-release joint; the core shaft is sleeved on the central axis, the upper end of the core shaft is threadedly connected to the upper slip base, the upper slip seat, the upper cone, the upper protective bowl, the lower cone, the slip teeth, the lower slip seat, the locking joint, and the base; the upper end of the central axis 1 is threadedly connected to the locking cap, and the lower end is threadedly connected to the hand-release joint; the core shaft is sleeved on the central axis, the upper end of the core shaft is threadedly connected to the upper slip base, the upper slip seat, the upper cone, the upper protective bowl, the lower cone, the lower protective bowl, the lower cone, the lower protective bowl, the lower slip seat, the lower cone, the upper protective bowl, the lower cone, the upper protective bowl, the lower slip seat, the lower cone, the upper protective bowl, the lower cone, the upper protective bowl, the lower slip seat, the lower cone, the upper protective bowl, the lower cone, the upper protective bowl, the lower slip seat, the upper cone, the upper protective bowl ... The bowl, soluble gel tube, lower protective bowl and lower cone are sequentially mounted on the core shaft from top to bottom; the slip teeth are arranged on the outer wall of the lower slip seat; the lower slip seat is a cylindrical structure, and the conical hole at its upper end is mounted on the outer wall of the lower end of the lower cone; the locking joint is a cylindrical structure, which is sleeved on the central axis, and its lower end is threadedly connected with the upper end of the release joint; the base is a cylindrical structure, which is sleeved on the central axis and connected to the lower slip seat; cathode materials that form galvanic corrosion with the soluble bridge plug are evenly arranged in large components such as the lower cone. Such arrangement can make it possible that when the bridge plug is set, the central axis is relatively immobile, the upper cava base and the core shaft are pushed forward together, the upper cava base expands outward along the upper cone, and at the same time pushes the upper protective bowl, the soluble gel tube, the lower protective bowl, the lower cone, the lower cava base, and the base to move forward, the soluble gel tube is compressed and expanded, and at the same time the lower cava base expands outward along the cone surface of the lower cone, when the lower cava base expands to a certain extent, the anchors on the upper cava base and the anchors on the lower cava base are eaten into the inner wall of the casing, the soluble gel tube expands to the inner wall of the casing, and the threads of the central axis are cut off, completing the setting of the soluble bridge plug. After the bridge plug is set, a soluble ball is put in to block the inner hole on the core shaft, the upper and lower parts of the bridge plug are isolated, and the target layer section is fracturing. The structure of the present invention isolates the pressure-bearing components of the bridge plug from the fracturing fluid after the bridge plug is set, slows down the dissolution rate of the pressure-bearing components, ensures fracturing construction, and is suitable for high-mineralization fracturing. Moreover, mesh ring-shaped cathode materials are added to large components such as the lower cone. After the bridge plug is seated and fracturing is completed, the bridge plug is immersed in the return fluid and dissolved to a certain depth to expose the cathode material, so that the cathode material and the bridge plug body form a primary battery with precise timing, causing galvanic corrosion, accelerating the rapid dissolution of the soluble bridge plug, greatly shortening the waiting period of the oil well, and quickly putting it into production.

[0022] According to the solution of the present invention, the structure of the soluble bridge plug provided by the present invention can meet the conditions of high temperature and high mineralization to ensure fracturing construction; the annular mesh cathode material added to large components such as the lower cone can be quickly dissolved in the fracturing fluid, greatly shortening the well shutdown period; the preferred mesh annular cathode material can be dissolved in the fracturing fluid to ensure full-bore production of the oil well. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A cross-sectional view schematically showing a structural arrangement of a dissolvable bridge plug for self-constructing galvanic corrosion of an offshore fracturing precisely timed according to an embodiment of the present invention;

[0024] Figure 2 A schematic diagram showing the structural arrangement of a mandrel according to an embodiment of the present invention;

[0025] Figure 3 The structural layout of the lower slip seat according to one embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0026] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the present invention, rather than implying any limitation on the scope of the present invention.

[0027] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0028] Figure 1 A schematic cross-sectional view of the structure arrangement of a dissolvable bridge plug for offshore fracturing with precise timing and self-constructed galvanic couple corrosion according to an embodiment of the present invention is shown. Figure 1 As shown, in this embodiment, the offshore fracturing accurately timed self-constructed galvanic couple corrosion soluble bridge plug includes:

[0029] Central axis 1, upper slip base 2, mandrel 3, upper slip base 4, anti-blocking shear nail 5, upper cone 6, upper protective bowl 7, soluble rubber tube 8, lower protective bowl 9, lower cone 10, slip teeth 11, lower slip base 12, locking joint 13, base 14;

[0030] The upper end of the central shaft 1 is threadedly connected to the locking cap 15, and the lower end is threadedly connected to the release joint (not shown in the figure);

[0031] The mandrel 3 is sleeved on the central shaft 1, the upper end of the mandrel 3 is threadedly connected with the upper slip base 2, and the upper slip base 4, the upper cone 6, the upper protective bowl 7, the soluble gel tube 8, the lower protective bowl 9 and the lower cone 10 are sleeved on the mandrel 3 in sequence from top to bottom;

[0032] The slip teeth 11 are arranged on the outer wall of the lower slip seat 12;

[0033] The lower slip seat 12 is a cylindrical structure, and the conical hole at the upper end thereof is sleeved on the outer wall of the lower end of the lower cone 10;

[0034] The locking joint 13 is a cylindrical structure, sleeved on the central shaft 1, and its lower end is threadedly connected with the upper end of the release joint;

[0035] The base 14 is a cylindrical structure, sleeved on the central shaft 1, and connected to the lower slip seat 12;

[0036] In this embodiment, the cathode material that forms galvanic corrosion with the soluble bridge plug is evenly arranged on the lower cone 10, the central axis 1, the upper vertebral body 6, and the base 14. In this way, when the bridge plug is set, the central axis 1 is relatively immobile, the upper slip base 2 and the core shaft 3 are pushed forward together, the upper slip seat 4 expands outward along the upper cone 6, and at the same time pushes the upper protection bowl 7, the soluble gel cylinder 8, the lower protection bowl 9, the lower cone 10, the lower slip seat 12, and the base 14 to move forward, the soluble gel cylinder 8 is compressed and expanded, and at the same time the lower slip seat 12 expands outward along the cone surface of the lower cone 10, when the lower slip seat 12 expands to a certain extent, the anchors on the upper slip seat 4 and the anchors on the lower slip seat 12 are eaten into the inner wall of the casing, the soluble gel cylinder 8 expands to the inner wall of the casing, and the thread of the central axis 1 is cut off, completing the setting of the soluble bridge plug. After the bridge plug is set, a soluble ball is put in to block the inner hole on the core shaft 3, the upper and lower parts of the bridge plug are isolated, and the target layer section is fractured. The structure of the present invention isolates the pressure-bearing components of the bridge plug from the fracturing fluid after the bridge plug is set, slows down the dissolution rate of the pressure-bearing components, ensures fracturing construction, and is suitable for high-mineralization fracturing. In addition, a mesh annular cathode material is added to large components such as the lower cone. After the bridge plug is set and fracturing is completed, the bridge plug is immersed and dissolved in the return fluid to a certain depth to expose the cathode material, so that the cathode material and the bridge plug body accurately and timedly form a primary battery, galvanic corrosion occurs, and the rapid dissolution of the soluble bridge plug is accelerated, which greatly shortens the waiting period of the oil well and quickly puts it into production.

[0037] Furthermore, if Figure 1 As shown, according to one embodiment of the present invention, one end of the anti-blocking shear pin 5 is supported on the core shaft 3, and the other end is supported on the upper vertebral body 6. The provision of the anti-blocking shear pin 5 can prevent the bridge plug from being prematurely sealed when encountering resistance during the process of going down into the well. The anti-blocking shear pin 5 can make the bridge plug resist the resistance and be correctly sealed after falling into place.

[0038] Further, according to one embodiment of the present invention, the cathode material is in an annular mesh structure laid on the inner wall of the lower cone 10. Such an arrangement can enable the annular mesh cathode material to form galvanic corrosion with the soluble bridge plug body, and can be completely dissolved in the fracturing fluid to ensure full-bore production of the oil well. Among them, the mesh structure is easy to plasticize and cut, has a low manufacturing cost and is practical, can be evenly distributed in the material, and will not reduce the overall dissolution rate of the bridge plug due to dissolution and detachment.

[0039] Further, in this embodiment, the cathode material is made of steel, stainless steel or brass.

[0040] Further, according to one embodiment of the present invention, Figure 2As shown, the mandrel 3 is a cylindrical structure, and a stop thread 16 is provided in the inner hole of the lower end thereof. With such a configuration, when the locking joint 13 moves forward, the locking thread at the upper end of the locking joint 13 can be engaged and locked with the stop thread at the lower end of the mandrel 3. The stop thread cooperates with other components of the bridge plug to effectively prevent the slips from moving and greatly improve the stability of the slip setting. The stop thread can ensure the stability of the bridge plug, improve the sealing performance, simplify the structural design, and promote the dissolution of the bridge plug.

[0041] Further, according to one embodiment of the present invention, the upper slip seat 4 is a cylindrical structure, and the conical hole at the lower end thereof is sleeved on the outer wall of the upper end of the upper cone 6.

[0042] Further, according to one embodiment of the present invention, the upper protective bowl 7 and the lower protective bowl 9 are cylindrical structures, the upper protective bowl 7 is installed at the upper end of the soluble gel tube 8, and the lower protective bowl 9 is installed at the lower end of the soluble gel tube 8.

[0043] Furthermore, if Figure 3 As shown, according to one embodiment of the present invention, a conical hole 19 is provided at the upper end of the lower slip seat 12, a connecting thread 17 is provided at the root of the conical hole 19, the lower slip seat 12 is sleeved on the outer cone surface of the lower cone 10 and is locked with the lower cone 10 through the connecting thread 17, and a plurality of grooves 18 are evenly processed at the upper end of the lower slip seat 12. The opening and tightening of the grooves 18 realize smooth installation and fixation.

[0044] Furthermore, it is worth noting that the soluble bridge plug dissolves in the fracturing fluid. During the dissolution process of the bridge plug, it is assumed that the surface of the bridge plug dissolves uniformly and at a constant rate, and that the dissolution depth of the bridge plug per unit time is h. M represents the mass of the bridge plug, and ΔM represents the change in the mass of the bridge plug.

[0045]

[0046] but:

[0047]

[0048] Where: ΔM is the mass change per unit time, g; ρ is the density of the material, g / cm 3 ; d is the diameter of the bridge plug, mm; h is the depth of dissolution per unit time, mm; v h is the dissolution rate per unit time, mm / h or mm / s. From this, we can know the mass change of the dissolution process of the soluble bridge plug of the present invention and the dissolution rate.

[0049] According to the above scheme of the present invention, the structure of the soluble bridge plug provided by the present invention can meet the conditions of high temperature and high mineralization to ensure fracturing construction; the annular mesh cathode material added to large components such as the lower cone can be quickly dissolved in the fracturing fluid, greatly shortening the well shutdown period; the preferred mesh annular cathode material can be dissolved in the fracturing fluid to ensure the full-bore production of the oil well.

[0050] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. Offshore fracturing precision timing self-constructed galvanic couple corrosion soluble bridge plug, including: Central axis (1), upper slip base (2), mandrel (3), upper slip seat (4), anti-shear nail (5), upper cone (6), upper protective bowl (7), soluble rubber tube (8), lower protective bowl (9), lower cone (10), slip teeth (11), lower slip seat (12), locking joint (13), base (14); The upper end of the central shaft (1) is threadedly connected to the locking cap, and the lower end is threadedly connected to the release joint; The core shaft (3) is sleeved on the central shaft (1), the upper end of the core shaft (3) is threadedly connected to the upper slip base (2), and the upper slip base (4), the upper cone (6), the upper protective bowl (7), the soluble gel tube (8), the lower protective bowl (9) and the lower cone (10) are sleeved on the core shaft (3) in sequence from top to bottom; The slip teeth (11) are arranged on the outer wall of the lower slip seat (12); The lower slip seat (12) is a cylindrical structure, and the conical hole at the upper end thereof is sleeved on the outer wall of the lower end of the lower cone (10); The locking joint (13) is a cylindrical structure, sleeved on the central shaft (1), and its lower end is threadedly connected to the upper end of the release joint; The base (14) is a cylindrical structure, sleeved on the central shaft (1), and connected to the lower slip seat (12); The invention is characterized in that cathode materials which form galvanic corrosion with the soluble bridge plug are evenly arranged in the lower cone (10), the central axis (1), the upper cone (6) and the base (14).

2. The offshore fracturing precise timing self-constructed galvanic cell galvanic corrosion soluble bridge plug according to claim 1, characterized in that: The cathode material is in the form of an annular mesh structure laid on the inner wall of the lower vertebral body (10).

3. The offshore fracturing precise timing self-constructed galvanic cell galvanic corrosion soluble bridge plug according to claim 1, characterized in that: The cathode material is made of steel, stainless steel or brass.

4. The offshore fracturing precise timing self-constructed galvanic cell galvanic corrosion soluble bridge plug according to claim 1, characterized in that: The core shaft (3) is a cylindrical structure, and a stop thread (16) is arranged in the inner hole of the lower end portion thereof.

5. The offshore fracturing precise timing self-constructed galvanic cell galvanic corrosion soluble bridge plug according to claim 1, characterized in that: The upper slip seat (4) is a cylindrical structure, and the conical hole at the lower end thereof is sleeved on the outer wall of the upper end of the upper cone (6).

6. The offshore fracturing precise timing self-constructed galvanic cell galvanic corrosion soluble bridge plug according to claim 1, characterized in that: The upper protective bowl (7) and the lower protective bowl (9) are cylindrical structures. The upper protective bowl (7) is installed on the upper end of the soluble colloid tube (8), and the lower protective bowl (9) is installed on the lower end of the soluble colloid tube (8).

7. The offshore fracturing precise timing self-constructed galvanic cell galvanic corrosion soluble bridge plug according to any one of claims 1-6, characterized in that: A conical hole is arranged at the upper end of the lower cava seat (12), and a connecting thread (17) is arranged at the root of the conical hole. The lower cava seat (12) is mounted on the outer conical surface of the lower cone (10) and is locked with the lower cone (10) via the connecting thread (17). A plurality of grooves (18) are evenly processed at the upper end of the lower cava seat (12).

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