Soluble bridge plug with dissolution starting mechanism

Abstract

The invention relates to the technical field of oil field oil production engineering, in particular to a soluble bridge plug with a dissolution starting mechanism. The invention is characterized in that a ball seat dissolving surface (1-1) is arranged on the outer surface of the middle part of the ball seat (1), a push ring dissolving surface (2-1) is arranged on the contact surface of the push ring (2) and the slip (3), a slip dissolving surface (3-1) is arranged on the contact surface of the slip (3) and the cone (4), a cone dissolving surface (4-1) is arranged on the contact surface of the cone (4) and the slip (3), and a baffle ring dissolving surface (6-1) is arranged on the contact surface of the baffle ring (6) and the slip (3); and corrosion inhibition coatings are arranged on the surfaces except for the dissolving surface. The soluble bridge plug can be started to dissolve after setting and during fracturing, realizes non-dissolution before setting, slow dissolution before fracturing after setting and rapid dissolution after fracturing, and meets the environmental requirements of high temperature, high pressure, high salinity or acidic fracturing fluid for unconventional tight reservoir fracturing construction.

Description

Technical Field

[0001] The invention relates to the technical field of oil field production engineering, in particular to a soluble bridge plug with a dissolving start mechanism. Background Art

[0002] Conventional soluble bridge plugs currently used in large-scale fracturing of unconventional tight reservoirs are made from soluble alloys. Surface coatings such as resin spraying, butter, micro-arc oxidation, and baking varnish are used to slow the initial corrosion rate in high-temperature, high-pressure, and highly mineralized wellbore fluid environments, thereby extending the effective pressure-bearing time. However, the protective performance of the corrosion-inhibiting coating and the solubility of the soluble alloy material are two conflicting indicators for soluble bridge plug tools. For acidic wellbore fluid environments, the corrosion inhibition performance of the soluble bridge plug needs to be enhanced. However, better protective coating measures may result in the soluble bridge plug not dissolving quickly after fracturing, or even not dissolving at all, increasing drilling costs and the risk of stuck plugs before production. Summary of the Invention

[0003] In order to overcome the deficiency of existing soluble bridge plugs that may not dissolve quickly after fracturing after adding a coating that can reliably isolate well fluid, the present invention provides a soluble bridge plug with a dissolution start mechanism. The soluble bridge plug can start to dissolve after setting and during fracturing, so as to achieve no dissolution before setting, slow dissolution after setting and before fracturing, and rapid dissolution after fracturing, thereby meeting the high temperature, high pressure, high mineralization or acidic fracturing fluid environment requirements of unconventional tight reservoir fracturing construction.

[0004] The technical solution of the present invention is: a soluble bridge plug with a dissolution starting mechanism, including a ball seat, a rubber cylinder is provided on the outside of the ball seat, cones are provided at both ends of the rubber cylinder, the outside of the cone cooperates with the slip through an inclined surface, a push ring is provided at the upper end of the upper slip, and the lower end of the ball seat is connected to the retaining ring, which is characterized in that: a ball seat dissolving surface is provided on the outer surface of the middle part of the ball seat, a push ring dissolving surface is provided on the surface where the push ring contacts the slip, a slip dissolving surface is provided on the surface where the slip contacts the cone, a cone dissolving surface is provided on the surface where the cone contacts the slip, and a retaining ring dissolving surface is provided on the surface where the retaining ring contacts the slip; and corrosion-inhibiting coatings are provided on the surfaces of the ball seat, push ring, slip, cone and retaining ring except for the corresponding dissolving surfaces.

[0005] The ball seat dissolving surface, the push ring dissolving surface, the slip dissolving surface, the cone dissolving surface and the retaining ring dissolving surface are not provided with a corrosion inhibition coating.

[0006] The push ring dissolution surface is located on the inner side of the contact surface between the push ring and the slips.

[0007] The push ring dissolving surface is annular, the inner diameter of the annular ring is the inner diameter of the push ring, and the outer diameter of the annular ring is smaller than the outer diameter of the push ring.

[0008] The slip dissolution surface is located outside the contact surface between the slip and the cone.

[0009] The outer edge of the slip dissolution surface does not coincide with the outer edge of the contact surface between the slip and the cone.

[0010] The cone dissolution surface is located on the inner side of the contact surface between the cone and the slips.

[0011] The inner edge of the cone dissolution surface does not coincide with the inner edge of the contact surface between the cone and the slip.

[0012] The dissolving surface of the retaining ring is located on the inner side of the contact surface between the retaining ring and the slips.

[0013] The dissolving surface of the retaining ring is annular, the inner diameter of the annular ring is the inner diameter of the retaining ring, and the outer diameter of the annular ring is smaller than the outer diameter of the retaining ring.

[0014] The present invention has the following beneficial effects: due to the adoption of the above scheme, the soluble bridge plug is provided with a dissolving surface without coating on each component with a corrosion-inhibiting coating, and each dissolving surface together constitutes a dissolving starting mechanism. Before the soluble bridge plug is set, the dissolving starting control mechanism is closed and does not work. After the soluble bridge plug is set, the dissolving starting control mechanism is partially started. When the fracturing ball is thrown under pressure to start fracturing, the dissolving starting control mechanism is fully opened, and the soluble bridge plug begins to dissolve normally, achieving no dissolution before setting, slow dissolution after setting, and rapid dissolution after fracturing, thereby meeting the high temperature, high pressure, high mineralization or acidic fracturing fluid environment requirements of unconventional tight reservoir fracturing construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of a soluble bridge plug with a dissolving start mechanism before it is set and when the dissolving start mechanism is not working; Figure 2 This is a schematic diagram of the dissolution start mechanism of the soluble bridge plug after it is set and the dissolution start mechanism is partially working; Figure 3 This is a schematic diagram of a soluble bridge plug with a dissolving start mechanism when the dissolving start mechanism is fully operational after being subjected to pressure.

[0016] In the figure, 1-ball seat, 2-push ring, 3-slip, 4-cone, 5-rubber cylinder, 6-blocking ring, 7-steel ball, 1-1-ball seat dissolving surface, 2-1-push ring dissolving surface, 3-1-upper slip dissolving surface, 3-2-lower slip dissolving surface, 4-1-upper cone dissolving surface, 4-2-lower cone dissolving surface, 6-1-blocking ring dissolving surface. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings: Depend on Figures 1 to 3As shown, a soluble bridge plug with a dissolution start mechanism includes a ball seat 1, a rubber sleeve 5 is provided on the outside of the ball seat 1, cones 4 are provided at both ends of the rubber sleeve 5, the outside of the cone 4 cooperates with the slip 3 through an inclined surface, a push ring 2 is provided on the upper end of the upper slip 3, and the lower end of the ball seat 1 is connected to the retaining ring 6. In the soluble bridge plug with a dissolution start mechanism, the contact surfaces of each part are provided with a dissolution surface, and no corrosion-inhibiting coating is provided on the dissolution surface. The surfaces of the parts other than the dissolution surface are all provided with a corrosion-inhibiting coating. The corrosion-inhibiting coating is a corrosion-resistant material that can slow down the dissolution rate of the parts in the downhole fluid. Since there is no corrosion-inhibiting coating on the dissolution surface of each part, a dissolution start mechanism is formed. When it is exposed to the well fluid, the dissolution rate of the soluble bridge plug with a dissolution start mechanism is accelerated. At the same time, considering the dissolution rate of the soluble bridge plug, some parts such as the push ring 2 and the retaining ring 6 can be processed with easily soluble materials.

[0018] The central outer surface of the ball seat 1 is provided with a ball seat dissolving surface 1-1. No corrosion-inhibiting coating is applied to this surface, but all surfaces of the ball seat 1 other than the dissolving surface 1-1 are provided with a corrosion-inhibiting coating. This surface 1-1 is located in the middle section of the cylindrical portion of the ball seat 1. Before and during the setting of the soluble bridge plug with a dissolving activation mechanism, the dissolving surface 1-1 is enclosed within the rubber sleeve 5 and the cone 4. During fracturing, as the ball seat 1 descends relative to the rubber sleeve 5, the dissolving surface 1-1 is exposed from within the rubber sleeve 5 and the cone 4, coming into contact with the well fluid, thereby accelerating the dissolution rate of the ball seat 1.

[0019] The push ring 2 is provided with a push ring dissolving surface 2-1 on the surface in contact with the slip 3. No corrosion-inhibiting coating is provided on the push ring dissolving surface 2-1. All surfaces of the push ring 2 except the push ring dissolving surface 2-1 are provided with corrosion-inhibiting coating. The push ring dissolving surface 2-1 is located on the inner side of the contact surface between the push ring 2 and the slip 3, that is, on the side close to the ball seat 1. The push ring dissolving surface 2-1 is annular, and the inner diameter of the annular ring is the inner diameter of the push ring 2, and the outer diameter of the annular ring is smaller than the outer diameter of the push ring 2. Before the soluble bridge plug with a dissolving start mechanism is set, the push ring dissolving surface 2-1 is in full contact with the slip 3 and is enclosed inside by the slip 3; when the soluble bridge plug with a dissolving start mechanism is set, the slip 3 moves outward under the push of the cone 4, thereby exposing the push ring dissolving surface 2-1 and contacting with the well fluid, thereby accelerating the dissolution rate of the push ring 2.

[0020] The surface of the slip 3 in contact with the cone 4 is provided with a slip dissolving surface 3-1. No corrosion-inhibiting coating is applied to the slip dissolving surface 3-1. All surfaces of the slip 3 except the slip dissolving surface 3-1 are provided with a corrosion-inhibiting coating. The slip dissolving surface 3-1 is located outside the contact surface between the slip 3 and the cone 4, and the outer edge of the slip dissolving surface 3-1 does not overlap with the outer edge of the contact surface between the slip 3 and the cone 4. This prevents the slip dissolving surface 3-1 from contacting the wellbore fluid and dissolving prematurely before the soluble bridge plug with a dissolving activation mechanism is set. Before the soluble bridge plug with a dissolving activation mechanism is set, the slip dissolving surface 3-1 is in full contact with the cone 4 and is enclosed within the cone 4. After the soluble bridge plug with a dissolving activation mechanism is set, the slip 3 moves outward under the push of the cone 4 and is set in the wellbore, exposing the slip dissolving surface 3-1 and bringing it into contact with the wellbore fluid, thereby accelerating the dissolution rate of the slip 3.

[0021] The surface of the cone 4 in contact with the slips 3 is provided with a cone dissolving surface 4-1. No corrosion-inhibiting coating is provided on the cone dissolving surface 4-1. All surfaces of the cone 4 except the cone dissolving surface 4-1 are provided with a corrosion-inhibiting coating. The cone dissolving surface 4-1 is located on the inner side of the contact surface between the cone 4 and the slips 3, i.e., on the side close to the ball seat 1. The inner edge of the cone dissolving surface 4-1 does not overlap with the inner edge of the contact surface between the cone 4 and the slips 3. In other words, the inner edge of the cone dissolving surface 4-1 is some distance away from the lower edge of the inclined surface of the cone 4 and does not overlap. This prevents the cone dissolving surface 4-1 from coming into contact with well fluid and dissolving prematurely before the soluble bridge plug with a dissolving activation mechanism is set. Before the soluble bridge plug with a dissolution start mechanism is set, the cone dissolution surface 4-1 is in complete contact with the slips 3 and is sealed inside by the slips 3; after the soluble bridge plug with a dissolution start mechanism is set, the slips 3 move outward under the push of the cone 4 and are set on the wellbore, thereby exposing the cone dissolution surface 4-1 and contacting the well fluid, thereby accelerating the dissolution rate of the cone 4.

[0022] The surface of the retaining ring 6 in contact with the slip 3 is provided with a retaining ring dissolving surface 6-1. No corrosion-inhibiting coating is provided on the retaining ring dissolving surface 6-1. All surfaces of the retaining ring 6 except the retaining ring dissolving surface 6-1 are provided with a corrosion-inhibiting coating. The retaining ring dissolving surface 6 is located on the inner side of the contact surface between the retaining ring 6 and the slip 3, that is, on the side close to the ball seat 1. The retaining ring dissolving surface 6 is annular, with the inner diameter of the annular ring being the inner diameter of the retaining ring 6 and the outer diameter of the annular ring being smaller than the outer diameter of the retaining ring 6. Before the soluble bridge plug with a dissolving start mechanism is set, the retaining ring dissolving surface 6-1 is in full contact with the slip 3 and is enclosed inside by the slip 3. After the soluble bridge plug with a dissolving start mechanism is set, the slip 3 moves outward under the push of the cone 4 and is set on the wellbore, thereby exposing the retaining ring dissolving surface 6-1 and contacting the well fluid, thereby accelerating the dissolution rate of the retaining ring 6.

[0023] Before the soluble bridge plug with a dissolution start mechanism is set, the dissolution start control mechanism composed of various dissolution surfaces is completely sealed and does not come into contact with the well fluid. Therefore, the soluble bridge plug with a dissolution start mechanism does not dissolve. After the soluble bridge plug with a dissolution start mechanism is set, part of the dissolution start control mechanism, including the push ring dissolution surface 2-1, the slip dissolution surface 3-1, the cone dissolution surface 4-1, and the retaining ring dissolution surface 6-1, is released from the sealed state, and the components corresponding to the above-mentioned dissolution surfaces begin to slowly dissolve from the dissolution surfaces. When the steel ball 7 is put into the well to bear pressure, the ball seat 1 is forced downward by the pressure, and the ball seat dissolution surface 1-1 is exposed to the well fluid, causing the ball seat 1 to begin to dissolve rapidly from this point. The dissolution start control mechanism can effectively increase the effective pressure-bearing time of the soluble bridge plug tool with a dissolution start mechanism, and at the same time, it can also achieve rapid dissolution after fracturing. It is suitable for fracturing construction in some special environments such as high temperature, high mineralization, and acidic fracturing fluid.

Claims

1. A soluble bridge plug with a dissolving start mechanism, comprising a ball seat (1), a rubber sleeve (5) provided on the outside of the ball seat (1), cones (4) provided at both ends of the rubber sleeve (5), the outside of the cone (4) being matched with a slip (3) through an inclined surface, a push ring (2) provided on the upper end of the slip (3), and a retaining ring (6) connected to the lower end of the ball seat (1), characterized in that: The outer surface of the middle portion of the ball seat (1) is provided with a ball seat dissolving surface (1-1), the surface of the push ring (2) in contact with the slip (3) is provided with a push ring dissolving surface (2-1), the surface of the slip (3) in contact with the cone (4) is provided with a slip dissolving surface (3-1), the surface of the cone (4) in contact with the slip (3) is provided with a cone dissolving surface (4-1), and the surface of the retaining ring (6) in contact with the slip (3) is provided with a retaining ring dissolving surface (6-1); and the surfaces of the ball seat (1), the push ring (2), the slip (3), the cone (4), and the retaining ring (6) other than the corresponding dissolving surfaces are all provided with a corrosion inhibition coating.

2. The soluble bridge plug with a dissolution initiation mechanism according to claim 1, characterized in that: No corrosion-inhibiting coating is provided on the ball seat dissolving surface (1-1), the push ring dissolving surface (2-1), the slip dissolving surface (3-1), the cone dissolving surface (4-1), and the retaining ring dissolving surface (6-1).

3. The soluble bridge plug with a dissolution initiation mechanism according to claim 2, characterized in that: The push ring dissolving surface (2-1) is located on the inner side of the contact surface between the push ring (2) and the slip (3).

4. The soluble bridge plug with a dissolution initiation mechanism according to claim 3, characterized in that: The push ring dissolving surface (2-1) is annular, the inner diameter of the annular ring is the inner diameter of the push ring (2), and the outer diameter of the annular ring is smaller than the outer diameter of the push ring (2).

5. The soluble bridge plug with a dissolution initiation mechanism according to claim 2, characterized in that: The slip dissolving surface (3-1) is located outside the contact surface between the slip (3) and the cone (4).

6. The soluble bridge plug with a dissolution initiation mechanism according to claim 5, characterized in that: The outer edge of the slip dissolution surface (3-1) does not coincide with the outer edge of the contact surface between the slip (3) and the cone (4).

7. The soluble bridge plug with a dissolution initiation mechanism according to claim 2, characterized in that: The cone dissolution surface (4-1) is located on the inner side of the contact surface between the cone (4) and the slip (3).

8. The soluble bridge plug with a dissolution initiation mechanism according to claim 7, characterized in that: The inner edge of the cone dissolution surface (4-1) does not coincide with the inner edge of the contact surface between the cone (4) and the slip (3).

9. The soluble bridge plug with a dissolution initiation mechanism according to claim 2, characterized in that: The retaining ring dissolving surface (6) is located on the inner side of the contact surface between the retaining ring (6) and the slip (3).

10. The soluble bridge plug with a dissolution initiation mechanism according to claim 9, characterized in that: The retaining ring dissolving surface (6) is annular, the inner diameter of the annular ring is the inner diameter of the retaining ring (6), and the outer diameter of the annular ring is smaller than the outer diameter of the retaining ring (6).

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