Ball valve with dissolvable ball

A ball valve can include a housing that contains a flow path and a ball positioned in the flow path. The ball can be configured to seal a first portion of the flow path from a second portion of the flow path in a closed position, and at least a portion of the ball can be dissolvable and the ball can include a bore formed therethrough.

BACKGROUND

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the described embodiments. Accordingly, it should be understood that these statements are to be read in this light and not as admissions of prior art.

Wellbores are sometimes drilled into subterranean formations containing hydrocarbons to allow recovery of the hydrocarbons. During the drilling and production of a hydrocarbon bearing formation, various procedures may be performed that involve temporarily isolating fluid flowing between the surface of a wellbore and the formation through a wellbore tubular. Such procedures can include flow control operations, completion operations, and/or interventions. Various valves, including ball valves, may be used during these procedures to control the flow of fluid through the wellbore tubular. Ball valves generally include a ball seat for receiving a sealing ball. In some situations, ball valves may fail during use, which may reduce the ability to establish fluid communication between the surface of the wellbore and the formation through the wellbore tubular. In some instances, should the ball become stuck in a closed position, the only way to gain access to the reservoir below the ball is to mill the ball, which is often a time and resource consuming operation.

DETAILED DESCRIPTION

The present disclosure relates to a downhole ball valve that includes a ball that includes one or more portions that are dissolvable. In the event that the ball valve becomes stuck or otherwise unable to establish fluid communication in a flow path, the ball can be partially dissolved and partially milled away or entirely dissolved in order to establish fluid communication.

FIG. 1depicts an example well system100that includes a downhole ball valve150. As depicted, the operating environment comprises a workover and/or drilling rig106that is positioned on the earth's surface104and extends over and around a wellbore114that penetrates a subterranean formation102for the purpose of recovering hydrocarbons. The wellbore114may be drilled into the subterranean formation102using any suitable drilling technique. The illustrated wellbore114extends substantially vertically away from the earth's surface104over a vertical wellbore portion116and an annulus112is defined between the wellbore114and the tubing string120(and other downhole tools in the wellbore114). In alternative operating environments, all or portions of the wellbore114may be vertical, deviated at any suitable angle, horizontal, and/or curved. The wellbore114may be a new wellbore, an existing wellbore, a straight wellbore, an extended reach wellbore, a sidetracked wellbore, a multi-lateral wellbore, and other types of wellbores for drilling and completing one or more production zones. Further the wellbore114may be used for both producing wells and injection wells, and may be completely cased, partially cased, or open hole (e.g., uncased).

A wellbore tubular string120that includes the ball valve150may be lowered into the subterranean formation102for a variety of purposes (e.g., injecting or producing fluids from the wellbore, workover or treatment procedures, etc.) throughout the life of the wellbore114. The implementation shown inFIG. 1illustrates the wellbore tubular120in the form of a production tubing string that includes a packer140disposed in the wellbore114. The wellbore tubular120that includes the ball valve150is equally applicable to any type of wellbore tubular being inserted into a wellbore as part of a procedure needing fluid isolation from above or below the ball valve, including as non-limiting examples drill pipe, segmented pipe, casing, rod strings, and coiled tubing. Further, techniques of isolating the interior of the wellbore tubular string120from the annular region between the wellbore tubular string120and the wellbore wall114may take various forms. For example, a zonal isolation device such as a packer (e.g., packer140), may be used to isolate the interior of the wellbore tubular string120from the annular region to allow for the ball valve150to control the flow of a fluid through the wellbore tubular120. In some implementations, the wellbore tubular string120that includes the ball valve150may be used without any additional zonal isolation device (e.g., a packer).

In some embodiments, the workover and/or drilling rig106may comprise a derrick108with a rig floor110through which the wellbore tubular120extends downward from the drilling rig106into the wellbore114. The workover and/or drilling rig106may comprise a motor driven winch and other associated equipment for extending the wellbore tubular120into the wellbore114to position the wellbore tubular120at a selected depth. While the operating environment depicted inFIG. 1refers to a stationary workover and/or drilling rig106for conveying the wellbore tubular120comprising the ball valve150within a land-based wellbore114, in alternative implementations, mobile workover rigs, wellbore servicing units (such as coiled tubing units), and the like may be used to lower the wellbore tubular120comprising the ball valve150into the wellbore114. The wellbore tubular120comprising the ball valve150may alternatively be used in other operational environments, such as within an offshore wellbore operational environment.

Regardless of the type of operational environment in which the ball valve150is used, the ball valve150comprises a flow through device that serves to control a flow of fluid from the surface to a formation (and vice-versa) through a tubular or conduit, including situations in which the ball valve150fails to actuate (e.g., fails to open or be adjusted from a closed position).

The ball valve150may also comprise components (e.g., a threaded connection) located above or below the ball valve150to allow the ball valve150to be disposed within and/or coupled to a wellbore tubular and/or other wellbore components (e.g., production subs, downhole tools, screens, etc.), for example, to form a workstring, production string, conveyance string, etc. While the following discussion describes a wellbore tubular120with a ball valve150, it should be understood that any plurality of ball valves150comprising the flow through device may be used in one or more wellbore tubular120strings to achieve the results and advantages described herein.

FIG. 2depicts a cross-section view of a portion of an example ball valve250, which, in some aspects, may be used as the ball valve150in the system100.FIG. 2illustrates the valve250within the wellbore114, and in a closed position. In one or more embodiments, the ball valve250includes a housing202, such as a tubular housing, that may be coupled (e.g., threadingly) to other downhole components, in a downhole string or otherwise, that are uphole and/or downhole of the valve250. The housing202includes a flow path formed therein. In the illustrated implementation, the housing202is a single piece tubular component or multi-piece component that encloses other components of the valve250therein.

The ball valve250further includes a ball204which includes a bore210formed therethrough. When the ball valve250is in the closed position, the bore210is turned orthogonal to the flow path201of the valve250. In an open position (not shown), the bore210of the ball204may be turned to align (e.g., completely, substantially, or partially) with the flow path201to allow fluid communication through the valve250. In one or more embodiments, the ball204is positioned in the flow path201such as to divide the flow path201into a first portion214and a second portion216. Over the course of an operation, the first and second portions may have the same pressure or a pressure differential. The two portions of the flow path201can also be considered an uphole portion214and a downhole portion216.

The ball204may also have a top side206and a bottom side208, in which the top side206faces the uphole portion214of the flow path20land the bottom side208faces the downhole portion216of the flow path201when the valve250is in the closed position. In certain applications, higher pressure may be applied onto the bottom side208of the ball204than onto the top side206of the ball204. Typically, in such embodiments, the downhole portion of the flow path201is the portion to be sealed (e.g., to prevent upward flow of reservoir fluid). Thus, the bottom side208of the ball204can be configured to provide adequate sealing and requires adequate structural strength. The top side206of the ball204may be subject to lesser load and therefore may have less structural strength than otherwise if subjected to greater load. As such, a portion of the top side206can be filled with, contain, or otherwise include one or more dissolvable materials.

In one or more embodiments, the ball204is made of a material based on, for example, pressure requirements to seal the valve250against flow in the closed position. The ball204of the valve250may also include a portion or portions that are made of a different material that is dissolvable. Such dissolvable portions may be dissolved if the valve fails and the need to establish fluid communication by intervention arises. The ball204may also include a non-dissolvable portion fabricated from a material capable of providing structural support and withstanding high pressure at the valve250. Thus, when intervention is required to establish fluid communication through the valve250, the dissolvable portion of the ball204is dissolved away and a hole is milled or otherwise formed in the non-dissolvable portion. In some applications, the ball204is oriented such that at least some of the non-dissolvable portion is subject to the higher pressures of the wellbore114. Thus, the ball204can effectively prevent fluids from escaping the wellbore114.

As shown inFIG. 2, the top side206of the ball204, adjacent the bore210, includes a hole211that is formed (e.g., bored, milled, or otherwise formed) within the ball204. In some aspects, the hole211may extend from the outer surface of the top side206through to the bore210, thereby putting the low pressure portion of the flow path in fluid communication with the bore210. In alternative aspects, the hole211may extend from the outer surface of the top side206toward the bore210, but may not reach the bore210.

In one or more embodiments, the hole211is filled with a dissolvable material212, and is different from a base material from which the ball204is formed. The dissolvable material212may be in solid form or fluid form when applied to the ball204. In the embodiment ofFIG. 2, the bottom side208of the ball204may be made of the base material, and a portion of the top side206, such as the portion that surrounds the hole211, is made of the base material. The dissolvable material may be relatively and/or significantly easier to dissolve than the base material. For example, the dissolvable material may be dissolvable by a solvent that would not dissolve the base material.

In one or more embodiments, the dissolvable material use to fill the ball204may be dissolvable when acted upon by a dissolving agent. The dissolving agent may be provided to the ball204from the surface via the flow path201. The dissolvable materials can be or include, but are not limited to, magnesium, aluminum, gallium, alloys thereof, or any mixture thereof. In some examples, the dissolvable material can be or include one or more magnesium alloys and/or one or more aluminum alloys. The dissolving agents can be or include, but are not limited to, one or more acids, one or more bromides, one or more chlorides, or any mixture thereof. For example, the dissolving agent can be or include calcium bromide, hydrochloric acid, brine (e.g., sodium chloride and/or other salts in water), or any mixture thereof. Specifically, in one example, completion fluid that contains calcium bromide may be used in an operation, and the dissolvable material in the ball204may include a magnesium alloy, which is readily reactive with and dissolvable by calcium bromide.

The non-dissolvable base material used to fabricate the ball204may include a hard, structurally strong material such as a metal, metal alloy, plastic, a composite material, among others. Non-limiting examples of the base material can be or include non-corrosive steel, one or more INCONEL® alloys, one or more nickel-chromium alloys, one or more stainless steels, alloys thereof, or any mixture thereof. In some embodiments, the entire ball204may be fabricated from a dissolvable material.

FIG. 3depicts a cross-section view of another example of a downhole ball valve350. In the embodiment of the valve350shown inFIG. 3, a bottom side308of the ball304includes a cavity327formed therein. Similar to a hole311formed in top side306, the cavity327may also be filled with a dissolvable material328.

In the illustrated implementation ofFIG. 3, the cavity327is shaped to approximate a cone, pyramid, or the like. The illustrated cavity327extends from the bore310towards the outer surface of bottom side308of the ball304. As shown, however, the cavity327does not extend to meet the outer surface of the bottom side308of the ball304, thereby leaving at least a layer of the base material between the bore310and the flow path301. In one or more embodiments, the cavity327may extend through to the downhole portion of the flow path301.

As illustrated inFIG. 3, the portions of the ball304that are filled with the dissolvable material (e.g., hole311and cavity327) are arranged so as to provide a relatively centralized fluid path through the ball304(orthogonal to the bore310) once the dissolvable material is dissolved. Thus, in embodiments in which some base material still remains between the centralized fluid path and the high pressure portion of the flow path301, a hole can be more easily formed therethrough as there is significantly less material to mill or otherwise remove.

The present disclosure also provides a method of establishing flow through a ball valve. Typically, such techniques are used when the ball valve is unable to open or establish flow through normal operation, and intervention is required. The method includes introducing a dissolving agent to a ball of the ball valve, in which the ball comprises at least a dissolvable portion. The dissolving agent can be introduced to the ball by injection downhole and dissolves away the dissolvable portion(s) of the ball substantially either substantially instantly or over a period of time. In some embodiments, when the dissolvable portion(s) of the ball are dissolved away, a layer of non-dissolvable base material remains and separates the uphole portion of the flow path from the downhole portion of the flow path. In such embodiments, the method includes forming a hole though said remaining base material, thus establishing flow through the ball valve. In one or more embodiments, the hole may be formed by a milling operation.

In one or more embodiments, the ball can include dissolvable material all the way through such that when the dissolvable material is dissolved, a hole is left in the ball which provides flow through the ball valve even though the ball remains in the closed position. In such embodiments, no other hole needs to be formed or milled.

In another embodiment, the ball includes a metal or non-dissolvable skin312covering the dissolvable material. Thus, when intervention is required, the non-dissolvable skin312is punctured or at least partially removed to exposed the dissolvable material. The dissolvable material can then be dissolved as described above.

The present disclosure further provides a method of fabricating ball valves150,250,350(FIGS. 1-3), as well as other ball valves. According to one or more embodiments, the method includes obtaining or fabricating a ball made of a base material such as that described above. A hole is then formed in at least a portion of the ball. The cavity may extend from a region of the surface of the ball into the ball. In some embodiments, the cavity ends within the ball and does not extend completely through the ball. In one or more embodiments, the cavity extends through the ball, forming a path from one surface region to another surface region.

The method further includes filling the cavity with a dissolvable material such as that described above. The dissolvable material may be sintered, subjected to a cryogenic process, or another curing process in order to be integrated into the ball and solidified. The method further includes forming a bore through the ball. In some embodiments, the bore is formed after the dissolvable material is integrated into the ball. In some other embodiments, the bore is formed before the dissolvable material is integrated into the ball. In some embodiments, the bore is generally orthogonal to the direction of the cavity containing the dissolvable material.

Various implementations of the ball valve according to the present disclosure may include none, one or some of the following features. For example, the ball valve may reduce rig and/or work time in the case of a “fail closed” situation where the valve may need to be milled (e.g., bored, cut, or otherwise milled) through to achieve fluid communication therethrough. As another example, the ball valve may be able to withstand design wellbore pressures while also allowing mill through capability in the case of a fail closed situation. In another example, the ball valve may facilitate a centralizing of a mill through when milling (or boring or cutting or dissolving) through particular portions of the ball.

In addition to the embodiments described above, embodiments of the present disclosure further relate to one or more of the following paragraphs:

1. A ball valve, comprising: a housing comprising a flow path; and a ball positioned in the flow path and configured to seal a first portion of the flow path from a second portion of the flow path in a closed position, the ball comprising a bore formed therethrough, and at least a portion of the ball being dissolvable.

2. A ball valve, comprising: a housing comprising a flow path; and a ball positioned in the flow path and configured to seal a first portion of the flow path from a second portion of the flow path in a closed position, the ball comprising a bore formed therethrough, and the ball comprises a dissolvable portion and a non-dissolvable portion.

3. A ball valve, comprising: a housing comprising a flow path; and a ball positioned in the flow path and configured to seal a first portion of the flow path from a second portion of the flow path in a closed position, the ball comprising a bore formed therethrough, and the ball comprises a dissolvable portion and a non-dissolvable portion, wherein the dissolvable portion comprises magnesium, aluminum, gallium, alloys thereof, or any mixture thereof, and wherein the non-dissolvable portion comprises a non-corrosive steel, a nickel-chromium alloy, a stainless steel, alloys thereof, or any mixture thereof.

4. The ball valve of any one of paragraphs 1-3, wherein the dissolvable portion is in a solid state and dissolvable when acted upon by a dissolving agent.

5. The ball valve of paragraph 4, wherein the dissolvable portion comprises magnesium, aluminum, gallium, alloys thereof, or any mixture thereof.

6. The ball valve of paragraph 4, wherein the dissolving agent comprises an acid, a bromide, a chloride, or any mixture thereof.

7. The ball valve of any one of paragraphs 1-6, wherein the ball comprises the dissolvable portion and a non-dissolvable portion.

8. The ball valve of paragraph 7, wherein the non-dissolvable portion comprises a non-corrosive steel, a nickel-chromium alloy, a stainless steel, alloys thereof, or any mixture thereof.

9. The ball valve of paragraph 7, wherein the non-dissolvable portion of the ball is positioned adjacent to a relatively high pressure side of the flow path, and configured to seal the relatively high pressure side of the flow path.

10. The ball valve of any one of paragraphs 1-9, wherein the entire ball is dissolvable when acted upon by a dissolving agent.

11. The ball valve of any one of paragraphs 1-10, wherein the dissolvable portion of the ball is positioned adjacent to a relatively low pressure side of flow path.

12. The ball valve of any one of paragraphs 1-11, wherein the ball is rotatable between the closed position and an opening position in which the bore is in fluid communication with the uphole portion of the flow path and the downhole portion of the flow path.

13. A method of establishing flow through the ball valve according to any one of paragraphs 1-12.

14. A method of fabricating the ball valve according to any one of paragraphs 1-12.

15. A method of establishing flow through a ball valve, comprising: introducing a dissolving agent to a ball of the ball valve; dissolving at least a portion of the ball; and establishing a flow path through the dissolved portion of the ball valve.

16. The ball valve or method of any one of paragraphs 1-15, further comprising forming a hole in a non-dissolved portion of the ball.

17. The method of paragraph 16, further comprising forming the hole in a non-dissolved portion of the ball via a milling operation.

18. The ball valve or method of any one of paragraphs 1-17, further comprising forming a hole in or at least partially removing a non-dissolvable skin covering a dissolvable portion of the ball.

19. The ball valve or method of any one of paragraphs 1-18, further comprising introducing the dissolving agent after failure of the ball valve to move from a closed position to an open position.

20. A method of fabricating a ball valve, comprising: forming a cavity at least partially through a ball; filling the cavity with a dissolvable material; and forming a bore through the ball.

21. The ball valve or method of any one of paragraphs 1-20, further comprising fabricating the ball from a base material more resistant to dissolving than the dissolvable material.

22. The ball valve or method of any one of paragraphs 1-21, further comprising integrating the dissolvable material within the ball.

23. The method of paragraph 22, wherein integrating the dissolvable material within the ball includes at least one of sintering the dissolvable material in place, subjecting the dissolvable material to a cryogenics process, or curing the dissolvable material.

24. The ball valve or method of any one of paragraphs 1-23, further comprising: forming a hole through the ball, wherein the hole extends from one surface region of the ball to another surface region of the ball; and filling the hole with the dissolvable material.

Certain terms are used throughout the description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function, unless specifically stated. In the discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. In addition, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. The use of “top,” “bottom,” “above,” “below,” and variations of these terms is made for convenience, but does not require any particular orientation of the components.