Operations performed and equipment utilized in conjunction with a subterranean production well often require one or more different types of valves. One such valve is a ball valve. A ball valve is a type of valve that uses a spherical ball valve member as a closure mechanism. The ball valve member has a hole there through that is aligned with the direction of flow when the valve is opened and misaligned with the direction of flow when the valve is closed.
Ball valves have many applications in well tools for use downhole in a wellbore, for example, as formation tester valves, safety valves, and in other downhole applications. Many of these well tool applications use a ball valve because their ball valve members can have a large through bore for passage of tools, tubing strings, and flow, yet may also be compactly arranged. For example, ball valves may have a cylindrical inner profile that corresponds to the cylindrical inner profile of the remainder of the tools that it associates with. During operations, the ball valve is subjected to extreme pressures, and as a result of these pressures, the exposed surface of the ball valve can become distorted.
Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
In the drawings and descriptions that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals, respectively. The drawn figures are not necessarily, but may be, to scale. Certain features of the disclosure may be shown exaggerated in scale or in somewhat schematic form and some details of certain elements may not be shown in the interest of clarity and conciseness. The present disclosure may be implemented in embodiments of different forms. Specific embodiments are described in detail and are shown in the drawings, with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed herein may be employed separately or in any suitable combination to produce desired results. Moreover, all statements herein reciting principles and aspects of the disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof. Additionally, the term, “or,” as used herein, refers to a non-exclusive or, unless otherwise indicated.
Unless otherwise specified, use of the terms “connect,” “engage,” “couple,” “attach,” or any other like term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described.
Unless otherwise specified, use of the terms “above,” “up,” “upper,” “upward,” “uphole,” “upstream,” or other like terms, including their use in the claims, shall be construed as generally toward the well surface; likewise, use of the terms “below,” “down,” “lower,” “downward,” “downhole,” or other like terms shall be construed as generally toward the bottom, terminal end of a well, regardless of the wellbore orientation. Use of any one or more of the foregoing terms is meant to be used to provide a general orientation or arrangement of the components within the device and with respect to each other and shall not be construed to require the device to be located in a well bore or to denote positions along a perfectly vertical or horizontal axis. Unless otherwise specified, use of the term “subterranean formation” shall be construed as encompassing both areas below exposed earth and areas below earth covered by water, such as ocean or fresh water. Further, any references to “first,” “second,” etc. do not specify a preferred order of method or importance, unless otherwise specifically stated, but such terms are for identification purposes only and are intended to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the embodiments of this disclosure. Moreover, a first element and second element may be implemented by a single element able to provide the necessary functionality of separate first and second elements.
Ball valve assemblies are currently used in the oil and gas industry and often utilize a metal to metal (m-t-m) seal to ball sealing arrangement. A seating member is biased towards the ball by means of a spring that is typically located above, or uphole, of a sealed boost piston, but the spring force is often insufficient alone to generate enough contact stress to maintain a gas tight seal over a range of pressures. Higher differential pressures require higher contact stresses to maintain a seal. Therefore, it is usual to incorporate a sealed boost piston that has upper and lower seals sized to be above and below the m-t-m seal point. This arrangement has the effect of causing the seating member to be pushed onto the ball with the applied wellbore pressure regardless of which direction the wellbore pressure is applied (above the ball or below). Though this arrangement works well and gives an increasing contact pressure, as the differential pressure increases it is subject to the loss of seal integrity, because depending on the direction of the applied pressure differential, the ball itself can be subjected to considerable loading, particularly when the pressure is applied from below (when the seat is located below the ball). In such instances, the large surface area within the m-t-m seal diameter is exposed to higher pressures, causing the ball to distort, resulting in a loss of seal integrity of the m-t-m seal.
The present disclosure recognizes that it is advantageous to reduce the amount of pressure exerted against the surface of a sealing ball valve member and reduce the amount of distortion that a sealing ball valve member may undergo during downhole high pressure situations. To achieve this, the embodiments of this disclosure provide a multi-ball valve assembly that lessens the pressure applied from either uphole or downhole directions by directing a portion of the pressure into a sealed fluid chamber area between the ball valve members. The disclosed embodiments utilize two or more stacked ball valve members that are operatively coupled together but are independently biased away from each other, allowing one or both to move towards one another under pressure. For example, pressure from below will move the lower ball valve member upward towards the uppermost ball valve member, and in a reverse pressure situation, pressure from above will move the upper ball valve member lower and towards the downhole positioned ball valve member. When both ball valve members are in a closed position, a closed volume of fluid is trapped between the ball valve members. If for instance, pressure is applied to the lower ball valve member from below, the lower ball valve member will attempt to move upward by its limited amount and compresses the fluid trapped in the closed volume. By limiting the travel of the lower ball valve member, this trapped pressure can be limited to be approximately half the applied pressure, thus halving the differential pressure across the lower ball valve member. The upper ball valve member will only see the differential pressure between what's trapped below it and the hydrostatic above. This way the stress on both ball valve members can be significantly reduced allowing for a greater chance of a seal between the ball valve member and the seating member.
In one embodiment, the ball valve members are fixed and the embodiment includes two pressure relief valves set at desired pressures, one allowing fluid to bypass the upper ball valve member to communicate with the void between the ball valve members and a lower pressure relief valve performing a similar action from below. When the ball valve members are shut, the effect is the same, that is, the differential across each ball valve member is greatly reduced.
Another embodiment includes ball valve members that are fixed axially and have two limited travel piston valves to increase pressure between the closed ball valve members. By using the ball valve assembly of this disclosure, either an uphole pressure or a downhole pressure can be stepped down multiple ball valve members located within the same ball housing, reducing the resultant differentials across each ball valve member and minimizing the deflection of the ball valve members' surface, thereby, improving the changes of a zero leak seal.
Referring to
The fluid/electrical connection 120 may extend into the well 160 and may be connected to the multi-ball valve assembly 130. The fluid/electrical connection 120 may provide actuation and/or de-actuation of the multi-ball valve assembly 130. Actuation may comprise opening the multi-ball valve assembly 130 to provide a flow path for wellbore fluids to exit the well 160, and de-actuation may comprise closing the multi-ball valve assembly 130 to close a flow path for wellbore fluids to exit the well 160.
The multi-ball valve assembly 130 may be interconnected to conduit 150. In one embodiment, the multi-ball valve assembly 130 is located above the well 160, as is shown in
Turning to
The multi-ball valve assembly 200 further includes one or more control arm(s) 235. In certain embodiments, the control arm(s) 235 includes a piston rod 235a that connects two separate portions of the control arm(s) 235 together and an isolation seal 235b. The illustrated embodiments show a control arm(s) 235 on each side of the first and second ball valve members 225, 230, however, other embodiments may have only one control arm. The control arm(s) 235 are coupled to and actionable on the first and second ball valve members 225, 230 to rotate them to open or closed positions. In one embodiment, the control arm(s) 235 are coupled to the first and second ball valve members 225, 230 by a control arm pin 235c and cam washer 235d in the ball slots 215b, 220b.
The embodiments of the multi-ball valve assembly 200 further comprise a first seating member 240 located between the first and second ball valve members 225, 230 and being slidably coupled to the ball housing 205 within the central bore 210. The first seating member 240 has a metal seat 240a located on a seating end thereof that is engagable against the first ball valve member 225 that forms a m-t-m seal. The second seating member 245 that is located downhole from the second ball valve member 230, has a metal seat 245a located on a seating end thereof that is engagable against the second ball valve member 230 that also forms a m-t-m seal. The first and second seating members 240, 245 are slideably captured within the central bore 210. In the illustrated embodiments, the first and second seating members 240, 245 are cylindrical, hollow tubes that have diameters that are exposed to the central bore 210 and through which well fluids can flow. Sealed boost pistons 240b and 245b may also be present that drive the first and second seating members 240, 245 against the first and second ball valve members 225, 230. When pressures are applied against the valve assembly 200, the first and second seating members 240, 245 are pushed toward the first and second ball valve members 225, 230, by the sealed boost pistons 240b and 245b that cause the metal seats 240a, 245a to engage their respective first and second ball valve members 225, 230. The metal seats 240a, 245a may be of known design, which are typically machined as a shoulder area on the end of the first and second seating members 240, 245.
The embodiments of
The invention having been generally described, the following embodiments are given by way of illustration and are not intended to limit the specification of the claims in any manner/
Embodiments herein comprise:
A valve assembly, comprising: a valve body having a ball housing with a central bore there through; first and second ball cages each located within a cavity formed in an interior diameter wall of the ball housing; first and second ball valve members located within and rotatably coupled to the first and second ball cages, respectively, and each having a bore there through and located in the ball housing for selective rotation between open and closed positions to control flow through the valve assembly. The first and second ball valve members define a fluid chamber area located within the central bore and between the first and second ball valve members. A control arm is coupled to the first and second ball valve members and is actionable on the first and second ball valve members to rotate the first and second ball valve members to the open or closed positions. A first seating member is located between the first and second ball valve members and is slidably coupled to the valve body adjacent the central bore and has a metal seat located on a seating end thereof that is engagable against the first ball valve member. A second seating member is located downhole from the second ball valve member and is engagable against the second ball valve member and has a metal seat located on a seating end thereof that is engagable against the second ball valve member.
Another embodiment is directed to a well system. In this embodiment, the well system comprises a string of tubing extending into a wellbore that is connected to a valve assembly and being supported from a rig support structure. The valve assembly comprising a valve body having a ball housing with a central bore there through; first and second ball cages each located within a cavity formed in an interior diameter wall of the ball housing; first and second ball valve members located within and rotatably coupled to the first and second ball cages, respectively, and each having a bore there through and located in the ball housing for selective rotation between open and closed positions to control flow through the valve assembly. The first and second ball valve members define a fluid chamber area located within the central bore and between the first and second ball valve members. A control arm is coupled to the first and second ball valve members and is actionable on the first and second ball valve members to rotate the first and second ball valve members to the open or closed positions. A first seating member is located between the first and second ball valve members and is slidably coupled to the valve body adjacent the central bore and has a metal seat located on a seating end thereof that is engagable against the first ball valve member. A second seating member is located downhole from the second ball valve member and is engagable against the second ball valve member and has a metal seat located on a seating end thereof that is engagable against the second ball valve member.
Element 1: wherein the first and second ball cages are slidable within each cavity, and further comprising: a first biasing member located between a wall of the cavity in which the first ball cage is located and the first ball cage and engaged against the first ball cage; and a second biasing member located between a wall of the cavity in which the second ball cage is located and the second ball cage and engaged against the second ball cage.
Element 2: wherein the first and second ball cages are axially fixed with respect to each other and further comprising: a pressure relief valve located within an interior diameter wall of the ball housing and positioned uphole or downhole from the fluid chamber area; a pressure communication port located in the ball housing that fluidly connects the pressure relief valve with the central bore; and a fluid port that has a first end that opens into the fluid chamber area of the ball housing and a second end that opens into a fluid path that extends from the fluid port to the pressure relief valve.
Element 3: wherein the pressure relief valve is set to divert a portion of the pressure exerted against the first or second ball valve member when in a closed position to a fluid located within the fluid chamber area through the fluid port.
Element 4: wherein the pressure relief valve is a first pressure relief valve located in a first cavity and uphole from the first ball valve member and further including a second pressure relief valve located within a second cavity formed in the interior diameter wall of the ball housing and downhole from the second ball valve member and wherein the fluid path extends from the fluid port to the first and second pressure relief valves.
Element 5: wherein the first and second pressure relief valves are set to divert a portion of the pressure exerted against the first or second ball valve member when in a closed position to a fluid located within the fluid chamber area through the fluid port.
Element 6: further comprising: a travel piston valve located within a cavity formed in an interior diameter wall of the ball housing and uphole or downhole from the fluid chamber area, the travel piston valve having a sealing member thereabout to provide a pressure seal about the travel piston valve; a travel piston valve communication port located in the ball housing that fluidly connects the travel piston valve with the central bore; and a fluid port having a first end that opens into the central bore of the ball housing and a second end that opens into a fluid path that extends from the port to the travel piston valve.
Element 7: wherein the travel piston valve is an assembly that further includes a biasing member located within the cavity that has a biasing constant that allows the biasing member to be compressed when a predetermined pressure is exerted against the travel piston valve.
Element 8: wherein the travel piston valve is a first travel piston valve located in a first cavity and uphole of the first ball valve member and further including a second travel piston valve located within a second cavity formed in the interior diameter wall of the ball housing and downhole of the second ball valve member and wherein the fluid path extends from the travel piston valve port to the first and second travel piston valves.
Element 9: wherein the first and second travel piston valves are first and second travel piston valve assemblies that each includes a biasing member located within the first and second cavities and that has a biasing constant that allows the biasing member to be compressed when a predetermined pressure is exerted against the first or second travel piston valves, respectively.
Element 10: wherein the first and second ball cages are slidable within each cavity of the first and second ball cages, and further comprising: a first biasing member located between a wall of the cavity in which the first ball cage is located and the first ball cage and engaged against the first ball cage; and a second biasing member located between a wall of the cavity in which the second ball cage is located and the second ball cage and engaged against the second ball cage.
Element 11: wherein the first and second ball cages are axially fixed with respect to each other and further comprising a pressure relief valve located within an interior diameter wall of the ball housing and positioned uphole or downhole from the fluid chamber area; a pressure communication port located in the ball housing that fluidly connects the pressure relief valve with the central bore; and a fluid port that has a first end that opens into the fluid chamber area of the ball housing and a second end that opens into a fluid path that extends from the fluid port to the pressure relief valve.
Element 12: wherein the pressure relief valve is set to divert a portion of the pressure exerted against the first or second ball valve member when in a closed position to a fluid located within the fluid chamber area through the fluid port.
Element 13: wherein the pressure relief valve is a first pressure relief valve located in a first cavity and uphole from the first ball valve member and further including a second pressure relief valve located within a second cavity formed in the interior diameter wall of the ball housing and downhole from the second ball valve member and wherein the fluid path extends from the fluid port to the first and second pressure relief valves.
Element 14: wherein the first and second pressure relief valves are set to divert a portion of the pressure exerted against the first or second ball valve members when closed positions to a fluid located within the fluid chamber area through the fluid port.
Element 15: further comprising: a travel piston valve located within a cavity formed in an interior diameter wall of the ball housing and uphole or downhole from the fluid chamber area, the travel piston valve having a sealing member thereabout to provide a pressure seal about the travel piston valve; a travel piston valve communication port located in the ball housing that fluidly connects the pressure travel piston valve with the central bore; and a fluid port having a first end that opens into the central bore of the ball housing and a second end that opens into a fluid path that extends from the port to the travel piston valve.
Element 16: wherein the travel piston valve is an assembly that further includes a biasing member located within the cavity that has a biasing constant designed to allow the biasing member to be compressed when a predetermined pressure is exerted against the travel piston valve.
Element 17: wherein the travel piston valve is a first travel piston valve located in a first cavity and uphole of the first ball valve member and further including a second travel piston valve located within a second cavity formed in the interior diameter wall of the ball housing and downhole of the second ball valve member and wherein the fluid path extends from the travel piston valve port to the first and second travel piston valves.
Element 18: wherein the first and second travel piston valves are first and second travel piston valve assemblies that each includes a biasing member located within the first and second cavities and that has a biasing constant that allows the biasing member to be compressed when a predetermined pressure is exerted against the first or second travel piston valves, respectively.
Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.