Patent Application
20110203801
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion in this section.
In a variety of downhole applications, flow isolation valves are used to isolate formations for reasons related to prevention of fluid loss, underbalanced well control, lubricator valve applications, and other reasons that benefit from the ability to isolate regions along a wellbore. The flow isolation valve may be a ball valve designed to provide a bidirectional pressure seal. The ball valve is moved from an open flow position to a closed position by passing a shifting tool through its center. Typically, a shifting tool is attached below perforating guns on a gun string such that when the perforating guns are pulled out of hole, the shifting tool shifts the ball of the formation isolation valve to a closed position. Once closed, the well head pressure may be safely bled off while the subject formation remains isolated. This allows the well to be suspended for days or even months.
However, the ball of the formation isolation valve also creates a barrier onto which debris is often deposited. The debris can clog the mechanism and ultimately prevent the shifting tool from dislodging the debris during efforts to open the ball. Additionally, existing ball designs employ parts that are difficult to manufacture due to dimensional instability and tight tolerance requirements. The tight tolerances and the complex designs are employed to achieve both rotation and translation of the ball within the ball valve structure. Because of the difficult design requirements, many of the parts manufactured for construction of the ball valves are scrapped, and that leads to additional expense and inefficiency.
In general, embodiments of the present disclosure comprise a system and methodology for providing a formation isolation valve that utilizes a ball rotatably mounted within a valve housing. The valve is designed to enable rotation of the ball about a fixed axis without translation of the ball. Rotation of the ball is achieved by connecting an arm to the ball at a position offset from the axis of rotation. A movable mandrel also is connected to the arm to enable selective actuation of the ball.
Other or alternative features will become apparent from the following description, from the drawings, and from the claims.
Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying drawings illustrate only the various implementations described herein and are not meant to limit the scope of various described technologies. The drawings are as follows:
In the following description, numerous details are set forth to provide an understanding of the present disclosure. However, it will be understood by those of ordinary skill in the art that embodiments of the present disclosure may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. In the specification and appended claims: the terms “connect”, “connection”, “connected”, “in connection with”, “connecting”, “couple”, “coupled”, “coupled with”, and “coupling” are used to mean “in direct connection with” or “in connection with via another element”; and the term “set” is used to mean “one element” or “more than one element”. As used herein, the terms “up” and “down”, “upper” and “lower”, “upwardly” and downwardly”, “upstream” and “downstream”; “above” and “below”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the disclosure.
Embodiments of the present disclosure generally relate to a flow isolation valve system having a design that is simpler to manufacture and more dependable to use in a well application. The design utilizes simple, strong features that enable dependable actuation of a ball type flow isolation valve. Additionally, the component design enables manufacture with minimal material removal and less dimensional movement. The design also enables ample manufacturing tolerances because of the placement of various functional features on easy to machine pieces, such as inserts used to hold ball trunnions on which the ball of the valve is rotatably mounted. As a result, the tolerances for larger, more difficult parts within the overall assembly may be relaxed.
In one illustrative embodiment, the design of the formation isolation valve employs relatively large yolk arms that are configured to provide great strength. The yoke arms enable employment of large forces to open the ball in the event the ball becomes jammed or stuck with debris. In another embodiment, the yoke arms are replaced by rods that can be used to manipulate the ball between closed and open flow positions. In any of the embodiments, the design of the formation isolation valve also enables use of a full ball instead of a half ball and that allows for the addition of other functional features. For example, a full ball allows the use of a wiper on one side of the ball (e.g., typically at the top of the ball, nearest to the surface) to reduce debris otherwise interfering with the ball. The use of a wiper reduces the potential for jamming the ball or for incurring other interference with ball operation.
Referring generally to
Depending on the specific well application, e.g. such as a well perforation application, the completion/well equipment 26 is delivered downhole via a suitable conveyance 36. However, the conveyance 36 and the components of completion 26 often vary substantially. In many applications, one or more packers 38 is used to isolate the annulus between downhole equipment 26 and the surrounding wellbore wall, which may be in the form of a liner or casing 40. The formation isolation valve 24 may be selectively actuated to open or isolate formation 30 with respect to flow of fluid through completion 26.
Referring generally to
A full ball 42 may generally be configured as a spherically shaped valve component intersected by a cylindrically shaped flow passage. This configuration results in two essentially symmetrical and semi-spherical portions of the ball 42 being respectively exposed to the upstream and downstream environments across the fixed axis 50 when the ball 42 is in a closed position. However, some embodiments may use a half ball (not shown), such as the half ball applications described in U.S. Pat. No. 6,401,826, to Patel, the contents of which are hereby incorporated by referenced in their entirety. A half ball is not necessarily symmetrical across fixed axis 50 in a closed position. Instead, a half ball may respectively expose only the upper and lower surfaces of a single semi-spherical portion to the upstream and downstream environments in a closed position.
In the embodiment illustrated in
In the example illustrated, the yoke arm 60 is attached to a movable mandrel 70 at its actuation end 64. The construction enables adjustments to be made with respect to movement of arm 60 and/or the attachment of arm 60 to mandrel 70 for compensation of manufacturing tolerances. The movable mandrel 70 is simply moved in a linear direction through valve housing 58 to cause arm 60 to rotate ball 42 between open and closed positions. Accordingly, the ball 42 is actuated by pivoting the ball on its trunnions 46 without significant or, in some cases, any translation of the ball. In one specific example, the pivoting motion is caused by linear motion of arm 60/engagement end 62 which passes through slot 68 in ball 42 and contacts a face 72 to cause rotation of the ball. This type of actuation renders ball 42 and the cooperating components less sensitive to debris because the ball itself does not have to translate but rather simply rotates in place.
Movable mandrel 70 may be constructed in a variety of configurations for imparting linear movement to arm 60. In some applications, mandrel 70 may comprise a tubular member located within valve housing 58 for lineal movement along an interior of upper cage 54 (see, for example,
In
Additionally, a wiper 80 may be deployed against ball 42 to wipe the ball of debris as it is rotated and to thereby reduce the chance of debris preventing rotation of the ball. In the example illustrated, wiper 80 is a ring disposed on a side of ball 42 generally opposite seal retainer 76. The seal 74 and wiper 80 cooperate to facilitate dependable and repeatable motion of ball 42 as an interior flow passage 82 is transitioned between an open flow configuration (as illustrated in
The wiper 80 may be formed from a variety of materials. For example, the wiper may be formed from polyetheretherketone (PEEK), brass, aluminum bronze, or other suitable materials. Additionally, the wiper 80 may be spring-loaded via an elastomeric material, a mechanical spring, or another suitable biasing member. The wiper 80 also may be formed as another seal to aid in preventing debris from entering the area surrounding ball 42. Prevention of debris accumulation also may be facilitated with a ball section filler 86 deployed in otherwise empty space located between ball 42 and the surrounding valve housing 58. By way of example, filler 86 may be formed from PEEK or another suitable material. The containment provided by seal 74 and wiper 80 enable arm or arms 60 to translate in an area generally sealed off from wellbore debris. It also should be noted that the locations of seal 74 and wiper 80 may be interchanged or otherwise altered to facilitate prevention of debris accumulation.
Referring generally to
By way of example, slider mechanism 92 connects the corresponding rod 88 to ball 42 at a position offset from the rotational axis 50. The slider mechanism 92 may be designed to provide pivotable engagement between rod 88 and ball 42 to enable rotational movement of ball 42 when mandrel 70 moves in a linear direction to drive connection mechanism 90. In this example, the rod 88 is able to pivot at both slider mechanism 92 and at connection mechanism 90 in order to accommodate rotation of ball 42. As illustrated in
Well system 20 (
Also, the formation isolation valve 24 may be designed from a variety of materials and in a variety of sizes and configurations. The isolation valve 22 (
Elements of the embodiments have been introduced with either the articles “a” or “an.” The articles are intended to mean that there are one or more of the elements. The terms “including” and “having” are intended to be inclusive such that there may be additional elements other than the elements listed. The term “or” when used with a list of at least two elements is intended to mean any element or combination of elements.
Although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Accordingly, such modifications are intended to be included within the scope of this invention as defined in the claims.
