Patent Application
20120031624
This section provides background information to facilitate a better understanding of the various aspects of the present invention. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
The present disclosure relates generally to wellbore operations and equipment and more specifically to subsurface valves and engaging members (e.g., flow tubes, sleeves) that can be utilized to open and/or close the valve.
Equipment is utilized in wells (e.g., wellbore, bore hole) to facilitate the flow of fluids in the well relative to the subterranean formation surrounding the well. Valves are utilized in the well (e.g., subsurface) to inhibit or otherwise control the fluid flow through the well equipment. For example, subsurface safety valves are often disposed in the well to prevent or limit the flow of fluids in an undesired direction. For example, flapper valves are often utilized to enable flow of fluid in a first direction while blocking fluid flow in the opposite second direction.
For example, many subsurface safety valves utilize a flapper as a closure mechanism fitted within a body or housing to enable control over fluid flow through a primary longitudinal bore upon an appropriate applied signal (e.g., pressure, flow, electrical or other means) from a control system. The applied signal is commonly a rapid reduction of the hydraulic operating pressure that holds the valve open, thereby facilitating shut-in of the production or injection fluid flow by closure of the valve. The closure mechanism typically is movable between the open and closed position by movement of a tubular device, often called a flow tube. The flow tube can be moved to the open position or operated by the valve actuator which is motivated by hydraulics, pressure, electronic, or other applied signals and power sources. The shifting of the flow tube to a closed position can be performed for example by a mechanical power spring and/or a pressurized accumulator that applies a required load to move the flow tube to the closed position upon interruption of the “opening” signal. As a result, the valve can be required to close against a moving flow stream. Fluid forces acting on the closure member can result in damage to the flow tube and thus to the valve. Further, impacts from the closure member against the end of the flow tube can deform or gall the flow tube leading to failure to operate the valve when needed.
According to one or more aspects of the present disclosure, an engaging member for operating a subsurface valve between an open position and a closed position includes a bottom portion comprising a terminal end adapted for contacting a valve closure member, the bottom portion having a first material characteristic; and an upper portion having a second material characteristic that is quantitatively different from the first material characteristic. In some embodiments the material characteristic includes strength and the first material characteristic is greater than the second material characteristic.
According to one or more aspects of the present disclosure a subsurface valve configured to move between an open position and a closed position in response to an applied signal includes a housing having a bore; a closure member disposed with the housing; a flow tube movably disposed in the housing, the flow tube comprising a terminal end positioned to contact the closure member, wherein the closure member is actuated to the open position in response to a certain force applied to the flow tube and actuated to the closed position upon relief of the certain applied force; and a bottom portion of the flow tube proximate the terminal end comprising a first material characteristic that is and the second characteristic differ different than a second material characteristic of an upper portion of the flow tube.
A method, according to one or more aspects of the present disclosure, for operating a subsurface valve includes disposing a valve in a wellbore, the valve including a housing having a bore, a closure member disposed with the housing, a flow tube movably disposed in the housing, the flow tube comprising a terminal end positioned to contact the closure member and a bottom portion of the flow tube proximate the terminal end having a first material characteristic that is quantitatively different than a second strength characteristic of an upper portion of the flow tube; moving the closure member to an open position in response to a certain force being applied to the flow tube; and moving the closure member to an open position in response to releasing at least a portion of the certain force applied to the flow tube.
The foregoing has outlined some of the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.
The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact.
As used herein, the terms “up” and “down”; “upper” and “lower”; “top” and “bottom”; and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements. Commonly, these terms relate to a reference point as the surface from which drilling operations are initiated as being the top point and the total depth of the well being the lowest point, wherein the well (e.g., wellbore, borehole) is vertical, horizontal or slanted relative to the surface. The terms “pipe,” “tubular,” “tubular member,” “casing,” “liner,” “tubing,” “drill pipe,” “drill string” and other like terms can be used interchangeably. The terms may be used in combination with “joint” to mean a single unitary length; a “stand” to mean one or more, and typically two or three, interconnected joints; or a “string” meaning two or more interconnected joints.
In this disclosure, “hydraulically coupled” or “hydraulically connected” and similar terms (e.g., fluidic, pneumatic), may be used to describe bodies that are connected in such a way that fluid pressure may be transmitted between and among the connected items. The term “in fluid communication” is used to describe bodies that are connected in such a way that fluid can flow between and among the connected items. It is noted that hydraulically coupled may include certain arrangements where fluid may not flow between the items, but the fluid pressure may nonetheless be transmitted. Thus, fluid communication is a subset of hydraulically coupled.
It is common to use subsurface valves in wells to control fluid flow through the wellbore. The subsurface valves are commonly actuated to a first position (e.g., open) by the application of hydraulic pressure, for example from the surface, and biased to the second position (e.g., closed) by a biasing mechanism (e.g., stored energy assembly), such as an enclosed pressurized fluid chamber or a mechanical spring. The fluidic pressure may be applied to a piston and cylinder assembly, for example, that acts against the biasing force of the biasing mechanism to open and hold the safety valve opened. The biasing force acts on the piston to move a flow tube to a position allowing the closure member of the valve close to move to the closed position when the fluid pressure is reduced below a certain value. Examples of some subsurface safety valves are disclosed in U.S. Pat. Nos. 4,161,219 and 4,660,646 and U.S. Patent Application Publications 2009/0266555, 2010/0006295 and 2010/0139923, which are all incorporated herein by reference.
Hydraulic pressure is provided through control line 28 to subsurface safety valve 12 actuating valve closure member 30 to the open position allowing fluid to flow across subsurface safety valve 12 within tubular string 22. Hydraulic pressure is maintained above a certain level to hold valve closure member 30 in the open position. To actuate subsurface safety valve 12 to the closed position, as shown in
To open subsurface safety valve 12, as illustrated in
To close subsurface safety valve 12, for example due to a pressure kick in the well, the hydraulic pressure can be relieved from control line 28 to a level such that biasing mechanism 40 moves flow tube 36 permitting valve closure member 30 to close. It is often desired for valve 12 to respond quickly to a close signal. As a result, closure member 30 can slam against flow tube 36, in particular contact end 44.
As further described below, flow tube 36 comprises a bottom portion 48 that includes contact end 44 and that has a material characteristic that quantitatively differs from the same material characteristic of upper portion 50 of flow tube 36. The material characteristics may include, without limitation, one or more of strength, elasticity (e.g., modulus of elasticity), flexibility, coefficient of friction (e.g., resistance to fluid flow), anti-galling, and the like. For example, the bottom portion 48 can be constructed to be more resistant to deformation and/or galling relative to upper portion 50. Bottom portion 48 may have a first material characteristics that has a lower coefficient of friction and reduces the resistance to the flow of fluid and debris relative to top portion 50. In some embodiments, bottom portion 48 may be more flexible and/or have a greater yield strength than upper portion 50. In some embodiments bottom portion 48 can have a strength greater than the upper portion 50 and in other embodiment bottom portion 48 can have a strength less than or the same as upper portion 50.
In some embodiments, bottom portion 48 is a separate piece of material connected with the upper portion 50 for example by welding, bonding and threading. In other embodiments, bottom portion 48 may be continuous portion of flow tuber 36 with upper portion 50. The material of construction of bottom portion 48 may be the same or different than that material of construction of upper portion 50. The different material characteristic of bottom portion 48 from upper portion 50 may be achieved by the material of construction, the manner of construction, and/or inclusion a material characteristic changing element (e.g., substance). For example, a layer of material may be disposed with on a surface of bottom portion 48. The characteristic changing element or material may be disposed with bottom portion 48, by coating, deposition, or attachment (e.g., bonding, welding, etc.) as a layer of material. For example, bottom portion 48 can be a section of flow tube 36 that comprises a layer of material or the like that has a material characteristic such as higher strength than that of the upper portion 50. For example, bottom portion 48 may comprise a layer or strip of material on the inner surface 52 and/or exterior surface 54 (
In the depicted embodiment, bottom portion 48 is a unitary piece that is connected to upper portion 50 via a connection 58. Connection 58 may be by any manner suitable for connecting the opposing pieces, for example threading, bonding and welding. Connection 58 is depicted in
Bottom portion 48 and upper portion 50 are depicted in
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure. The scope of the invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. The terms “a,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded.
