Patent Application
20180016868
This section provides background information to facilitate a better understanding of the various aspects of the disclosure. 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 actuation devices for downhole tools (e.g., subsurface tools, wellbore tools) and methods of operation.
Hydrocarbon fluids such as oil and natural gas are produced from subterranean geologic formations, referred to as reservoirs, by drilling wells that penetrate the hydrocarbon-bearing formations. Once a wellbore is drilled, various forms of well completion components may be installed in order to control and enhance the efficiency of producing fluids from the reservoir and/or injecting fluid into the reservoir and/or other geological formations penetrated by the wellbore. In some wells, for example, valves are actuated between open and closed states to compensate or balance fluid flow across multiple zones in the wellbore. In other wells, an isolation valve may be actuated to a closed position to shut in or suspend a well for a period of time and then opened when desired. Often a well will include a subsurface valve to prevent or limit the flow of fluids in an undesired direction.
An example of a device includes a hard seat having an axial bore extending along a central axis, a flapper pivotally connected with the hard seat at a hinge axis and pivotal between an open position to allow flow through the bore and a closed position to block flow through the bore, the flapper having a flapper sealing surface that slopes inward toward the central axis along a full circumference of the flapper sealing surface and the hard seat having a hard sealing surface that slopes inward toward the central axis conforming to the flapper sealing surface and on which the flapper sealing surface bears when in the closed position. In accordance to an embodiment the flapper sealing surface is defined between a bottom intersection of a revolve seat line with the bottom and a side intersection of the revolve seat line and the side, wherein the revolve seat line is revolved about a revolve axis.
A method includes forming a flapper sealing surface on a flapper to mate with a hard sealing surface on a hard seat having an internal diameter and an axial bore, wherein the flapper sealing surface slopes inward toward a central axis of the bore along a full circumference of the flapper sealing surface. The inward sloping flapper sealing surface may be defined between a bottom intersection of a revolve seat line with a bottom surface of the flapper and a side intersection of the revolve seat line and a side of the flapper, the revolve seat line being revolved about a revolve axis.
A well system includes a valve disposed with a tubular string and deployed downhole in a wellbore, the valve including a hard seat having an axial bore extending along a central axis, a flapper pivotally connected with the hard seat at a hinge axis and pivotal between an open position to allow flow through the bore and a closed position to block flow through the bore, the flapper having a flapper sealing surface that slopes inward toward the central axis along the full circumference of the flapper sealing surface and the hard seat having a hard sealing surface that slopes inward toward the central axis conforming to the flapper sealing surface and on which the flapper sealing surface bears when in the closed position.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of claimed subject matter.
The 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 disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the 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.
As used herein, the terms connect, connection, connected, in connection with, and connecting may be used to mean in direct connection with or in connection with via one or more elements. Similarly, the terms couple, coupling, coupled, coupled together, and coupled with may be used to mean directly coupled together or coupled together via one or more elements. Terms such as up, down, top and bottom and other like terms indicating relative positions to a given point or element may be utilized to more clearly describe some elements. Commonly, these terms relate to a reference point such as the surface from which drilling operations are initiated.
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 (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 valve opened. The biasing force acts on the piston to move it to a position allowing the closure member to move to the closed position when the actuating fluid pressure is reduced below a certain value. Examples of some subsurface 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.
Depicted valve 12 is operated in this example to an open position in response to a signal (e.g., electric signal, fluidic signal, electro-fluidic signal, mechanical signal) provided via control system 24. Depicted control system 24 includes a power source 26 operationally connected to actuator apparatus 14 to operate a flapper 30 (i.e., closure member) from the one position to another position. In
The hard sealing surface 40 forms an undulating perimeter around the axial bore 36 to conform to the undulating perimeter of the curved flapper. The hard sealing surface 40 includes crests 44 and valleys 46. As noted above, the sealing surfaces 40, 42 slope inward toward the central axis 34 such that the flapper may be self-centering when in the closed position and the seal is reinforced by the pressure acting in the direction from the high pressure side of the closed flapper to the low pressure side (e.g., in the direction of fluid 2 of
The seat line for the hard and flapper sealing surfaces 40, 42 may be calculated, as further described with reference in particular to
Flapper 30 has a back surface 52, bottom surface 54, a side 56 and the flapper sealing surface 42 located for example between the bottom intersection 58 of the revolve seat line 50 and the bottom 54 and the side intersection 60 of the revolve seat line 50 and the side 56. The bottom intersection 58 may be the inner periphery of the flapper sealing surface and the side intersection 60 being the outer periphery. The hard sealing surface 40 corresponds to the flapper sealing surface 42. The line 62 in
The flapper, flapper sealing surface, hard seat and hard seat sealing surface can be formed for example and without limitation by using wire electrical discharge machining process, a ram or plunge machining process, by milling, or by other processes and/or combination of process. After forming of the sealing surfaces according to the revolve seat line the sealing surfaces may be lapped. For example, the flapper may be positioned with the hard seat and the respective sealing surfaces in contact and the flapper rotated or reciprocally rocked relative to the rotational axis of the revolved seat line thereby rubbing the sealing surfaces together. In some instances the respective sealing surfaces may be machine lapped. The rotational axis may be along an axis normal to the hinge axis of the flapper or parallel with the hinge axis. In some instances the surfaces may be lapped. The flapper is then pivotally connected with the hard seat to pivot between an open and a closed position.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the disclosure. Those skilled in the art should appreciate that they may readily use the 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 disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the 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.
