Patent Application
20130043657
Fluid systems, such as oil and gas exploration, production, and transport systems, typically include multiple segments of tubing, valves, and connectors that are sealed together by various seals. These seals are often subjected to harsh environmental conditions, such as corrosive fluids, extreme pressures, and extreme temperatures. Moreover, seals are often disposed in remote equipment, such as a marine (e.g., subsea) wellhead, which can make access and repair difficult and expensive. In oil and gas applications, seals are typically constructed of a metal or an elastomer. Metal seals provide long-term resistance to well bore fluids, temperatures and pressures, but often rely on high installation forces and complicated design and geometry to provide reliable sealing. Elastomeric seals typically have a simple design and can be installed with low installation forces. Further, elastomeric seals may provide a seal across imperfections (e.g., damage, concentricity and ovalities) on sealing surfaces, and have larger manufacturing tolerances, concentricity and ovality allowances. Elastomeric seals are generally formed from an elastomeric material that is designed for use in a particular environment.
S-seals are elastomeric seals that include over-molded coil springs. In high temperature and high pressure applications, traditional elastomeric seals, such as O-rings may extrude resulting in loss of seal. The over-molded coil springs of the S-seal resist extrusion. Consequently, S-seals may be preferred in applications involving extreme temperature and pressure.
An S-seal for sealing an annulus between a mandrel outer surface and a tubular inner surface. In one embodiment, the S-seal includes a ring comprising a seal face, a gland face, and opposing side faces. The gland face is opposite the seal face. The side faces extend between the seal face and the gland face. A spring is embedded in the ring at each intersection of the seal face with one of the side faces. Each side face comprises a groove disposed between the spring and an intersection of the gland face and the side face.
In another embodiment, a system includes a mandrel, a tubular, and an S-seal. The tubular is disposed about the mandrel. The S-seal includes a sealing face and side faces. One of the mandrel and the tube includes a circumferential channel for retaining the S-seal. The S-seal is disposed in the channel and seals an annulus between the mandrel and the tube. The sealing face seals against one of the tube and the mandrel. The side faces seal against the side walls of the channel.
In yet another embodiment, a seal includes an elastomeric body, metal springs, a first face, a second face, and side faces. The metal springs are embedded in corners of the elastomeric body. The first face extends between the outer corners having the embedded springs. The second face is opposite the first face. The side faces extend between the first face and the second face. Each side face is configured to seal to a gland wall on a radius of the spring.
For a detailed description of exemplary embodiments of the invention, reference will now be made to the accompanying drawings in which:
Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.
In the following 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. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. In addition, as used herein, 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. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis.
The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.
Conventional S-seals are designed to seal on seal faces disposed on the outside and inside diameters of the seal. Embodiments of the present disclosure include an improved S-seal that provides better sealing characteristics than conventional S-seals. Embodiments of the S-seals disclosed herein seal along the side faces of the S-seal and at least one of the faces defined by the outside diameter and the inside diameter of the S-seal.
The mandrel 102 includes an annular channel or seal gland 110 formed in the outer face of the mandrel 102. The S-seal 106 is disposed in the seal gland 110 and compressed between the mandrel 102 and the tubing 104 to seal the annulus 112. In the fluid system 100, the S-seal 106 may be subject to working pressures of up to 20,000 pounds per square inch (PSI) or more. Further, the operating environment of such systems may include temperatures ranging from about −50° Fahrenheit (F.) to over 400° F.
In some embodiments of the fluid system 100, the S-seal is disposed in a seal gland formed in the inner surface of the tubing 104, rather than the seal gland 110 of the mandrel 102. In such embodiments, the various structural features of the S-seal are arranged differently than the features of the seal 106 as will be discussed below.
The body of the S-seal 106 is generally formed of an elastomer, such as nitrile, hydrogenated nitrile butadiene rubber (HNBR), polyether ether ketone (PEEK), thermoplastics, fluroelastomers, perfluroelastomers, perflurosilicons, etc. Selection of a particular elastomer may be based on the pressure, temperature, and chemical environment in which the S-seal 106 is to operate. Coil springs 208 are embedded in the body of the S-seal 106 at the intersection of the sealing face 204 with each side face 206. The coil springs 208 inhibit extrusion of the elastomer when the S-seal 106 is exposed to extreme pressure and/or temperature. The springs 208 may be formed of stainless steel or an alloy of nickel and chromium, such as an INCONEL alloy.
Embodiments of the S-seal 106 are configured to seal along the side walls 302 of the gland 110. Thus, in the S-seal 106, the side faces 206 are sealing faces. Each of the side faces 206 includes a groove or channel 210. The groove 210 may have a semi-circular profile. As the S-seal is compressed between the mandrel 102 and the tubing 104, the groove 210 increases the energy applied to the side face 206 in the area between the groove 210 and the intersection of the side face 206 and the sealing face 204 (i.e., the area between the groove 210 and the corner where the spring 208 is embedded). The increased surface energy applied to the side face 206 forces the side face 206 against the side wall 302 causing the side face 206 to form a robust seal with the side wall 302 of the gland 110. In some embodiments, the groove 210 is disposed to cause the side face 206 to seal with the gland wall 302 along a radius 306 of the spring 208.
Because embodiments of the S-seal 106 seal to the gland wall 302, the manufacturing tolerances of the gland walls 302 used with the S-seal 106 may be relaxed when compared to the tolerances required for use with a conventional S-seal. Thus, the manufacturing costs of devices using the S-seal 106 may be reduced. In some embodiments, the gland walls 302 may be disposed at an acute, rather than a normal, angle from the gland bottom 304.
The sealing face 204 of the S-seal 106 includes a protrusion or projected surface 212. Some embodiments include a groove 214 in the projected surface increases the energy applied to the sealing face 204 when the S-seal is compressed, thereby improving the seal between the sealing face 204 and the inner surface of the tubing 104.
In some embodiments of the S-seal 106, the gland face 202 is a non-sealing face. That is, the gland face 202 is not intended to form a seal with the gland bottom 304. The gland face 202 may lack grooves, such as those included in the side and seal faces.
The body of the S-seal 400 is generally formed of an elastomer, such as nitrile, hydrogenated nitrile butadiene rubber (HNBR), etc. Selection of a particular elastomer may be based on the pressure, temperature, and chemical environment in which the S-seal is to operate. Coil springs 408 are embedded in the body of the S-seal 400 at the intersection of the sealing face 404 with each side face 406. The coil springs 408 inhibit extrusion of the elastomer when the S-seal 400 is exposed to extreme pressure and/or temperature. The springs 408 may be formed of stainless steel or an alloy of nickel and chromium, such as an INCONEL alloy.
Embodiments of the S-seal 406 are configured to seal along the side walls of the gland in which the S-seal 400 is seated. Thus, in the S-seal 400, the side faces 406 are sealing faces. Each of the side faces 406 includes a groove or channel 410. As the S-seal 400 is compressed between the mandrel 102 and the tubing 104, the groove 410 increases the energy applied to the side face 406 in the area between the groove 410 and the intersection of the side face 406 and the sealing face 404 (i.e., the area between the groove 410 and the corner where the spring 408 is embedded). The increased surface energy applied to the side face 406 causes the side face 406 to form a robust seal with the side wall of the gland. In some embodiments, the groove 410 is disposed to cause the side face 406 to seal with the gland wall on a radius of the spring 408.
Because embodiments of the S-seal 400 seal to the gland wall, the manufacturing tolerances of the gland walls used with the S-seal 400 may be relaxed when compared to use with a conventional S-seal. Thereby reducing manufacturing costs. In some embodiments, the gland walls may be disposed at an acute, rather than a normal angle from the gland bottom.
The sealing face 404 of the S-seal 400 includes a protrusion or projected surface 412. A groove 414 in the projected surface increases the energy applied to the sealing face 404 when the S-seal 400 is compressed, thereby improving the seal between the sealing face 404 and the outer surface of the mandrel 102.
In some embodiments of the S-seal 400, the gland face 402 is a non-sealing face. That is, gland face 402 is not intended to form a seal with the gland bottom on which the gland face is seated. The gland face 402 may lack grooves.
The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.
