Patent Application
20200096111
The invention relates generally to fluid sealing assemblies.
Fluid seals are widely used to help prevent fluid leaks in association with piping and related components. Typical fluid seals incorporate a resilient, compressible O-ring and may reside in an annular retaining groove. Fluid seals of this type are often used with sliding sleeve valves to preclude leakage when the sleeve valve is closed. When seals are used in applications where high fluid pressures are present (i.e., piping containing high pressure fluid), the O-ring seals can be unseated from their retaining grooves or even damaged when the seal is unloaded. An example of such a situation is a sliding sleeve valve which, when opened, releases pressurized fluid. Sliding sleeve devices of this type are often used in downhole, hydrocarbon production situations wherein high temperatures and pressures can cause such seals to extrude out of their retaining grooves.
The invention provides sealing assemblies which include an annular resilient and compressible sealing member. In described embodiments, the sealing member may be an elastomeric O-ring. Described sealing assemblies also include a retaining groove within which the sealing member is disposed. In a first described embodiment, the retaining groove has a dovetail cross-sectional shape wherein the interior surface, or base, of the groove is wider than the opening of the groove. According to a second described embodiment, the base of the groove is essentially the same width as the opening of the groove. In this embodiment, the side surfaces of the groove have a V-shape or other shape designed to prevent backup members from exiting the retaining groove.
Backup members are disposed within the groove adjacent the sealing member. Preferably, the one or more backup members are shaped to contact at least one side surface of the groove so that the backup members are retained within the groove when lateral force is applied to the backup members. Each of the backup members presents a groove-contacting side surface which is shaped to be generally complementary to the side surface it adjoins. The backup members become interlocked with the side surfaces when the sealing assembly is loaded or energized.
Preferably also, the back-up members each have a sealing element contacting surface which contacts the sealing element and help to retain it within the groove. Preferably, the sealing element contacting surface is concave or V-shaped to allow portions of the sealing element to expand into when it is compressed.
A sealing element capture gap is defined between the two back-up members. In particular, the sealing element capture gap is defined between the upper portions of the back-up elements which would engage the sealing element to prevent it from exiting the retaining groove. This gap becomes smaller when the sealing assembly is unloaded or de-energized.
The sealing member and backup members are retained within the retaining groove and extrusion of the sealing element from the retaining groove is prevented by the backup members and the configuration of the retaining groove. This is advantageous during high pressure unloading where the seal will be exposed to forces which would tend to unseat it or damage it. Further, the configuration of the backup members will tend to prevent extrusion of the sealing element from the retaining groove over time.
For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings, wherein like reference numerals designate like or similar elements throughout the several figures of the drawings and wherein:
Sealing assemblies constructed in accordance with the present invention can be incorporated into one of two components to be assembled together and provide a fluid seal when so assembled. A sealing assembly in accordance with the present invention can be incorporated into a sliding sleeve assembly.
The sleeve 14 presents a radially outwardly-facing first sealing surface 23, while the mandrel 12 presents a radially inward-facing second sealing surface 25. A sealing assembly 24, in accordance with the present invention, is incorporated into the first sealing surface 23. The sealing assembly 24 will be energized to create fluid sealing when the first sealing surface 20 abut the second sealing surface 25 when the two components 12, 14 are assembled. During operation of the sleeve valve 10, the sealing assemblies 24 will go through various stages of being loaded (i.e., sealing assembly compressed) and unloaded. For example, portions of the sealing assemblies 24 are unloaded as they are moved across an outer radial port 20.
An annular sealing member 40 resides within the retaining groove 26. The sealing member 40 is preferably compressible and resilient. In the depicted embodiment, the sealing member 40 is an elastomeric O-ring. The sealing member 40 is sized such that a portion of the sealing member 40 extends outwardly beyond the opening 34 of the retaining groove 26 when the sealing member 40 is disposed within the retaining groove 26.
At least one backup member is also disposed within the retaining groove 26. In the depicted embodiment, there are two backup members, first backup member 42 and second backup member 44. Each of the back-up members 42, 44 is positioned between the sealing member 40 and one of the side surfaces 30 or 32. In preferred embodiments, the back-up members 42, 44 are substantially rigid and may be formed of metal, ceramic, rigid plastics and the like. It is further preferred that each of the backup members 42, 44 have a split ring or C-ring configuration so that the backup members 42, 44 may be radially expanded and contracted within the groove 26. A split ring configuration will also assist in assembly and repair of the sealing assembly 24.
Each of the backup members 42, 44 presents a sealing element contact surface 46 which will adjoin or be in contact with the sealing element 40 when the sealing assembly 24 is assembled. The sealing element contact surface 46 is intended to largely capture a portion of the sealing element 40 to prevent extrusion of or escape of the sealing element 40 out of the retaining groove 26 during operation. When the sealing assembly 24 is energized to create a seal, the sealing element 40 can expand into the sealing element contact surface 46. In particular preferred embodiments, the sealing element contact surface 46 is concave or substantially V-shaped.
Each of the backup members 42, 44 also presents a groove-contacting side surface 48 which will adjoin and contact one of the side surfaces 30 or 32 during operation. Preferably, the groove-contacting side surfaces 48 are substantially smooth to facilitate their ability to slide upon the respective side surface 30 or 32 it is brought into contact with. In the depicted embodiment, a sealing element capture gap 50 is defined between the upper ends of the back-up members 42, 44.
In operation, the sealing assembly 24 is in the initial, unloaded condition which is illustrated by
The backup members 42′ and 44′ each present a groove contacting side surface 48′ which is shaped to be generally complementary to the side surface 30′ or 32′ which it adjoins. In this instance, the groove contacting side surfaces 48′ are pointed having a point or apex 54. Should the side surfaces 30′, 32′ have other shapes (such as U-shaped or rounded), the groove contacting side surfaces 48′ will likewise, be shaped in a manner which is complementary to them.
Operation of the sealing assembly 52 is similar to operation of the sealing assembly 24 described earlier. As the sealing member 40 is compressed, it expands toward each of the side surfaces 30′, 32′. The point or apex 54 of each of the back-up members 42′; and 44′ will be slid into the recess formed by the V-shape of the side surfaces 30′, 32′. When unloading the sealing assembly 52, both the sealing element 40 and the back-up members 42′ and 44′ are lifted toward the opening 34′ of the retaining groove 26′. The further these elements move out of the retaining groove 26′, the more the back-up members 42′ and 44′ will squeeze the sealing element 40 and trap all three elements within the retaining groove 26′. As a result, the back-up members 42′, 44′ become interlocked with the side surfaces 30′, 32′ of the retaining groove 26′. It is further noted that the backup members 42′ and 44′ also define a sealing element capture gap 50 which becomes larger when the sealing assembly 52 is in a loaded condition and smaller when the sealing assembly 52 is unloaded.
