Patent Application
20100072711
In the hydrocarbon recovery arts, seals are endlessly used to effect working conditions supportive of desired production fluid recovery. In recent years engineering and development dollars have been spent attempting to improve both pressure holding capacity and longevity. One type of seal receiving significant interest is a metal-to-metal seal due to the fact that of many types metal seals exhibit high temperature tolerance, high-pressure capability, robust chemical resistance, and high durability.
While a good metal to metal seal is extremely durable and desirable, downhole conditions including mud, chemicals, frequent pressure reversals and corrosion of base structures, and geometric inconsistency of base structures against which a seal is intended to be set can make the attainment of a good contact pattern difficult.
A seal including a seal body having a bridge, a leg extending from the bridge, a gauge ring in operable communication the seal body to cause axial compression thereof, thereby causing the bridge diameter to change, and a seal interface disposed at the seal body. The seal interface including a relatively harder material and a relatively softer material positioned so that the relatively harder material is disposed between the seal body and the relatively softer material.
A method for making a seal comprising disposing a relatively harder material of a seal interface at an anticipated seal contact area on a seal body. Disposing a relatively softer material of a seal interface at the relatively harder material and radially closer to a surface against which the seal is intended to seal when in use.
A method for sealing an annular geometry including activating a seal body to bridge an extrusion gap between a position of the seal body prior to activation and a surface against which the seal is intended to seal. Urging a relatively harder material with the seal body through a relatively softer material and into contact with the surface against which the seal is to seal.
A seal interface including a relatively harder material, a relatively softer material disposed adjacent the relatively harder material such that the relatively softer material is placeable between the relatively harder material, and a surface against which a seal is desired when in use.
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
Referring to
To provide a greater understanding of the function of the seal interface 10 described structurally above, a high level description of one possible seal structure is provided hereunder. Referring to
Also visible in
In operation the exemplary seal 100, due to the shape of body 112, upon axial shortening thereof, will necessarily bulge outwardly. Continued outward bulging into contact with another structure develops a teardrop shape more fully discussed in U.S. application Ser. No. [bao-0188C], which is incorporated herein by reference.
As the seal 100 bulges outwardly (could be configured to bulge inwardly to seal against an inwardly positioned mandrel), interface 10 is moved toward and ultimately into contact with a surface 140 against which the seal 100 is intended to seal. Once contact occurs, the soft material 14 is urged against surface 140 and into any smaller imperfections in that surface 140. This is followed by the material 12 being urged into contact with the surface 140 through the material 14. Ridges 16 operate at this point to cut through the material 14 until they sever a series of annular rings of soft material 14 each one existing within a groove 18. The ridges 16 are at this point in loaded contact with the surface 140. It is to be appreciated that for each two consecutive ridges that are in contact with the surface 140, a ring of soft material 14 is captured by material 12 defining the respective groove and a portion of the surface 140 extending between the consecutive ridges 16. This soft material then is prevented from being squeezed out of the seal area and thus the purpose it serves, to fill small imperfection in the surface 140 remains served for the life of the seal 100. In one embodiment the seal interface 10 is configured such that a minimum of three ridges 16 remain in contact with the surface 140 when the seal is set thereby ensuring a minimum of two annular rings of the softer material 14are trapped in compressive contact with two consecutive grooves 18 and the surface 140. It is to be appreciated that the seal 100 employs sequential material hardness in its construction. Seal body 112 is the hardest of the mobile sealing portions of seal 100; material 12 is next hardest and material 14 is least hardest. This is beneficial in that the seal body 112 is thus able to bridge an extrusion gap 142, material 12 is able to bridge casing eccentricities and material 14 is able to seal corrosion defects.
While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.
