Downhole assembly for selectively sealing off a wellbore

Abstract

Downhole assemblies and methods for isolating a wellbore. A downhole tool can include a body having a bore or flowpath formed therethrough, and one or more sealing members disposed therein. The one or more sealing members can include an annular base and a curved surface having an upper face and a lower face, wherein one or more first radii define the upper face, and one or more second radii define the lower face, and wherein, at any point on the curved surface, the first radius is greater than the second radius. The sealing members can be disposed within the bore of the tool using one or more annular sealing devices disposed about the one or more sealing members.

What is claimed is: 
     
         1 . An assembly for sealing off a bore of a downhole tool, comprising:
 a curved surface composed of a ceramic material and comprising an outer face and an inner face, wherein the outer face has a convex configuration and the inner face has a concave configuration, the outer face and the inner face of the curved surface having a distance therebetween;   an annular base depending from the curved surface, the annular base comprising a cylindrical inner surface and a cylindrical outer surface having a distance therebetween;   wherein the outer face of the curved surface comprises an apex relative to the annular base and a radius at the apex, the outer surface of the annular base has a diameter, and the radius of the outer face of the curved surface is 0.5 times to 2.0 times the diameter of the outer surface of the annular base; and   a first circular seal contacting an exterior surface of the annular base, the first seal configured to form a fluid barrier between at least the annular base and the first seal when the assembly is mounted in a downhole tool.   
     
     
         2 . The assembly of  claim 1 , further comprising a second seal disposed about the outer face of the curved surface, wherein the first seal is an O-ring, and the second seal is a crush seal. 
     
     
         3 . The assembly of  claim 1 , wherein the outer face of the curved surface comprises a perimeter where the convex configuration ends and a distance between opposing sides of the perimeter, and the diameter of the outer surface of the annular base corresponds to the distance between opposing sides of the perimeter such that the annular base is within a perpendicular projection of the perimeter of the curved surface. 
     
     
         4 . The assembly of  claim 1 , wherein the distance between the cylindrical inner surface and the cylindrical outer surface of the annular base corresponds to the distance between the outer face and the inner face of the curved surface. 
     
     
         5 . The assembly of  claim 1 , wherein the curved surface and the annular base are an integral unit composed of the same material. 
     
     
         6 . The assembly of  claim 1 , further comprising a second seal disposed about the annular base. 
     
     
         7 . The assembly of  claim 1 , wherein the outer surface of the annular base comprises a first end proximal the curved surface, a second end distal from the curved surface, and a height between the first end and the second end, and the height of the outer surface of the annular base is less than the radius of the outer face of the curved surface. 
     
     
         8 . The assembly of  claim 1 , wherein the outer surface of the annular base comprises a first end proximal the curved surface, a second end distal from the curved surface, and a height between the first end and the second end, the outer face of the curved surface comprises a height at the apex relative to first end of the annular base, the height of the outer surface of the annular base being less than the height of the outer face of curved surface. 
     
     
         9 . The assembly of  claim 1 , wherein the outer surface of the annular base comprises a first end proximal the curved surface, a second end distal from the curved surface, and a height between the first end and the second end, and the inner face of the curved surface comprises a height at the apex relative to the first end of the annular base, the height of the outer surface of the annular base being less than the height of the inner face of curved surface. 
     
     
         10 . The assembly of  claim 1 , wherein the first seal is located adjacent a portion of the annular base distal from the curved surface. 
     
     
         11 . The assembly of  claim 10 , wherein the first seal is compressed by the exterior surface of the annular base and an inner wall of the downhole tool when the assembly is mounted in the downhole tool. 
     
     
         12 . The assembly of  claim 11 , wherein the first seal is held in place by a groove. 
     
     
         13 . The assembly of  claim 1 , wherein the first seal is compressed by the exterior surface of the annular base and an inner wall of the downhole tool when the assembly is mounted in the downhole tool. 
     
     
         14 . The assembly of  claim 1 , wherein the annular base comprises a first end proximal the curved surface and a second end distal from the curved surface, and the first seal is located nearer the first end of the annular base. 
     
     
         15 . The assembly of  claim 14 , wherein the first seal is compressed by the exterior surface of the annular base and an inner wall of the downhole tool when the assembly is mounted in the downhole tool. 
     
     
         16 . The assembly of  claim 15 , wherein the first seal is held in place by a groove. 
     
     
         17 . The assembly of  claim 1 , wherein the outer surface of the annular base has a first end proximal the curved surface, a second end distal from the curved surface, and a height between the first end and the second end, and the outer face of the curved surface has an apex relative to the annular base and a radius at the apex, the radius having its origin located between the first end and the second end of the annular base. 
     
     
         18 . An assembly for sealing off a bore of a downhole tool, comprising:
 a curved surface composed of a ceramic material and comprising an outer face and an inner face, wherein the outer face has a convex configuration and the inner face has a concave configuration, the outer face and the inner face of the curved surface having a distance therebetween;   an annular base depending from the curved surface, the annular base comprising a cylindrical inner surface and a cylindrical outer surface having a distance therebetween;   a first circular seal contacting an exterior surface of the annular base, the first seal configured to form a fluid barrier between at least the annular base and the first seal when the assembly is mounted in a downhole tool.   
     
     
         19 . An assembly for sealing off a bore of a downhole tool, comprising:
 a curved surface composed of a ceramic material and comprising an outer face and an inner face, wherein the outer face has a convex configuration and the inner face has a concave configuration, the outer face and the inner face of the curved surface having a distance therebetween;   an annular base composed of the same material as the curved surface and depending from the curved surface, the annular base comprising a cylindrical inner surface and a cylindrical outer surface having a distance therebetween;   wherein the outer face of the curved surface comprises an apex relative to the annular base and a radius at the apex, the outer surface of the annular base has a diameter, and the radius of the outer face of the curved surface is 0.5 times to 2.0 times the diameter of the outer surface of the annular base;   wherein the outer face of the curved surface comprises a perimeter where the convex configuration ends and a distance between opposing sides of the perimeter, and the diameter of the outer surface of the annular base corresponds to the distance between opposing sides of the perimeter such that the annular base is within a perpendicular projection of the perimeter of the curved surface;   wherein the outer surface of the annular base comprises a first end proximal the curved surface, a second end distal from the curved surface, and a height between the first end and the second end, and the height of the outer surface of the annular base is less than the radius of the outer face of the curved surface; and   a first circular seal contacting an exterior surface of the annular base, the first seal being an O-ring and configured to form a fluid barrier between at least the annular base and the first seal when the assembly is mounted in a downhole tool.