Sealing apparatus for high pressure high temperature (HPHT) applications

A method of sealing an annular space between first and second concentrically disposed members, the method comprising:

• positioning a monolithic sealing ring having a convexly-shaped radial cross section within the annular space between the first and second concentrically disposed members, the monolithic sealing ring comprising:
• oppositely inclined interior and exterior surfaces each having a generally frusto-conical shape and defining opposing first and second edges, the convexly-shaped radial cross section of the monolithic sealing ring having a first width measured between the respective first edges of the interior and exterior surfaces and a second width measured between the respective second edges of the interior and exterior surfaces, the first width being smaller than the second width;
• a nose, comprising:
• a first portion having a first radius of curvature, which first portion forms a first convex surface;
• and
• opposing second and third portions adjoining the respective first edges of the interior and exterior surfaces;
• and
• a second convex surface adjoining the respective second edges of the interior and exterior surfaces opposite the nose;
• positioning a compression ring within the annular space on one side of, and directly adjacent to, the monolithic sealing ring, the compression ring defining a planar first surface adapted to engage the second convex surface of the monolithic sealing ring;
• positioning a back-up ring within the annular space on another side of, and directly adjacent to, the monolithic sealing ring, the back-up ring defining a concave second surface adapted to be engaged by the first portion of the nose, the concave second surface having a second radius of curvature that is greater than the first radius of curvature;
• and
• actuating the monolithic sealing ring, the compression ring, and the back-up ring from a first configuration to a second configuration to seal the annular space between the first and second concentrically disposed members, wherein, in the first configuration:
• the planar first surface of the compression ring engages the second convex surface of the monolithic sealing ring;
• the first portion of the nose engages the concave second surface of the back-up ring;
• the compression ring is spaced apart from the back-up ring by a first distance;
• at least respective portions of the interior and exterior surfaces are disengaged from the first and second concentrically disposed members, respectively;
• and
• the opposing second and third portions of the nose are disengaged from the concave second surface of the back-up ring;
• wherein, in the second configuration:
• the planar first surface of the compression ring engages the second convex surface of the monolithic sealing ring;
• the first portion of the nose engages the concave second surface of the back-up ring;
• the compression ring is spaced apart from the back-up ring by a second distance that is less than the first distance;
• the at least respective portions of the interior and exterior surfaces of the monolithic sealing ring engage the first and second concentrically disposed members, respectively;
• and
• the opposing second and third portions of the nose engage the concave second surface of the back-up ring;
• and
• wherein actuating the monolithic sealing ring, the compression ring, and the back-up ring from the first configuration to the second configuration comprises communicating a fluid pressure to the annular space on the one side of the monolithic sealing ring.