Patent ID: 8061419
Filing Date: 2011-11-22
Classification: E21B

Abstract:
1. A wellhead connection for connecting and sealing a wellhead onto a casing, the casing having an outer wall and an upper end, the wellhead connection comprising: a generally tubular, pressure-containing upper head housing defining a central bore to accommodate the upper end of the casing, a stop shoulder formed in the central bore, the stop shoulder being configured to allow the upper head housing to rest on the upper end of the casing to support a weight load put on the upper head housing by the wellhead, and the upper head housing forming a seal profile section at the lower end of the central bore below the stop shoulder; a metal seal ring located around the casing in the seal profile section of the upper head housing and being configured so as to be compressed radially inwardly by the seal profile section of the upper head housing to form a metal seal to both the casing and the upper head housing, the metal seal ring being conically tapered on its outside diameter, and being formed with inwardly projecting teeth which bite into the casing as the metal seal ring is radially compressed; the seal profile section of the upper head housing being tapered to provide a conical surface having a taper profile, which at an upper part narrows inwardly so as to be diametrically smaller than the outside diameter of the metal seal ring such that the metal seal ring is radially compressed in the narrower part of the seal profile section; an annular slip housing below the upper head housing, the slip housing providing a slip connector to be positioned around the casing for gripping the outer wall of the casing, the slip connector comprising a plurality of segmented conical shaped slips, each slip having a conical external surface, and an internal circumferential surface formed with grooves or teeth configured to engage, grip and support the casing, the slip housing forming a slip bowl shaped to mate with the conical shaped slips during slip energizing, and the slip housing carrying a slip support member to prevent downward movement of the slips prior to slip energizing; an annular bottom ring between the upper head housing and the slip housing, the bottom ring providing a top connector configured to connect to the upper head housing and a bottom connector configured to connect to the slip housing, the bottom ring providing an extension to the central bore to accommodate the casing, and the bottom ring being configured to support the metal seal ring within the seal profile section against downward vertical movement as the metal seal is being radially compressed, and the bottom ring providing a raised inner circumferential rim adjacent the casing below the metal seal ring to support the metal seal ring within the seal profile section against downward vertical movement during metal seal ring energizing; and a plurality of threaded cap screws between the slip housing and the bottom ring to push upwardly on the bottom ring after slip energizing; such that, connecting the slip housing and the bottom ring with the bottom connector energizes the slips upon upward movement of the slip housing into gripping engagement with the casing and locks the slip housing and the bottom ring around the casing, and thereafter connecting the upper head housing and the bottom ring with the top connector energizes the metal seal ring by radially compressing the metal seal ring against the casing to form the metal seal and brings the stop shoulder to rest on the upper end of the casing.