Abstract: A subsea wellhead assembly includes a wellhead body which disposed to support an isolation sleeve for a production tree and to support below the isolation sleeve a production casing hanger for a production casing string. The body also supports a second casing string outside the production casing string whereby to form an annulus between the casing strings. The body includes a passageway which is in communication with the annulus near a lower end of the body and extends upwardly within the wall of the body towards the upper end of the body. A valve is accommodated in the upper part of the body and provides controlled communication between the passageway and a port which can be coupled to the isolation sleeve. The valve is controllable from a production tree in particular is moveable between an open position and a closed position in response to fluid pressure applied to the valve from a production tree by way of the isolation sleeve.

Abstract: Apparatus for the insertion of a pack-off into a recess in a bore of a wellhead body includes an activating sleeve which has a portion disposed for engagement with the pack-off for the movement of the pack-off into the recess and body portions shaped for location on a datum member within the bore. The activating sleeve includes a plurality of apertures circumferentially spaced about the activating sleeve. A running tool which is adapted to move the activating sleeve into engagement with the pack-off carries spring-loaded dogs each disposed in one of the apertures. Each of a plurality of releasing pins is positioned such that it enters a respective one of the apertures when the activating sleeve has caused the pack-off to be located in the recess. The entry of the pins into the apertures causes depression of the dogs out of the apertures and allows the consequent release of the activating sleeve from the running tool.

Abstract: A subsea wellhead a generally cylindrical body including a lower extension for forming an annular space for a cement column between the lower extension and an outer conductor. The extension carries a multiplicity of interfitting rings forming a sleeve which facilitates flexure of the extension in the presence of the cement column. Each ring may comprise an inner flange for disposition adjacent the outside of the extension and an outer flange for fitment over the inner flange of an adjacent ring. The outer flange may have a radial through-bore.

Abstract: Apparatus for the insertion of a pack-off into a recess in a bore of a wellhead body comprises an activating sleeve which has a portion disposed for engagement with the pack-off for the movement of the pack-off into the recess and body portions shaped for location on a datum member within the bore. The activating sleeve includes a plurality of apertures circumferentially spaced about the activating sleeve. A running tool which is adapted to move said activating sleeve into engagement with the packoff carries spring-loaded dogs each disposed in one of the apertures. Each of a plurality of releasing pins is positioned such that it enters a respective one of the apertures when the activating sleeve has caused the packoff to be located in the recess. The entry of the pins into the apertures causes depression of the dogs out of the apertures and allows the consequent release of the activating sleeve from the running tool.

Abstract: A subsea wellhead comprises a generally cylindrical body including a lower extension for forming an annular space for a cement column between the lower extension and an outer conductor. The extension carries a multiplicity of interfitting rings forming a sleeve which facilitates the flexure of the extension in the presence of the cement column. Each ring may comprise an inner flange for disposition adjacent the outside of the extension and an outer flange for fitment over the inner flange of an adjacent ring. The outer flange may have a radial through-bore.

Abstract: A subsea wellhead assembly includes a wellhead body which disposed to support an isolation sleeve for a production tree and to support below the isolation sleeve a production casing hanger for a production casing string. The body also supports a second casing string outside the production casing string whereby to form an annulus between the casing strings. The body includes a passageway which is in communication with the annulus near a lower end of the body and extends upwardly within the wall of the body towards the upper end of the body. A valve is accommodated in the upper part of the body and provides controlled communication between the passageway and a port which can be coupled to the isolation sleeve. The valve is controllable from a production tree in particular is moveable between an open position and a closed position in response to fluid pressure applied to the valve from a production tree by way of the isolation sleeve.