| 摘要 |
A subsea wellhead assembly comprises a production casing hanger (2) defining a series of passageways (20-24) from an annulus (B) between a production casing string and an outer casing (8) to a region (16) which can communicate, for example by way of an isolation sleeve (9a), with a production tree. The passageways extend to the interior of the casing hanger. A positionally adjustable sleeve (17) fits within the casing hanger and carries exterior seals (25-27) which are disposed so that for a first position of the adjustable sleeve (17) within the casing hanger (2) fluid passage through the series of passageways is blocked and for a second position of the sleeve within the casing hanger said fluid passage is allowed. The adjustable sleeve can be operated by a simple tool through the production tree. |
