| 摘要 |
<p>An improved subsea wellhead including a wellhead housing (24) landed at a subsea well location and having a plurality of hangers (28, 36, 44) landed therein, each of the hangers having a seal assembly (32, 40, 48) to define an annulus in the area between the exterior of the hanger and the interior of the wellhead housing below the seal provided by the seal assembly and a passage (52, 54, 56) in said wellhead housing communicating with each of the annuli. The passages extend through the wellhead housing and communicate with the space above the upper surface of the wellhead housing. A spool 72 connected to the upper end of the wellhead housing (24) and inner and outer seals (74, 76) between the upper end of the wellhead housing and the spool define the space into which the passages communicate. A passage (80) extends upward through the spool to communicate the pressure changes in the space between the spool and wellhead housing to the surface. Check valves (66, 68, 70) in each of the passages allow flow upwardly therethrough and prevent flow downwardly therethrough to isolate each of the annuli from the other annuli. In a modified form individual passages with suitable sealing means are provided for each of the wellhead housing passages.</p> |
