| 摘要 |
A WELLHEAD ASSEMBLY (10) MADE UP OF A WELLHEAD HOUSING (12, 70), A PRODUCTION TREE MOUNTED ON THE WELLHEAD HOUSING (12, 70), TUBING (16) SUSPENDED INTO A WELLBORE FROM WITHIN THE WELLHEAD HOUSING (12, 70), AND AN ANNULUS (22, 80) BETWEEN THE TUBING (16) AND THE WELLHEAD HOUSING (12, 70). A SHUTTLE VALVE IS PROVIDED WITHIN A TUBING HANGER (14, 44) THAT SUPPORTS THE TUBING (16) FROM WITHIN THE WELLHEAD HOUSING (12, 70). AN ACCUMULATOR (82) IS DISPOSED IN THE ANNULUS (22, 80) THAT IS IN FLUID COMMUNICATION WITH A CLOSED POSITION PORT (58, 60) ON THE SHUTTLE VALVE. PRESSURE IS MAINTAINED IN THE ACCUMULATOR (82) FOR CLOSING THE SHUTTLE VALVE WHEN A FORCE FOR OPENING THE VALVE IS REMOVED. THE MOST ILLUSTRATIVE DRAWING IS |
