Horizontal tree safety valve system Horizontal tree safety valve and process to isolate a wellhead and allow new entry into the well

摘要

PCT No. PCT/GB94/02787 Sec. 371 Date Jun. 19, 1996 Sec. 102(e) Date Jun. 19, 1996 PCT Filed Dec. 21, 1994 PCT Pub. No. WO95/17578 PCT Pub. Date Jun. 29, 1995A safety valve for use with horizontal subsea trees as described which uses a two-part (10, 12) safety valve system. The first part (10) containing a valve mechanism (16, 18, 22, 26) remains in the wellhead and is normally biased to a closed position. The valve mechanism (16, 18, 22, 26) remains in the wellhead at all times during production and can be actuated to an open position by latching in a second part (12) which contains control cables (58) and a moveable valve actuator (62, 70, 40, 26) operable from the surface during workover to actuate the valve (18) in the wellhead portion (10) open. This provides for greater safety during the workover phase in comparison to a wire set plug and allows safer re-entry to the well.