Method and apparatus for installing a wireline for logging or other operations in an under-balanced well

摘要

An improved apparatus and a method to insert a wireline through a blow out preventer to log an underbalanced open hole well without killing the well or causing formation damage while maintaining well control during the process. A dual throated blow out preventer (10) provides a moveable sealing element (1210, 1402) to allow a wireline (13) and a drill string (25) to be placed in a well for assembly, then seals off the dual throat to isolate the drill string from the wireline, thereby permitting pressure to be maintained on both the wireline through a standard packoff arrangement (1218) and on the drill string using the rams of the blow out preventer (10).