دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a coring technique in which core samples are obtained from the hole wall in a zone that has already been drilled. A hollow bullet is fired into the formation wall to capture the core and then retrieved on a flexible steel cable. Core samples of this type usually range from 1 to 13/16 inches (20 to 30 millimetres) in diameter and from 1 to 4 inches (20 to 100 millimetres) in length. This method is especially useful in soft-rock areas.