Core barrel for obtaining and retrieving subterranean formation samples

Abstract

Core barrel apparatus for obtaining and retrieving sealed core samples of subterranean formations are disclosed. The core barrel comprises a sample chamber for receiving a core sample as it is formed at the bottom of a bore hole and an expansion chamber for receiving sample fluids. The expansion chamber comprises a cylinder having a movable sealing member therein adapted to movably seal the expansion chamber. The volume of the expansion chamber is determined by the position of the sealing member in the cylinder, movement of the sealing member changing the volume of the expansion chamber. The sample chamber and expansion chamber are selectively connected to one another by means of a seal therebetween. The expansion chamber is sealed closed by the sealing member at one end and said seal at the other end while the sample is being cut and received within the sample chamber. Thereafter, the lower portion of the sample chamber is sealed by a flap-valve and the expansion chamber is opened to the sample chamber. The movable sealing member moves during ascent to expand the expansion chamber and reduce the pressure therein. A cup-like member, a piston, a spheroidal member, and a bellows member are disclosed to be embodiments of the movable sealing member. Valving is provided in the sample and expansion chambers so that the chambers may be individually sealed and separated, and sample fluids removed from the chambers through the respective valves.