Electro-mechanical drilling jar

摘要

A drilling jar comprising a mandrel with a shoulder extending radially outward. The shoulder defines at least one openable and closeable orifice therethrough. An outer housing is slidably disposed about the mandrel to define an upper chamber above the shoulder and a lower chamber below the shoulder. The jar also comprises a magnetorestriction material that responds to a predetermined pressure in the upper chamber to open at least one orifice in the shoulder to allow rapid pressure communication between the upper and lower chambers.