Apparatus for formation testing

摘要

A formation testing system provides the ability to reliably and repeatedly perform tests, such as drawdown tests, on closely spaced apart formations intersected by subterranean wellbores without relying on absolute fluid pressure for actuation thereof. The formation testing system is configured for normal drilling operations or for fluid sampling operations by applying preselected differential pressures to the system. The formation testing system includes opposing pistons (68,74) which cooperate to open and close a valve. <IMAGE>