Abstract: In accordance with an illustrative embodiment of the present invention as disclosed herein, a combination slip joint-safety valve tool includes telescoping mandrel and housing members, a full-opening valve on the housing member operable when closed to prevent upward flow of fluid through said members, and hydraulically operable valve actuator means responsive to contraction of said telescoping members for closing said valve and to extension of said members for opening said valve.

Abstract: In accordance with an illustrative embodiment of the present invention, a pressure controlled reversing valve includes a housing having a flow passage and ports to communicate the passage with the well annulus outside the housing, valve means for normally closing said ports, valve operator means movable upwardly and downwardly in said housing in response to changes in the pressure of fluids in said annulus, lost-motion coupling means for enabling movement of said operator means independently of said valve means so long as said pressure does not exceed a first predetermined value, and means for converting said lost-motion coupling to a driving connection in response to a second pressure in excess of said first pressure to cause said operator to shift said valve means from closed to open position.

Abstract: Methods and apparatus for performing a drill stem test of an offshore well utilizing a pressure controlled test valve. The test valve includes a valve element having a transverse pressure area with the high pressure side exposed to the pressure of fluids in the well annulus and the low pressure side subject to the pressure of a compressible fluid medium contained within a chamber in the test valve. The pressure in the chamber is equalized with the hydrostatic head of the well fluids so that at test depth the same pressure is acting on both sides of the transverse pressure area, whereupon this pressure is confined within the chamber. Then a fluid pressure in excess of the hydrostatic head is applied to the well fluids externally of the test valve to develop a pressure difference across the valve element which causes it to shift from closed to open position.