Abstract: In accordance with an illustrative embodiment of the present invention, a full-bore drill stem testing system includes a lower housing member having a ball valve for opening and closing a flow passage extending axially therethrough and an upper housing member having an open axial bore in communication with said flow passage. Downwardly facing recesses are formed in the wall of the upper housing member laterally offset from the open bore, and each recess receives an electrical contact that is connected with transducer means for sensing variables such as pressure and temperature of well fluids below the ball valve. Guide slots having orienting surfaces at their lower ends lead upwardly to each recess. A running tool that is lowered into the upper housing member on electrical wireline has normally retracted arms which carry electrical contacts on their upper ends.

Abstract: In accordance with an illustrative embodiment of the present invention, a surface controlled subsurface safety valve system includes a tubing retrievable safety valve having a valve element that is opened and held open in response to the pressure of a control fluid in a control line and automatically closed when control pressure is reduced, and means for equalizing the pressure of fluids above and below said valve element to aid in reopening the same after closure, including a wireline retrievable equalizing valve removably installed in the pocket of a side pocket mandrel that is connected in the tubing above said safety valve, said equalizing valve being arranged to be opened and closed in response to changes in the pressure of said control fluid. A uniquely constructed side pocket mandrel also is disclosed.

Abstract: In accordance with an illustrative embodiment of the present invention, a subsurface safety valve assembly includes a dome precharged with a set reference pressure that tends to close the valve, and means responsive to both ambient pressure and to the pressure of a control fluid for holding the valve open under normal conditions, a decrease in either control fluid pressure or tubing pressure, or both, enabling the dome pressure to cause the valve to automatically close and shut-in the well. The valve does not employ a coil spring to cause closure, which permits installation at great depths in a well, and a narrow spread between valve opening and closing pressures.

Abstract: In accordance with an illustrative embodiment of the present invention, a subsurface safety valve assembly that automatically closes in response to a drop in flowing pressure at the valve to a value that is below a set dome pressure, is provided with a flow restriction upstream of the valve that is sized to enable rapid closing of the safety valve in the event of disruption of surface flow lines or the like.