05337827 is referenced by 91 patents and cites 10 patents.

In the present invention a testing tool having an axial flow passage is arranged to be connected in a pipe string and placed in a well bore. Communication through the flow passage is controlled by a valve member which is cooperatively arranged in the body to be moved back and forth for selectively opening and closing communication through the flow passage. The testing tool further includes upper and lower mandrels that are selectively coupled together by a unique clutch mechanism that enables the valve member to be successively opened and closed as the well bore pressure is increased and decreased a predetermined number of times in a testing cycle. The clutch mechanism is thereafter operable for temporarily uncoupling the mandrels to enable the valve member to be retained in its open position as the well bore pressure is increased and decreased in a subsequent operating cycle of the test valve before resuming the testing operation.

Title
Pressure-controlled well tester adapted to be selectively retained in a predetermined operating position
Application Number
263573
Publication Number
5337827
Application Date
October 9, 1991
Publication Date
August 16, 1994
Inventor
Dinesh R Patel
Sugar Land
TX, US
Joe C Hromas
Sugar Land
TX, US
Agent
John H Bouchard
Henry N Garrana
Assignee
Schlumberger Technology Corporation
TX, US
IPC
E21B 34/10
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