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Disclosed is a circulation valve for use in the testing of an oil well wherein the circulation valve may be reclosed by application of well annulus pressure to allow a subsequent treating or testing program. A spring means is subjected to well annulus pressure on two ends of a volume of fluid. The v

Disclosed is a circulation valve for use in the testing of an oil well wherein the circulation valve may be reclosed by application of well annulus pressure to allow a subsequent treating or testing program. A spring means is subjected to well annulus pressure on two ends of a volume of fluid. The volume of fluid is divided by a dividing means which includes pressure relief means such that fluid on one side of the dividing means is either higher or lower than the well annulus pressure. This different pressure is applied to one set of a piston means, and the other side of the piston means is subject to well annulus pressure such that movement of the piston means may be controlled by changing the well annulus pressure. An indexing means is additionally disclosed which controls opening of the circulation valve after a selected number of piston means movements, and which closes the circulation valve upon a selected movement of said piston means when the circulation valve is in the open condition.

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