CPC E21B 34/10 (2013.01) [E21B 34/14 (2013.01); E21B 2200/04 (2020.05)] | 20 Claims |
18. A method, comprising:
providing an isolation valve with an actuation piston slidably disposed along an internal through passage of a surrounding housing;
creating an intermediate chamber between the actuation piston and the surrounding housing such that pressure in the intermediate chamber acts on the actuation piston in a first direction;
exposing the actuation piston to tubing pressure in a second direction opposite the first direction;
preventing the actuation piston from actuating the isolation valve by blocking communication between the intermediate chamber and an atmospheric pressure chamber formed within a wall of the surrounding housing; and
causing shifting of the actuation piston by opening communication between the intermediate chamber and the atmospheric pressure chamber, and transferring fluid from the intermediate chamber into the atmospheric pressure chamber.
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