| CPC E21B 34/08 (2013.01) [E21B 2200/05 (2020.05)] | 19 Claims |
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19. A method for actuating a secondary subsurface safety valve, comprising:
applying a threshold pressure to a control line disposed within a main body to drive a primary flow tube in an axially downhole direction with respect to the main body, wherein a retrievable lock mandrel is secured to the primary flow tube and an opening prong is secured to the retrievable lock mandrel such that the opening prong moves in the axially downhole direction to contact and drive a secondary flapper to an open position in response to movement of the primary flow tube in the axially downhole direction, and wherein the secondary flapper is secured to a secondary valve seat that is secured to the main body in a position downhole from the primary flow tube; and
releasing pressure to the control line, wherein a spring assembly biases the primary flow tube in an axially uphole direction in response to pressure in the control line falling below the threshold pressure, wherein the opening prong is moves in the axially uphole direction to release the secondary flapper to move into a closed position in response to the primary flow tube moving in the axially uphole direction.
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