| CPC E21B 34/106 (2013.01) [E21B 34/101 (2013.01); E21B 2200/05 (2020.05)] | 23 Claims |

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1. A wireline retrievable safety valve for use in a tubing retrievable safety valve (TRSV) disposed downhole in a wellbore, comprising:
a body having a bore therethrough, a control port, and a balance port;
an operating piston;
a balance piston having a head and a rod; and
a valve having an open position and a closed position;
wherein:
the control port is in fluid communication with a first side of the operating piston;
the balance port is in fluid communication with a first side of the balance piston head;
a second side of the operating piston and a second side of the balance piston head are configured to be in fluid communication with the wellbore through one or more wellbore pressure ports;
the balance piston rod extends outward from the first side of the balance piston head;
the balance piston rod is configured to be in fluid communication with the wellbore;
the operating piston and the balance piston are linked to move together; and
the valve is configured so that sufficient pressure applied to the operating piston through the control port opens the valve.
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