Control system for an annulus balanced subsurface safety valve

摘要

A control system (10) for an annulus balanced subsurface safety valve (12). A system for operating a safety valve in a well includes a piston (38) of the safety valve being responsive to displace due to a pressure differential between chambers exposed to the piston; and a valve controller (24) which alternately exposes at least one of the chambers to pressure in an annulus surrounding the safety valve, and to pressure greater than that in the annulus. A method of operating a safety valve in a well includes the steps of: opening the safety valve by biasing a piston of the safety valve to displace in response to a pressure differential between a chamber exposed to pressure greater than well pressure, and another chamber exposed to well pressure; and closing the safety valve by exposing both of the chambers to the well pressure.