Subsurface safety valve actuator

A subsurface safety valve actuation system comprising:

• tubing arranged in a well and forming a flow channel to a surface level for fluids originating from below said surface level;
• a safety valve in said tubing below said surface level and operable between an open position and a closed position to control a flow of fluids in said flow channel;
• a hydraulic piston assembly in said tubing below said surface level comprising a first chamber and a piston between said first chamber and said safety valve;
• an electric motor in said tubing below said surface level and configured to be supplied with a current;
• a hydraulic pump in said tubing below said surface level and configured to be driven by said motor and connected to said first chamber of said hydraulic piston assembly;
• a spring element in said tubing below said surface level and configured to provide a spring force upon said piston;
• a fluid reservoir connected to said pump and said first chamber;
• a first valve connected to said first chamber and said fluid reservoir and having a first open position and a first closed position;
• a second valve connected to said first chamber and said fluid reservoir and having a second open position and a second closed position;
• said pump, hydraulic piston assembly, first valve, second valve and reservoir connected in a substantially closed hydraulic system;
• wherein said hydraulic system is configured in a first state to provide pressure in said first chamber that drives said safety valve from said closed position to said open position;
• wherein said hydraulic system is configured in a second state to retain a pressure level in said first chamber that retains said safety valve in said open position;
• wherein said hydraulic system is configured in a third state to release said pressure level in said first chamber via a first hydraulic release path between said first chamber and said reservoir that extends through said first valve when said first valve is in said first open position;
• wherein said hydraulic system is configured in a fourth state to release said pressure level in said first chamber via a second hydraulic release path between said first chamber and said reservoir that extends through said second valve when said second valve is in said second open position;
• and
• wherein said first hydraulic release path is at least in part independent from said second hydraulic release path and said second hydraulic release path is at least in part independent from said first hydraulic release path;
• whereby said pressure level in said first chamber that retains said safety valve in said open position may be released via said first hydraulic release path when there is a fault in said second hydraulic release path and may be released via said second hydraulic release path when there is a fault in said first hydraulic release path.