Patent ID: 8602108
Filing Date: 2013-12-10
Classification: E21B

Abstract:
1. A subsurface test tree system, the system comprising: a subsea test tree having a safety valve, the subsea test tree connectable with a blowout preventer stack below a water surface; a subsea control system operationally connected with the subsea test tree below the water surface to actuate the safety valve, wherein the subsea control system does not include a microprocessor; a surface control station positioned at a surface location, the control station including a microprocessor; and an umbilical operationally connecting the control station and the subsea control system to actuate the safety valve in response to a signal sent from the control station to the subsea control system, wherein the control station provides an electric current through a conductor in the umbilical to actuate the safety valve via the subsea control system, and the subsea control system comprises a diode steering circuit to demultiplex the electric current received.