Subsea pressure control system

Abstract

A subsea pressure control system includes an inlet flowline, a pressure sensing device coupled into the inlet flowline and in fluid communication with the inlet flowline, a controller coupled to the pressure sensing device, an actuator coupled to the controller, and a valve coupled to the actuator and a fluid outlet. The controller may be responsive to the pressure sensing device, the actuator may be responsive to the controller, and the valve may be responsive to the actuator to regulate a measured pressure of the pressure sensing device at or below a setpoint pressure. Another subsea pressure control system includes a controller responsive to a setpoint pressure in a flowline, and a valve responsive to a signal from the controller, wherein the signal is based on the setpoint pressure and actuates the valve from a closed position to an open position.

1 . A subsea pressure control system comprising:
 an inlet and an inlet flowline;   a pressure sensing device coupled into the inlet flowline and in fluid communication with the inlet flowline;   a controller coupled to the pressure sensing device;   an actuator coupled to the controller; and   a valve coupled to the actuator and a fluid outlet.   
     
     
         2 . The system of  claim 1  wherein the controller is responsive to the pressure sensing device. 
     
     
         3 . The system of  claim 2  wherein the controller comprises a setpoint pressure and is configured to compare the setpoint pressure to a measured pressure of the pressure sensing device. 
     
     
         4 . The system of  claim 1  wherein the actuator is responsive to the controller. 
     
     
         5 . The system of  claim 4  wherein the valve is responsive to the actuator. 
     
     
         6 . The system of  claim 5  wherein the actuator is responsive to the controller based on a setpoint pressure to move the valve between a closed position isolating the inlet flowline from the fluid outlet and an open position exposing the inlet flowline to the fluid outlet. 
     
     
         7 . The system of  claim 6  wherein the valve is moved to the open position if a measured pressure of the pressure sensing device exceeds the setpoint pressure, and the valve is moved to the closed position if the measured pressure is at or below the setpoint pressure. 
     
     
         8 . The system of  claim 1  wherein the actuator is operably coupled to the valve to selectively expose the inlet flowline to the fluid outlet. 
     
     
         9 . The system of  claim 1  wherein the pressure sensing device measures a fluid pressure in the inlet flowline. 
     
     
         10 . The system of  claim 1  wherein the pressure sensing device comprises a pressure transducer. 
     
     
         11 . The system of  claim 1  wherein the controller comprises an electronic control module and the actuator comprises an electric actuator. 
     
     
         12 . The system of  claim 1  wherein the pressure sensing device and the controller comprise a master hydraulic cylinder and a slave hydraulic cylinder. 
     
     
         13 . The system of  claim 1  wherein the actuator comprises a hydraulic actuator. 
     
     
         14 . The system of  claim 1  wherein the valve comprises a choke. 
     
     
         15 . The system of  claim 1  further comprising a flowline coupled between the inlet and a subsea wellhead manifold. 
     
     
         16 . The system of  claim 1  further comprising at least one backup pressure control subsystem coupled to the inlet. 
     
     
         17 . A subsea pressure control system comprising:
 a flowline configured for connection into a subsea fluid containment system;   a controller configured to be responsive to a setpoint pressure in the flowline; and   a valve configured to be responsive to a signal from the controller, wherein the signal is based on the setpoint pressure and actuates the valve from a closed position to an open position to expose the flowline to the sea or a container.   
     
     
         18 . The system of  claim 17  further comprising a pressure sensing device configured to be responsive to a measured pressure in the flowline, wherein the signal is based on the measured pressure exceeding the setpoint pressure. 
     
     
         19 . The system of  claim 18  wherein the valve is responsive to a second signal from the controller, wherein the second signal is based on the measured pressure equaling or falling below the setpoint pressure, and the second signal actuates the valve from the open position to the closed position to isolate the flowline from the sea or the container. 
     
     
         20 . The system of  claim 17  further comprising at least one backup pressure control subsystem coupled to the flowline, wherein the backup pressure control subsystem is operable if the valve fails to actuate from the closed position to the open position. 
     
     
         21 . A method of controlling a pressure in a subsea fluid containment system, comprising:
 determining a setpoint pressure for a subsea pressure control system;   coupling the subsea pressure control system into the subsea fluid containment system;   measuring a pressure of the subsea fluid containment system;   comparing the measured pressure to the setpoint pressure; and   exposing the subsea fluid containment system to the sea or a container using the subsea pressure control system if the measured pressure exceeds the setpoint pressure.   
     
     
         22 . The method of  claim 21  further comprising isolating the subsea fluid containment system from the sea using the subsea pressure control system if the measured pressure falls below the setpoint pressure. 
     
     
         23 . The method of  claim 21  further comprising adjusting the setpoint pressure while subsea. 
     
     
         24 . The method of  claim 21  further comprising modulating the measured pressure. 
     
     
         25 . The method of  claim 21  further comprising opening a backup subsystem to expose the subsea fluid containment system to the sea.