Oilfield apparatus and methods of use

Abstract

The invention provides a flow control valve for a subsea hydrocarbon production system and a method of use. The flow control valve comprises an inlet configured to be in fluid communication to an injection fluid conduit and an outlet configured to be in fluid communication with a subsea flow system. A flow control mechanism is disposed in a flow path between the inlet and the outlet and is arranged to adjust a flow rate through the flow path. The flow control mechanism is configured to automatically adjust the flow rate of injection fluid through the flow path according to a pressure differential between fluid pressure at the inlet and fluid pressure at the outlet. Adjustment may be self-regulating, or may be controlled by a hydraulic control circuit.

1 . A flow control valve for a subsea hydrocarbon production system, the flow control valve comprising:
 an inlet configured to be in fluid communication to an injection fluid conduit;   an outlet configured to be in fluid communication with a subsea flow system;   a flow control mechanism disposed in a flow path between the inlet and the outlet and arranged to adjust a flow rate through the flow path;   wherein the flow control mechanism is configured to automatically adjust the flow rate of injection fluid through the flow path according to a pressure differential between fluid pressure at the inlet and fluid pressure at the outlet.   
     
     
         2 . The flow control valve according to  claim 1 , wherein the flow control mechanism is configured to close to prevent fluid flow in the flow path in a direction from the outlet to the inlet in response to a pressure differential between fluid pressure in the injection fluid conduit and fluid pressure in the subsea flow system. 
     
     
         3 . The flow control valve according to  claim 1 , wherein the flow control mechanism is configured to close in response to a low pressure condition at the injection fluid conduit. 
     
     
         4 . The flow control valve according to  claim 1 , wherein the valve is a pressure balanced valve. 
     
     
         5 . The flow control valve according to  claim 1 , wherein the flow control mechanism is operable by a hydraulic control circuit. 
     
     
         6 . The flow control valve according to  claim 1 , wherein the flow control mechanism is configured to be actuated to close to prevent fluid flow through the flow path by a control signal or by a failsafe close actuation mechanism. 
     
     
         7 . The flow control valve according to  claim 1 , wherein the valve comprises a spool assembly movable in a valve bore. 
     
     
         8 . The flow control valve according to  claim 7 , wherein the spool assembly comprises a choke sleeve assembly. 
     
     
         9 . The flow control valve according to  claim 7 , wherein a position of the spool assembly is operable to be controlled by a torque bucket stem. 
     
     
         10 . The flow control valve according to  claim 9 , wherein a position of the spool assembly is operable to be controlled by a torque bucket stem to define the size of a valve orifice. 
     
     
         11 . The flow control valve according to  claim 7 , wherein the spool assembly comprises a sleeve with a plurality of radial ports. 
     
     
         12 . The flow control valve according to  claim 11 , wherein the sleeve comprises a choke sleeve. 
     
     
         13 . The flow control valve according to  claim 1 , further comprising a check poppet. 
     
     
         14 . The flow control valve according to  claim 1 , wherein the sleeve comprises a choke sleeve, and further comprises a spool piece located internally to the choke sleeve. 
     
     
         15 . The flow control valve according to  claim 14 , wherein the position of the spool piece with respect to the choke sleeve is controlled by a pressure drop across a valve orifice. 
     
     
         16 . The flow control valve according to  claim 14 , wherein the spool piece is movable in the valve to regulate a flow rate through the valve by opening and closing radial ports. 
     
     
         17 . The flow control valve according to  claim 1 , wherein the valve comprises an ambient pressure vent, which functions to close the valve if the pressure at the inlet drops to a pressure below ambient pressure. 
     
     
         18 . A subsea fluid injection system for a subsea hydrocarbon production system, the subsea fluid injection system comprising:
 an injection fluid conduit;   a subsea flow system;   and a flow control valve disposed between the injection fluid conduit and the subsea flow system;   wherein the flow control valve comprises a flow control mechanism disposed in a flow path between the injection fluid conduit and the subsea flow system and arranged to adjust a flow rate of injection fluid passing through the flow path;   and wherein the flow control mechanism is configured to automatically adjust the flow rate of injection fluid through the flow path according to a pressure differential between fluid pressure in the injection fluid conduit and fluid pressure in the subsea flow system.   
     
     
         19 . A hose termination unit for a subsea fluid injection system, the hose termination unit comprising:
 a first coupling for a subsea hydrocarbon production system;   a second coupling for a fluid injection hose;   and a flow control valve disposed between the first and second couplings;   wherein the flow control valve comprises a flow control mechanism comprising a movable spool assembly operable to move in response to a pressure differential in the hose termination unit.   
     
     
         20 . A method of performing a subsea fluid injection operation in a subsea hydrocarbon production system, the method comprising:
 providing an injection fluid conduit coupled to a subsea flow system;   providing a flow control valve between the injection fluid conduit and the subsea flow system;   injecting an injection fluid from the injection fluid conduit to the subsea flow system through a flow path of the flow control valve;   adjusting the flow rate of injection fluid through the flow path automatically using a flow control mechanism responsive to a pressure differential between fluid pressure in the injection fluid conduit and fluid pressure in the subsea flow system.