Abstract: A subsea test tree assembly is provided which includes at least one subsea test tree or SSTT, the SSTT including a valve having at least one of a cutting function and a sealing function, the valve being movable between an open position and a closed position via hydraulic fluid supplied to the valve through control lines; and a control system including a source of hydraulic fluid, the control system being arranged to supply hydraulic fluid from the source of hydraulic fluid to the valve of the at least one SSTT on detecting that the control lines have been sheared, to automatically move the valve to the closed position. A method of controlling a well using an SSTT assembly is also provided.

Abstract: A subsea test tree assembly is provided which includes at least one subsea test tree or SSTT, the SSTT including a valve having at least one of a cutting function and a sealing function, the valve being movable between an open position and a closed position via hydraulic fluid supplied to the valve through control lines; and a control system including a source of hydraulic fluid, the control system being arranged to supply hydraulic fluid from the source of hydraulic fluid to the valve of the at least one SSTT on detecting that the control lines have been sheared, to automatically move the valve to the closed position. A method of controlling a well using an SSTT assembly is also provided.

Abstract: A fluid control system includes an apparatus comprising a first and second fluid port, first and second control lines, a valve arrangement being configurable between a first state in which the first fluid port is in fluid communication with the first control line and the second fluid port is in fluid communication with the second control line, wherein the apparatus is switchable between first and second configurations responsive to pressure differentials between the first and second control lines, and a second state in which the second fluid port is in fluid communication with a pressurized line and the first fluid port is in fluid communication with a vent arrangement to thereby configure the apparatus into the second configuration, and a control arrangement for reconfiguring the valve arrangement between the first and second states in response to an actuation signal.

Abstract: A fluid control system includes an apparatus comprising a first and second fluid port, first and second control lines, a valve arrangement being configurable between a first state in which the first fluid port is in fluid communication with the first control line and the second fluid port is in fluid communication with the second control line, wherein the apparatus is switchable between first and second configurations responsive to pressure differentials between the first and second control lines, and a second state in which the second fluid port is in fluid communication with a pressurized line and the first fluid port is in fluid communication with a vent arrangement to thereby configure the apparatus into the second configuration, and a control arrangement for reconfiguring the valve arrangement between the first and second states in response to an actuation signal.

Abstract: A landing string includes a valve having a valve member mounted within a flow path extending through the landing string, and a valve control system for use in operating the valve to move the valve member between open and closed positions to control flow along the flow path. The valve control system is reconfigurable between a first configuration in which the valve is operated or controlled under a fail-as-is (FAI) mode of operation, and a second configuration in which the valve is operated or controlled under a fail-close (FC) mode of operation.

Abstract: A landing string includes a valve having a valve member mounted within a flow path extending through the landing string, and a valve control system for use in operating the valve to move the valve member between open and closed positions to control flow along the flow path. The valve control system is reconfigurable between a first configuration in which the valve is operated or controlled under a fail-as-is (FAI) mode of operation, and a second configuration in which the valve is operated or controlled under a fail-close (FC) mode of operation.