Abstract: A hydraulic protection system for preventing collapse of a hydraulic line is provided. The system includes a pressure sensing assembly which is arranged to monitor a pressure differential between fluid external to and fluid contained within the hydraulic line; a pressure compensation assembly adapted to be coupled to the hydraulic line. In the event of a loss of pressure in the hydraulic line occurring, the pressure compensation assembly employs the pressure of the fluid external to the hydraulic line to increase the pressure of the fluid contained within the hydraulic line. The system is arranged so that the pressure compensation assembly is operated when the pressure differential monitored by the pressure sensing assembly reaches a predetermined level, which is below a collapse pressure of the hydraulic line, so that exposure of the hydraulic line to the collapse pressure is avoided.

Abstract: A valve assembly for controlling fluid communication along a well tubular that includes hydraulically operated valve that includes a valve member movable between open and closed positions, and a hydraulic actuator for moving the valve member; a control system for selectively controlling the flow of hydraulic fluid to and from the actuator; a vent chamber for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position; and a vent conduit for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position. The control system has a first valve closing state in which the vent chamber is isolated from the actuator. The control system has a second valve closing state in which fluid exhausted from the actuator during movement of the valve member to its closed position is vented into the vent chamber.

Abstract: A valve assembly (100) is disclosed, for controlling fluid communication along a well tubular (10). The valve assembly comprises: a hydraulically operated valve (40, 42) comprising a valve member (41, 43) which is movable between open and closed positions, and a hydraulic actuator (148) associated with the valve member for moving the valve member between these positions; a control system (146) for selectively controlling the flow of hydraulic fluid to and from the actuator, to operate the valve; a vent chamber (84) operatively connectable to the actuator, for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position; and a vent conduit (172) operatively connectable to the actuator, for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position, the vent conduit being exposed to fluid external to the valve assembly at the prevailing external pressure.

Abstract: A hydraulic protection system (46) for preventing collapse of a hydraulic line (38). The system comprises a pressure sensing assembly (50) which is arranged to monitor a pressure differential between fluid external to the hydraulic line and fluid contained within the hydraulic line; and a pressure compensation assembly (52) which is adapted to be coupled to the hydraulic line and which is exposed to the fluid external to the hydraulic line. The pressure compensation assembly (52) is operable to employ the pressure of the fluid external to the hydraulic line to increase the pressure of the fluid contained within the hydraulic line and thereby compensate for the loss. The system is arranged so that the pressure compensation assembly (52) is operated when the pressure differential monitored by the pressure sensing assembly (50) reaches a predetermined level, which is below a collapse pressure of the hydraulic line.