Abstract: A hydraulic control system for controlling a plurality of remotely positioned hydraulically actuated underwater devices by a single hydraulic control line extending underwater. A reference hydraulic manifold is connected to the single control line and a signal hydraulic manifold is connected to the single control line. A pilot actuated hydraulic control valve is connected to each of the underwater devices controlling the flow of actuating fluid thereto. The pilot of each valve is connected to both the reference manifold and the signal manifold, but the pilot of each of the valves is actuated by different pressure levels in the signal manifold whereby the underwater devices may be controlled in a predetermined sequence by applying predetermined pressure levels to the single hydraulic control line. A pressure regulator is positioned in the control line upstream of the reference manifold to maintain the reference manifold at a predetermined pressure level.

Abstract: A method of and apparatus for measuring and monitoring the annulus pressure between coaxial well conduits by providing a pressure measuring means which is adapted to be positioned in the well in the annulus and which is movable in response to pressure, and measuring means measuring the movement of the movable pressure measuring means, and transmitting the measurement to the well surface. Pressure measuring means may include a movable element exposed to the pressure in the annulus and a pressure charge chamber acting on the element opposing the movement caused by the pressure in the annulus. The pressure chamber and movable elements may be annular and surround the exterior of the interior conduit. The measuring means includes sensor means adapted to be moved in the well in the interior of the interior conduit to a position adjacent but spaced from the pressure measuring means for providing measurements by signal waves.