Patent ID: 7325597

Claim:
Apparatus for continuously measuring pressure of a wellbore fluid in a wellbore at a downhole location, the apparatus comprising: a conduit positioned in the wellbore and having a flow path extending from the surface to a downhole housing, the downhole housing defining a monitoring-gas chamber, the housing in fluid communication with the flow path in the conduit and with the wellbore, a pressurized monitoring-gas source for pressuring the flow path in the conduit and at least a portion of the monitoring-gas chamber with a selected monitoring gas, a check valve assembly having a check valve housing defining a check valve chamber, an operating member disposed within the check valve chamber, the operating member movable between an open position wherein fluid communication between the wellbore and the surface along the flow path of the conduit is allowed and a sealed position wherein fluid communication between the wellbore and the surface along the flow path of the conduit is prevented, the operating member movable to the sealed position by floating on an activating fluid.