Abstract: A method can include determining that measured outputs of first and second sensors are correlated, calculating a second sensor output based on the measured first sensor output, and in response to a loss of the measured second sensor output or a failure of an item of equipment, controlling a drilling operation based on the calculated second sensor output. A control system can include a statistical model that determines a correlation between measured outputs of first and second sensors, and calculates a calculated second sensor output based on the measured first sensor output, a controller that controls the drilling operation, and a hydraulics model that determines how the drilling operation should be controlled to achieve a desired objective, and determines, based on the calculated second sensor output, how the drilling operation should be controlled, in response to a loss of the measured second sensor output or an equipment failure.

Abstract: A differential pressure indicator (DPI) for use with a downhole isolation valve includes a tubular mandrel for assembly as part of a casing string and for receiving a tubular string. The mandrel has a stop shoulder and a piston shoulder. The DPI further includes a tubular housing for assembly as part of the casing string and for receiving the tubular string. The housing is movable relative to the mandrel between an extended position and a retracted position and has a stop shoulder and a piston shoulder. The DPI further includes a hydraulic chamber formed between the piston shoulders and a coupling in communication with the hydraulic chamber and for connection to a sensing line. The housing is movable relative to the mandrel and to the extended position in response to tension exerted on the DPI.

Abstract: A differential pressure indicator (DPI) for use with a downhole isolation valve includes a tubular mandrel for assembly as part of a casing string and for receiving a tubular string. The mandrel has a stop shoulder and a piston shoulder. The DPI further includes a tubular housing for assembly as part of the casing string and for receiving the tubular string. The housing is movable relative to the mandrel between an extended position and a retracted position and has a stop shoulder and a piston shoulder. The DPI further includes a hydraulic chamber formed between the piston shoulders and a coupling in communication with the hydraulic chamber and for connection to a sensing line. The housing is movable relative to the mandrel and to the extended position in response to tension exerted on the DPI.