Subsea well pressure monitor

DETAILED DESCRIPTION In this invention, the pressure is monitored by a stationary unit that mounts to the exterior of the tubular member, such as an inner wellhead housing, in which pressure is to be monitored.
The sensor is preferably a strain gage that will monitor tensile strain in the tubular member that would occur if there was an increase in pressure.
The strain gage connects to an oscillator for varying the frequency of the oscillator depending upon the strain sensed by the strain gage.
This variance is compared with a reference oscillator also mounted to the exterior of the wellhead housing.
The difference between the reference frequency and the variable frequency corresponds to the pressure increase.
This difference is applied to a light emitter, such as a light emitting diode for creating pulses.
Power for the stationary unit is supplied by a photocell mounted in the stationary unit.
When pressure is to be monitored, a remote operated vehicle (ROV) will be lowered next to the wellhead housing.
The ROV has a laser which will supply a beam of light to the photocell to power the components of the stationary unit.
The light pulses emitted by the light emitter will be received by receiver mounted in the ROV.
The receiver has a decoder, which preferably is a frequency counter for counting the pulses.
This data can be recorded or transmitted to the surface over a data line of the ROV.