Continuous pressure and temperature readout for submersible pumps

摘要

A pressure and temperature measuring system for a submersible pump installation provides a continuous reading of both pressure and temperature at the surface and compensates for temperature changes in the pressure readout. The system includes a pair of downhole sensors, each of which provides an electrical resistance change corresponding to pressure or temperature. A switch at the surface alternately applies to the power cable a positive interim of positive DC current and a negative interim of negative DC current. Steering diodes located downhole direct the positive DC current through one of the sensors and the negative DC current through the other of the sensors. The voltage received at the surface corresponds to the resistance of the sensor through which current is passing. Sample and hold circuits sustain the pressure output during the interim of temperature measurement and vice-versa. During pressure measurement, a value corresponding to the temperature potential at the surface is applied as an offset which offsets the pressure potential. The output is a compensated pressure reading which is converted into a pressure indication.