Quartz thickness-shear mode pressure sensor design for enhanced sensitivity

Companies in the oil and gas industry rely upon the acquisition of accurate downhole pressure data for management of reservoir resources. Pressure data must be acquired in extreme environments present in oil and gas wells including high pressures, high temperatures, and high levels of shock and vibration. A primary concern of oil and gas companies is that pressure transducers provide reliable data when subjected to time varying combinations of pressure and temperature throughout the duration of well-testing jobs. Pressure resolution is the key performance parameter for dynamic well-test analyses used to determine reservoir properties. Design limits including maximum allowable pressures which may be applied over the operating temperature range without degrading transducer performance and maximum pressures which may be applied without leakage or catastrophic failure must also be known. Pressure transducers must retain acceptable performance characteristics including accuracy, sensitivity, and resolution for long periods of operation to provide reliable well-test data and reduce the frequency and cost of recalibration. This paper describes a unique quartz thickness-shear mode sensor which has been developed for downhole pressure measurements. Pressure transducers which use this sensor meet the demanding requirements of downhole testing.