QUARTZ THICKNESS-SHEAR MODE PRESSURE SENSOR DESIGN FOR ENHANCED SENSITIVITY

Companies in the oil and gas industry rely upon acquisition of accurat e downhole pressure data for management of reservoir resources. Pressu re data must be acquired in extreme environments present in wells, inc luding high pressures, high temperatures, and high levels of shock and vibration. A primary concern of oil and gas companies is that pressur e transducers provide reliable data throughout the duration of well-te sting jobs. Important performance parameters for well-test pressure ga uges include inaccuracy arising from nonlinearity, hysteresis, nonrepe atability, and temperature. Accurate pressure measurements are require d for determination of reservoir resources. Sensor output per unit pre ssure (sensitivity) and the corresponding minimum resolvable pressure (resolution) are important performance considerations. Pressure resolu tion is the key parameter for dynamic well-test analyses used to deter mine reservoir properties. Design limits, including maximum allowable pressure over the operating temperature range, also must be known. Pre ssure transducers must retain acceptable performance characteristics i ncluding accuracy, sensitivity, and resolution for long periods of ope ration to provide reliable data and reduce the frequency and cost of r ecalibration. This paper describes a unique quartz thickness-shear mod e sensor that was developed for downhole pressure measurements. Pressu re transducers that use this sensor meet the demanding requirements of downhole testing.