High Frequency, Semiconductor Nanomembrane based Pressure and Flow Sensors for Geothermal Applications, Topic 21a

The advanced management of subsurface geothermal facilities requires accurate experimental information about the dynamic pressure and flow status in the subsurface. Such data is the key for the sites to establish models concerning fluid injection, transport, migration, and leakage detection. The combination of subsurface temperature and pressure presents significant technical challenges for the implementation of the pressure and flow sensing devices, as well as the onboard signal processing and data transfer electronics. Semiconductor nanomembrane sensor skins are thin, mechanically, and chemically robust materials that may be patterned in two dimensions to create multi-sensor element arrays that can be conformally attached onto material and model surfaces. The company has demonstrated the feasibility of nanomembrane transducer materials for the measurement of dynamic normal pressure and flow profile in high Reynolds-number environments. For real-time pressure and flow/leakage measurements, the team proposes a time-of-flight based method by using multiple pairs of high frequency nanomembrane sensing elements to pick up pressure waveforms from upstream and downstream locations. This program will develop semiconductor nanomembrane based sensors for subsurface monitoring. The company will improve the current mechanical and electrical model of semiconductor nanomembrane based sensor performance that will allow quantitative optimization of material properties and suggest optimal methods for sensor deployment for pressure and flow measurement applications at geothermal facilities. The team will perform synthesis of sensor materials with optimized transduction, hysteresis and environmental properties, specifically for pressure and flow. The team will perform complete analysis of sensor cross-sensitivities and noise sources to allow the optimization of signal-to-noise ratio and practical sensor sensitivity. Support downhole electronics will be developed to acquire, multiplex, store and process raw sensor array data. The commercialization potential of the nanomembrane technology developed through this program lies in three areas, namely 1) sensors for the measurement of high frequency pressure profile, 2) time-of-flight sensors for the measurement of high frequency flow profile, and 3) the data processing and communication modules.