This STTR will pioneer a challenging and highly rewarding development. âSensor Ballsâ will be realized approximately 1 mm in diameter. A sensor ball contains four components on a single silicon chip: (i) inertial sensors, (ii) memory, (iii) a sensor to log a measurand of interest (e.g. temperature or pressure), and (iv) a module for data transfer. The ball is small enough to traverse through many subsurface scenarios of interest. This vision is as follows: The ball takes a journey through a subsurface region of interest, logging the measurand and its trajectory along the way. Ultimately the ball is collected at the surface, where it is captured and interrogated to upload information regarding its journey (i.e. what was measured, where, and when). To fix ideas, envisioning a specific scenario is helpful â the 3D mapping of an entire fracture network in an enhanced geothermal system (EGS). 100s or 1,000s of sensor balls immersed in the fluid take a journey into the deep subsurface, flow from injection to production wells through the fracture network, record measurands of interest, and circulate back to the top. A system is in place at the surface to capture the balls as the fluid passes. This project is an incredibly challenging engineering and systems integration project. Phase I addresses two of the highest risk design blocks head-on. Phase I will also be used to develop a prototype of this system using discrete level components. Phase II will pioneer the realization of this concept on silicon to yield the highly integrated, extremely small sensor ball unlike anything developed to date. The product innovation will address use cases spanning drilling, fracking, and production. Further, the product innovation impacts EGS, closed-loop geothermal fracking for unconventionals, and geological CO2 sequestration sys
