Acquiring specific data about the reservoir pressure and temperature, near the wellbore and far out in the formation, and correlating such information to fracture connectivity and geometry are key for the optimum energy extraction from geothermal resources. Existing fracture characterization tools and analysis approaches are inadequate, in that pressure and temperature are measured only at the wellbore. Technological advancement in nanoscience could provide a boost in the area of reservoir in-situ measurements through the concept of nanosensing.

This paper provides some details of initial experimental work done so far towards the ultimate goal of making temperature and pressure nanosensors from which a new method will be developed to predict reservoir parameters and characterize fracture networks in geothermal reservoirs. The paper addresses the feasibility of using nanomaterials as tracers in sensing the reservoir properties in-situ. Preliminary testing with the injection of various nanofluid suspensions (nanoparticles and nanowires) was carried out to investigate the viability of transporting nanomaterials through a porous medium. This is a critical step toward the development of functional nanosensors. Berea sandstone and sand-packed slim tube were used in the nanofluid injection experiments. The nanoparticles injected into Berea sandstone samples have provided a proof of concept in the use of nanoparticles as tracers. The nanoparticles were transported through the pore space of the rock and were detected in the effluent. The nanoparticles were also recovered through the 10 meter long sand-packed slim tube. Following the successful injection of spherically shaped nanoparticles, an investigation was initiated to assess the practicability of transporting wire-like nanoparticles (silver nanowires) through the pores of Berea sandstone. These nanowires serve as precursor for the injection of functional nanosensors such as pressure- and temperature-sensitive nanotracers. It was found that the silver nanowires of that particular size could not pass through the pore spaces of the core sample.

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