Flow through permeable zones in the subsurface is the key to modern energy production. In geothermal systems, this involves injecting fluid along ideal flow pathways such as fractures and faults in order to extract heat. However, the efficiency of the heat extraction may be greatly diminished if the injected fluid travels in part through non-ideal flow zones which are excessively permeable or not well connected to the withdrawal well. In order to treat these non-ideal flow paths in geothermal reservoirs, a porous polymer has been developed that can restrict flow by partially sealing these non-ideal flow zones. This polymer will be distributed through a temperature-activated microcapsule. The focus of this work is how these microcapsules will flow and become trapped in a network system in the subsurface. We develop a high-temperature high-pressure flow loop for injecting microcapsules into a porous network. Using polyethylene microcapsules to simulate the final microcapsules developed in this study, we injected the microcapsules into a porous reservoir material while varying parameters during testing such as injection fluid viscosity, gravel size, and microcapsule properties. The results indicated that the final microcapsules will be able to enter the network, but that most of the particulates will block the matrix near to the porous media rather than penetrate throughout. We used CT scanning to show that in most cases the microcapsules either completely passed through the gravel sample or sealed the near-entrance pore spaces. Further work with fracture geometries will allow us to show how microcapsule behavior depends upon the structure of the network. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. This presentation describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. SAND2024-13594A

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