A Numerical Study of Selective Inorganic Precipitation in Fractures to Geoengineer Resilient and Secure Underground Storage Sites
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AbstractA process to geoengineer hydrodynamic seals is investigates numerically. It is well-documented that upon mixing, Barium- and sulfate-rich brines lead to rapid deposition of impermeable and stable scale. When deposited within open fractures, the mineral scale also holds significant tensile strength. This work investigates the intentional injection of these incompatible ions into faulted formations and around caverns to create mechanically resilient hydrodynamic seals. A coupled hydrological-mechanical-chemical HMC model is calibrated to available bench-scale experimental observations. The model attains a close match with experimental core-flooding observations by fitting reaction rate, solubility, precipitation, and nonequilibrium formation blockage. It is then applied to conduct field-scale investigations of various synthetic operational injection scenarios. The calibrated simulations suggest that the saturation index of the injected brines, injection patterns, and rates have a first-order impact on seal creation and uniformity. With inorganic precipitation, the critical injection rates to triggering seismic nucleation may be reinforced by one to two orders in magnitude due to cohesive mechanical healing.
