| Abstract |
This study presents a 1D radial and a 2D cross-sectional reactive transport model developed to simulate fluid-rock interactions resulting from the proposed injection of CO₂-enriched fluids into a geothermal reservoir. The 1D MINC radial model focuses on the major feed zone of a binary-utilized reinjection well K1 at the Mt Apo Geothermal Field, Philippines while the 2D single porosity model intersects the injection well and three production wells with the highest tracer return from said reinjection. The simulation captures key processes such as dissolution, mineral alteration, and secondary mineral precipitation within the feed-zone-to-reservoir flow path. The models were calibrated against actual downhole pressure, chemistry, and tracer returns; and results from the 1D model shows more significant mineral volume changes in the fracture than the matrix in terms of calcite, dolomite, chlorite, smectite, and epidote mainly due to changes in injection chemistry and temperature. Also, comparison of a continued binary utilization and the proposed CO₂-enriched injection shows no significant difference in mineral volume fractions due to relatively similar pH. This modelling approach offers an informative guide for field-scale predictions and supports the development of effective CO₂-geothermal wastewater mixture injection strategies for geothermal reservoir management. |