Reactive transport modelling of mineral carbonation in Deccan basalts under low-temperature CO ₂ injection conditions: a case study from Killari-1 borehole

The Deccan Traps are emerging as promising targets for long-term CO 2 sequestration via mineral carbonation, owing to their abundant reactive silicate minerals and suitable subsurface conditions. In this study, we develop a one-dimensional reactive-transport model to simulate CO 2 –brine–basalt interactions for a representative mineralogy from the Killari-1 (KLR-1) borehole (Deccan mainland) over a period of five years. The model is anchored to site-specific injection scenario targeted at a 220–265 m depth interval of enhanced porosity (∼6%) and temperature (T ∼ 57 °C). The model incorporates realistic representative mineralogical assemblages of clinopyroxene and plagioclase feldspar and without any olivine. Dissolution kinetics based on rate laws drive cation release, while CO 2 dissolution acidifies pore water; as pH rebounds (via silicate buffering) the model kinetically precipitates carbonate minerals (calcite, siderite, ankerite) and clay phases (smectite, chlorite). The simulations predict substantial carbonate and little clay mineral precipitation, which in turn buffers the fluid chemistry and are consistent with field observations from known basaltic storage projects. Our study is novel in incorporating initial petrophysical and geochemical analyses based on data from the Killari-1 borehole and applying them to a shallow-depth (moderate-temperature) Deccan basalt setting, in contrast to prior work focused on deep, high-temperature systems. Despite the current model's limitations of considering 1-D advective isothermal, single phase flow assumptions, homogeneous mineralogy, reliance on literature derived kinetic data and absence of geo-mechanical coupling, present study offers a first–order assessment of the carbonation potential of Deccan mainland basalt and establishes a reactive-transport framework for future site-specific CO 2 storage design.