MODELING THE FATE AND IMPACT OF CO2 INJECTED INTO THE MORROW-B SANDSTONE THROUGH NON-ISOTHERMAL REACTIVE TRANSPORT MODELING: A CASE STUDY OF THE FARNSWORTH UNIT, TEXAS
The model results showed a change in the formation water composition that leads to changes in the formation mineralogy. The model predicts a sharp initial drop in pH reflecting the impact of the large mass of CO2 that dissolves in the immediate vicinity of the injectors. Once CO2 injection has ceased, the pH gradually gradually increases, approaching its initial value. In addition to dissolving into the formation water, much of the injected CO2 dissolves into petroleum, with the remainder persisting as an immiscible gas phase. The pH remains low enough throughout the simulation for calcite, a native reservoir mineral, to dissolve continuously. With increasing time, other non-native carbonate minerals, dolomite, ankerite, and siderite, begin to precipitate, becoming significant mineral sinks for CO2 by the end of 1000 year simulation. The changes in mineral abundance, however, do not lead to significant changes in porosity. The results of this study are encouraging for the feasibility of large-scale CO2 sequestration in sandstone hydrocarbon reservoirs.