An extension of gases-brine mutual solubility models to include geochemical reactions: Modeling and applications.

Accurate and quantitative numerical modeling of phase behavior and speciation of gas-water-rock systems is crucial for fluid and rock evolution analysis, and important in scientific research and engineering applications. In our previous work, mutual solubility models of series gases and brine have been developed for wide temperature, pressure and composition ranges. The gas components included CO2, CH4, H2S, N2 and O2. The existing experimental data can be reproduced accurately. In this paper, the models are extended to include water-rock interactions by means of a full coupling with the open-source software package PHREEQC. With the new coupled model, the solubility of gases and various minerals can be correctly and reliably reproduced. The proposed numerical framework is properly implemented and it can be applied in different scenarios of gas-water-rock interactions. Three practical applications have been investigated: calculation of uranium in situ leaching, CO2 geological storage and natural gas souring are provided in the paper. The application cases have additionally proven the stability and reliability of the proposed model.