A Geochemical Model of Fluids and Mineral Interactions for Deep Hydrocarbon Reservoirs

Abstract

A mutual solubility model for CO 2 -CH 4 -brine systems is constructed in this work as a fundamental research for applications of deep hydrocarbon exploration and production. The model is validated to be accurate for wide ranges of temperature (0-250 ∘ C), pressure (1-1500 bar), and salinity (NaCl molality from 0 to more than 6 mole/KgW). Combining this model with PHREEQC functionalities, CO 2 -CH 4 -brine-carbonate-sulfate equilibrium is calculated. From the calculations, we conclude that, for CO 2 -CH 4 -brine-carbonate systems, at deeper positions, magnesium is more likely to be dissolved in aqueous phase and calcite can be more stable than dolomite and, for CO 2 -CH 4 -brine-sulfate systems, with a presence of CH 4 , sulfate ions are likely to be reduced to S 2− and H 2 S in gas phase could be released after S 2− saturated in the solution. The hydrocarbon "souring" process could be reproduced from geochemical calculations in this work.

A Study on the Dissolution Behavior of Typical Minerals in Continental Deposited Reservoirs during CO2 Geological Storage

“…This investigation reveals the dissolution of various sandstone minerals, encompassing carbonate minerals, chlorite, and a minor fraction of feldspars. Li et al [21] employed modeling techniques involving PHREEQC calculations to investigate the interaction dynamics between the liquid phase and rock strata. Their analyses indicated that with the increase in burial depth (pressure), Ca 2+ can form calcite to facilitate precipitation.…”