Modeling of Interaction Between CO₂ and Rock in Core Flooding Experiments Available to Purchase

Understanding CO₂ (aq), mineral and water reactions is one of the key elements to long term CO2-storage in reservoirs. When CO2 is injected to reservoirs with water, CO₂ will be dissolved in the water phase. Liege outcrop chalk and Berea outcrop sandstone have been used as analogous to chalk reservoir and sandstone reservoir rocks to study interactions between CO₂ and rocks. Core flooding experiments have been conducted in these rocks at 340 bar 130°C with injection of formation water and carbonated water (CO₂-saturated formation water). The flow regime used was first injection of formation water follow by injection of carbonated water and a second injection of formation water. The sampling of the produced water phase was made at two different points after the core, high pressure and temperature (340 Bar and 130°C) and low pressure and temperature (2 Bar and room temperature). The samples were analysed for elements by Inductive Coupled Plasma (ICP). After the experiments, the numerical simulations were performed at the same conditions with two different geochemical softwares PHREEQC and TOUGHREACTS, to reproduce the experimental results. Using kinetic rates of the minerals, the numerical simulations were capable to show the dissolution and precipitation of carbonates minerals and formation of secondary minerals. The simulation results give a detailed understanding of the experimental geochemical system. It is concluded that the experimental and simulation methods can be used in combination to evaluate the potential for interactions between the rock and carbonated water. The compositions of effluent samples taken at high pressure have been found to be more representative than effluent samples taken at low pressure. The accuracy in the preparation of high pressure effluent samples should be improved.