CO2 storage in carbonate rocks: An experimental and geochemical modeling study

Abstract

Carbon dioxide storage in geological formations is one of the mature strategies developed for controlling global warming. This paper represents a comprehensive experimental and geochemical modeling study to analyze CO2-brine-rock interactions in a carbonate rock containing calcite and dolomite minerals. PHREEQC geochemical package has been applied for modeling the geochemical reactions in the studied porous media. Firstly, dynamic experiments are performed to calibrate the geochemical model. Then, static experiments are conducted to study the geochemical reactions in the CO2-brine-rock interaction system. This study contributes to analyzing the precipitation-dissolution and ion exchange mechanisms in the CO2-brine- carbonate rock reactions during carbon dioxide storage. The purpose of the present paper is providing a scientific basis to judge surface CO2 loading in carbonate reservoirs. Results of the present study show that brine-rock interaction increases the dissolution of carbon dioxide gas in the aqueous phase. It is also demonstrated that carbonate ions can attach to the minerals' surface through the ion exchange mechanism. Among the surface ion exchangers, >CaHCO3 contains the maximum amount of carbonate ion. At the high pressures, amount of the carbon dioxide stored on the minerals' surface is almost independent of the pressure variation.