CO2 Storage in Low Permeable Carbonate Reservoirs: Permeability and Interfacial Tension (IFT) Changes During CO2 Injection in an Iranian Carbonate Reservoir

Abstract

The lack of fundamental experimental studies on low permeable carbonate reservoirs for CO₂ sequestration purposes is essential for further application of CO₂ sequestration as a highly-anticipated CO₂ mitigation method in deep saline aquifers, specifically those with low permeabilities. The core samples were taken from a carbonate reservoir in Iran and the brine composition was based on that of the same formation. The objective of this study is to investigate permeability alteration during CO₂ sequestration in the aquifers of a low permeable Iranian carbonate reservoir. Various parameters have been investigated. The effects of different parameters such as injection pressure, confining pressure, and temperature on permeability alteration of the cores was investigated. Moreover, the interfacial tension (IFT) of CO₂/brine was also determined at pressures and temperatures up to 7 MPa and 100 °C, respectively. The experimental results showed CO₂ solubility and rock dissolution to be the governing mechanism when CO₂ was injected into carbonate cores. The permeability measurements showed that permeability increases by increasing injection pressure and decreases by increasing confining pressure and temperature. The IFT measurement results showed that the IFT decreases significantly when there is an increase in pressure and temperature.