The carbonic acid-rock reaction in feldspar/dolomite-rich tightsand and its impact on CO2-water relative permeability during geological carbon storage

Abstract

CO2 injection contributes to formation energy supplement to remedy the fast production decline in tight oil reservoir and CO2 storage at the same time.CO2 Here, we report CO2-water relative permeability with consideration of acid-rock reaction. The minerals of a tight rock sample were analyzed at first. CO2Then we established an experimental method to measure the relative permeability of CO2-water at reservoir conditions based on steady state method. After carbonic acid-rock reaction, the variation in rock mineralogy was compared. The pore size distribution in the rock sample was obtained by LF-NMR after dynamic corrosion at different pressure. Both small and large pore and throat were enlarged after corrosion. And the Klinkenberg permeability of tight sandstone was increased 7.4–18.8%. From the CO2-water relative permeability with corrosion, the irreducible water saturation was decreased for more than 15.1% in average, which indicates more flowing spaces for other fluids. In the two-phase flow regime, a good linear relationship was found between Krw/Krg and gas saturation in tight sand samples. It can be used for the estimation of relative permeability at different gas conditions.CO2CO2 Injection of CO2 in tight oil reservoir indicates improvement in EOR and GCS potential. Acid-rock reaction results in better fluid flow capacity for liquid and additional trapping of CO2.