Link Between CO2‐Induced Wettability and Pore Architecture Alteration

Abstract

AbstractChanges in pore (throat) size, surface roughness, and mineralogy induced by supercritical CO2‐water‐rock reactions impact petrophysical properties such as porosity, permeability, and especially wettability. Herein, we show that these changes directly impact relative permeability and capillary pressure curves, a fact rarely studied in the literature. In this work, we show that CO2 contact angle changes emerge after Madison Limestone samples were soaked for 400 hr in CO2‐enriched brine. Coreflooding results show that the water production rate and cumulative water production increased after the rock was exposed to carbonic acid. Moreover, the mercury capillary pressure decreased in mesopores and macropores, indicating the increase of size in these pores due to reactions. This compounded wettability and pore network alteration can directly affect CO2 injectivity, migration, and storage capacity. This fundamental insight into CO2 geological storage processes should aid practitioners to reduce uncertainties in forecasting CO2 distribution via injection simulation.