Abstract

Geologic carbon storage is one of the promising methods to reduce atmospheric carbon dioxide (CO2) concentration. Successful injection and storing of supercritical CO2 (scCO2) in geologic formations requires prediction of invasion behavior of scCO2 because it determines the efficiency of capillary trapping (or residual trapping). We investigated the invasion behavior of scCO2 in a brine-saturated sandstone using pore network modeling. The pore network was generated by using microCT imageries of a sandstone from the Domengine formation that is considered as a potential candidate site for geologic CO2 storage. Then, scCO2 injection to the brine-saturated pore network was simulated by applying the constant pressure difference between the inlet and outlet. This study presents the distribution of invaded scCO2 in the pore network, followed by the discussion on the residual saturations of scCO2 and brine at various differential pressure.

1. Introduction

Pore network modeling have been used to predict microscopic behavior of multi-phase flow in porous media. For geological storage of CO2, understanding and prediction of multi-phase flow behavior of scCO2 is fundamental to predict the efficiency and integrity of CO2 storage because the residual trapping (or capillary trapping) plays a significant role in immobilization of scCO2.

In this study, we investigated the invasion behavior of scCO2 in a brine-saturated sandstone using pore network modeling. While flow experiments with scCO2 appears to be challenging due to high pressure and temperature conditions and low repeatability, two-phase flow simulation using the pore network modeling was performed to explore scCO2 distribution in porous media during and after scCO2 injection. The pore network, which is a network consisting of cylindrical pore throats and spherical pore chambers, was reconstructed by using microCT imageries of a Domengine sandstone. Then, scCO2 injection to the brine-saturated sandstone was simulated by applying the constant pressure difference between the inlet and outlet. The distributions of invaded scCO2 in the pore network were presented, and the discussion on the residual saturations of scCO2 and brine at various differential pressure followed.

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