Center for experimental study of subsurface environmental processes

Projects - Geological Storage of Carbon Dioxide

Laboratory investigation of geological storage of carbon dioxide

One of the goals of this research is to understand the effect of natural geological heterogeneity on migration and stable entrapment of supercritical carbon dioxide (scCO2) within deep saline aquifers. In order to reproduce flow settings typical of depths >800 m we conduct displacement experiments in a variety of porous media with surrogate fluids at atmospheric conditions. X-ray attenuation analysis allows the quantification of spatial and temporal distribution of residually trapped pseudo-scCO2 within the reservoir.

Once entrapped in the reservoir pores, scCO2 dissolves in formation brine, and density-driven convective fingers are expected to be generated due to the higher density of the solution compared to resident brine, this phenomenon will eventually enhance dissolution of scCO2 into brine. The goal of this study is to evaluate the contribution of convective mixing to dissolution trapping of CO2 in naturally layered heterogeneous formations using surrogate test fluids and numerical modeling.

Another goal of this research is to better understand the fundamental processes involved with leakage of stored CO2 from geologic sequestration sites. If a failure occurs in the caprock above the storage formation or in the casing of a well that penetrates the storage formation, CO2 will leak upward toward the ground surface due to buoyancy. During leakage, the CO2 will dissolve into native groundwater and become diluted as the groundwater flows. As dissolved CO2 migrates, water pressure is likely to decrease and temperature to increase, potentially causing a separate gas phase to form. Understanding the spatiotemporal patterns of these processes is the first step towards developing risk assessment strategies for geologic CO2 sequestration projects. We conduct 1-D and 2-D laboratory experiments on multiple scales in order to investigate the evolution of gas phase CO2 from a dissolved source in porous media. Electrical conductivity measurements are used to track the migration of the dissolved CO2 plume, while saturation sensors are used to detect the formation, accumulation, and migration of gas phase CO2. The results of these experiments will be used to assess the ability of existing numerical models to capture the fundamental processes of CO2 evolution in the shallow subsurface.