Evaluating Technologies Designed to Reduce Carbon Emissions

Power plants, refineries, and chemical operations emit large amounts of carbon dioxide into the atmosphere, which has led to efforts to control these sources of greenhouse gas emissions. Battelle scientists have recently undertaken the challenge of evaluating methods to reduce or eliminate carbon emissions, as part of ongoing projects funded by the U.S. Department of Energy (DOE) and several industrial clients. They are using sophisticated reservoir modeling techniques to simulate the injection of carbon dioxide into deep rock formations, so that they can assess the potential for geologic sequestration (removal or separation) of greenhouse gases. The process involves capture/separation of carbon dioxide from flue gases and compression into a supercritical liquid - one that has physical and chemical properties intermediate between those of liquids and gases - that may then be injected into wells drilled into deep rock formations. Petroleum reservoir models were customized to assess the storage capacity of deep rock formations.

The models simulated the movement of the carbon dioxide in the formations, interaction with formation fluids (brines present in the rock), and hydraulic impact of the injection system. To address the different phases of the liquid involved in the technology, the model was extensively modified in collaboration with the University of Texas at Austin. Initial calculations show that several percent of the injected carbon dioxide would dissolve into formation fluids. Because the supercritical carbon dioxide is lighter than formation brine, the remaining liquid would move upward as a separate phase until it encountered the confining layers that retain the carbon dioxide in the deep formations and prevent leakage into shallow aquifers. Over time, most of the injected fluid would gradually dissolve into the highly saline brines present in the rock formations.

The figures above show the simulated pressure and saturation of carbon dioxide around the injection well at depths of several thousand feet. Pressure increases in an inverted cone shape around the injection well. Carbon dioxide saturation distribution reflects the upward migration of the injected fluid. The modeling demonstrated the potential for geologic sequestration of greenhouse gases and has helped move the technology toward field-scale applications. Battelle is now developing and using simulation codes to design a large-scale field demonstration facility.

For more information on Battelle's carbon sequestration modeling, contact Dr. Neeraj Gupta at (614) 424-3820, gupta@battelle.org.