Recent climate change is attributed to carbon dioxide (CO2), the most common greenhouse gas. The U.S. emits over 6 billion tons of CO2 each year primarily due to the combustion of fossil fuels; 40 percent of this is for the generation of electricity. Utah, a major coal-producing state, depends on several coal-fired power plants within the state for over 80 percent of its electricity.
Geo-sequestration—long term storage in underground geologic formations—is one proposed way to reduce CO2 levels in the atmosphere. Demonstrating the ability to safely store CO2 deep underground may lead to development of commercial capture and long-term storage of greenhouse gases from large industrial plants, greatly reducing the volume of anthropogenic CO2 released into the atmosphere. Fortunately, Utah’s geology provides abundant potential for long-term storage of CO2 in deep, saline reservoirs and depleted to nearly depleted oil and gas fields.
Before the injection of CO2, it must be determined whether an area is geologically suitable for sequestering CO2. Faults or other fractures occurring in strata of the area can be potential migration pathways for CO2 to leak from the reservoir to the surface. The surface geology must be mapped to determine if any faults or fracture systems are present within surface formations. Then subsurface formations must also be mapped by focusing on groundwater aquifers, the oil reservoir, and the reservoir seal to determine if any faults are present at depth.
The reservoir seal is an impermeable layer above the reservoir that keeps reservoir fluids from migrating to the surface. If any surface faults link with subsurface faults cutting the reservoir seal or reservoir, then CO2 could migrate or leak to the surface. Or, if any faults connect the reservoir to the groundwater aquifers, then this could lead to CO2 contamination of aquifers that are critically important to the local communities.