The Frio Brine Pilot experimental site is 30 miles northeast of Houston, in the South Liberty oilfield. Researchers at the University of Texas at Austin's Bureau of Economic Geology drilled a 5,753 foot injection well earlier this year, and developed a nearby observation well to study the ability of the high-porosity Frio sandstone formation to store carbon dioxide.
The carbon dioxide was injected into a zone from 5,053 to 5,073 feet below the surface into a brine-rock system contained within a fault-bounded compartment with a top seal of 200 feet of Anahuac shale. Injection began on October 4, and ran for 9 days. The site is representative of a very large volume of the subsurface from coastal Alabama to Mexico, and will provide experience useful in planning carbon dioxide storage in high-permeability sediments worldwide.
Extensive methods are being used to monitor the movement of the carbon dioxide. Before injection, baseline aqueous geochemistry, wireline logging, cross-well seismic, cross-well electromagnetic imaging, and vertical seismic profiling, as well as two well hydrologic testing, surface water, and gas monitoring were all completed. The monitoring was being repeated at intervals during the injection, and is continuing.
The region's subsurface is well known. Carbon dioxide has been successfully injected in the region for enhanced oil recovery, and fluid injection for waste disposal is widely accepted. However, modeling by Lawrence Berkeley National Laboratory has identified some poorly known variables that control carbon dioxide injection and post-injection migration. Measurements made during this field test will help to define the correct value for these variables, and will enable researchers to better conceptualize and calibrate models to plan, develop, and effectively monitor larger-scale, longer-timeframe injections.
The project is funded by the U.S. Department of Energy's Office of Fossil Energy and is managed by the National Energy Technology Laboratory. The Bureau of Economic Geology, Jackson School of Geoscience at the University of Texas, Austin is the lead project partner. Other project partners include:
Follow-on testing with longer-term monitoring and a larger volume of CO2 is planned to determine the formation's capacity to store CO2 and to identify any potential environmental impacts. Planning for this larger-scale project is a major task of the Gulf Coast Carbon Center, a regional industry-academic partnership that is working to develop economically viable, environmentally effective options for reducing carbon emissions. The Gulf Coast Carbon Center is also a partner in DOE's Southeast Regional Carbon Sequestration Partnership.
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