From Bureau of Economic Geology, The University of Texas at Austin (
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2004 GSA Annual Meeting, Denver, Colorado, November 7–10, 2004

Frio Brine Pilot Experiment—Update and Preliminary Results

Susan D. Hovorka


The Frio Brine Pilot experiment site is 30 mi (50 km) northeast of Houston, Texas, USA, in a historic oilfield. The selected subsurface the test interval is 70-ft- (21-m-) thick, mineralogically complex, reworked fluvial sandstone of the upper Frio Formation of Oligocene age. Average porosity in injection sandstone measured using a neutron porosity log is 27%, and measured permeability is 150 to 3,000 md. The sandstone test interval is isolated by numerous thick shales above and below the interval and fault compartmentalization on the sides. CO2 is injected into a zone at depths of 5,050 to 5,080 ft (1,539 to 1,548 m) below surface—a brine-rock system with no hydrocarbon accumulation. Dip in the injection sandstone is steep, about 16° toward the south.

The Frio Brine Pilot experiment is designed to field test modeling, monitoring, and verification techniques using baseline wireline logging, aqueous geochemistry, crosswell seismic and vertical seismic profiling, hydrologic testing, and surface water and gas monitoring which are then repeated following a September injection test using 3,000 tons of refinery CO2. Nine companies and research institutions have collaborated to field the experiment. Detailed reservoir characterization and modeling has been an intrinsic element throughout project design, implementation, and interpretation.

The site is representative of a broad area that is an ultimate target for large-volume storage because it is part of a thick, regionally extensive, thick sandstone trend that underlies a concentration of industrial sources and power plants along the Gulf Coast of the United States. Development of geologic storage in this region has excellent potential to upscale to impact U.S. releases.

To move toward a larger scale, longer time CO2 storage experiment, an industry-academic partnership, the Gulf Coast Carbon Center, an initiative of the Jackson School of Geosciences, is working to develop economically viable, environmentally effective options for reducing carbon emissions in the region. Goals include developing a vision for how sources and sinks can be aggregated to form a network for capture and storage and to develop a first project that is likely to match a hydrogen or ethylene oxide plant with a reservoir that will be used for CO2-enhanced oil production plus storage.