A demonstration site for geologic sequestration is in the phase of preinjection characterization and permitting. This site, located northeast of Houston, Texas, will provide the first onshore CO₂ sequestration field demonstration in a brine formation setting. Two idle wells in a historic oil field will be recompleted in a nonproductive Frio sandstone interval above production and below and hydrologically separated from potable water.

Team partners from the GEOSEQ project will conduct a series of field monitoring experiments before, during, and after CO₂ injection. These experiments will test the effectiveness of a spectrum of CO₂ monitoring techniques and compare methods and numerical models. The site provides for a rapid start-up using existing infrastructure and low risk of adverse impacts because the CO₂ will be injected into a hydrologically isolated reservoir compartment of a well-known geologic structure. Safety is implicit in the experiment design, which is focused on intensive monitoring. Additional safety will be provided by using contractors experienced in CO₂ injection and hazardous waste disposal.

Injection will be into a thin, relatively homogenous wave-reworked distributary channel/delta front sand of the upper Frio Formation beneath the thick Anahuac shale. Lateral migration of CO₂ will be limited by structural compartmentalization along faults associated with the setting on the flank of a salt dome. Characterization of the injection interval using a preexisting 18 mi² 3-D seismic survey and wireline well logs from 36 wells in the 1-mi² area provides input data for planning phase modeling. Extensive field-scale data, brine chemistry, and core available for the Frio Formation in the region are used to document petrophysical characteristics, mineralogy, and brine composition. A volume of CO₂ adequate to support the experiment will be trucked to the site.

Texas is the lead state in U.S. CO₂ emissions, and this project will demonstrate a mechanism for emissions reduction. This small-volume pilot will extend the demonstration of modeling and monitoring capabilities for sequestration into the geologic setting where very large scale sequestration is feasible in the geographic setting where sequestration is needed.