U.S. GEOLOGICAL SURVEY NATIONAL GEOLOGIC CARBON DIOXIDE SEQUESTRATION ASSESSMENT

The U.S. Geological Survey (USGS) has a long history of assessing national and global ground- and surface-water resources and geologically based energy and mineral resources. In 2007, the Energy Independence and Security Act (Public Law 110–140) authorized the USGS to conduct a national assessment of geologic storage resources for carbon dioxide (CO₂) in consultation with the U.S. Environmental Protection Agency, the U.S. Department of Energy (DOE), and State geological surveys. An initial step in this process was to develop a methodology to estimate the CO₂ storage resource potential that can be uniformly applied to geologic formations across the United States. After extensive peer, public, industry, and academic review, a final assessment methodology report (Brennan and others, 2010, http://pubs.usgs.gov/of/2010/1127) was published in June, 2010, and will be the probability based methodology used by the USGS to assess the Nation’s geologic storage resources for CO₂.

A team of USGS geologists working with State geologic surveys, and other State and Federal agencies, will delineate storage assessment units (SAU) and estimate CO₂ sequestration capacity in buoyant and residual storage traps within each assessed basin. SAUs will (1) be composed of a storage formation and an overlying seal which prevents CO₂ migration out of the storage unit; (2) be located at depths of 3,000 to 13,000 ft (914 to 3,962 m) to ensure that CO₂ is in a supercritical state (upper depth limit) and can be injected at pipeline pressures (lower depth limit); and (3) contain no formation water with total dissolved solids >10,000 parts per million (ppm) to prevent contamination of potential potable water. Assessment results will be compiled and released as a USGS publication in 2013.