Abstract

The U.S. Geological Survey, in accordance with the Energy Independence and Security Act of 2007, developed a methodology to estimate storage potential that could be applied uniformly to geologic formations across the United States. An initial methodology was developed and published in March 2009 (Burruss and others, 2009), and public comments were received. The report was then sent to a panel of experts for external review.

This current report is in response to those external comments and reviews and describes the revised methodology. The resource that is assessed is the technically accessible storage resource, which is defined as the mass of CO₂ that can be stored in the pore volume of a storage formation. The methodology that is presented in this report is intended to be used for assessments at scales ranging from regional to subbasinal in which storage assessment units are defined on the basis of common geologic and hydrologic characteristics. The methodology does not apply to site-specific evaluation of storage resources or capacity. Calculations of subsurface pore volume for potential CO₂ storage have been described in a number of publications (Bachu, 2003; Bradshaw, 2004; Bachu and others, 2007; U.S. Department of Energy, National Energy Technology Laboratory, 2008; van der Meer and Egberts, 2008). The methodology in this report is different in that it uses fully probabilistic methods to incorporate geologic uncertainty in calculations of storage potential.