&EPA Office of United States Ground Water and Environmental Protection Agency Drinking Water CLASS V UIC STUDY FACT SHEET IN-SITU FOSSIL FUEL RECOVERY WELLS What is an in-situ fossil fuel recovery In-situ fossil fuel recovery wells are used to facilitate in-situ conversion of a hydrocarbon well? resource into a gaseous or liquid form that can be extracted through production wells. Specifically, in-situ fossil fuel recovery wells are used to initiate and then to maintain and control combustion through injection of gases or ignition agents. There are three types of processes that may use in-situ fossil fuel recovery wells: in-situ combustion of tar sand deposits, underground coal gasification, and in-situ oil shale retorting. In-situ combustion of tar sand deposits has not been employed in the United States. What types of fluids are injected into The injectate may include air, oxygen, steam, carbon dioxide, or ignition agents, in-situ fossil fuel recovery wells? Do injectate constituents exceed Most of the injected materials are gases that are not likely to show exceedances of drinking water standards at the point drinking water standards or health advisory levels. When ignition agents such as of injection? ammonium nitrate are injected, exceedances of drinking water standards and health advisory levels would be expected, but has not been documented. What are the characteristics of the In-situ fossil fuel recovery wells inject into a hydrocarbon-containing unit, which is often injection zone of an in-situ fossil fuel a steeply inclined coal seam or oil shale deposit that is not practical to mine with recovery well? conventional methods. Although injected gases generally do not introduce contaminants into the subsurface, injection may alter the characteristics of an underground source of drinking water (USDW), if the gases are allowed to contact a USDW, by changing the USDW's temperature or increasing the level of gas saturation. Contamination of ground water resulting from in-situ fossil fuel recovery operations is well documented, to the extent that most, if not all, in-situ fossil fuel recovery operations initiated in the last 20 years appear to have caused some ground water contamination. The ground water is not contaminated with the injected materials, however. Rather, it is contaminated with combustion byproducts, such as benzene. At some sites, water containing benzene and other combustion byproducts, such as phenols, has migrated via fractures or other means from the reaction zone into nearby ground water. Are in-situ fossil fuel recovery wells Overall, in-situ fossil fuel recovery wells are not likely to receive spills or illicit vulnerable to spills or illicit discharges. The observed contamination problems are associated with in-situ fossil fuel discharges? recovery operations, rather than rare spills or accidents. How many in-situ fossil fuel recovery There are no known active in-situ fossil fuel recovery wells in the United States. wells exist in the United States? Where are in-situ fossil fuel recovery As stated above, there are no active in-situ fossil fuel recovery wells in the United States. wells located within the United States? In the past, such wells have operated primarily in WY and CO. How are in-situ fossil fuel recovery Individual permit: WY, CO wells regulated in states with the largest number of this type of well? Where can I obtain additional For general information, contact the Safe Drinking Water Hotline, toll-free 800-426- information on in-situ fossil fuel 4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding recovery wells? federal holidays, from 9:00 a.m. to 5:30 p.m. Eastern Standard Time. For technical inquiries, contact Amber Moreen, Underground Injection Control Program, Office of Ground Water and Drinking Water (mail code 4606), EPA, 401 M Street, SW, Washington D.C., 20460. Phone: 202-260-4891. E-mail: moreen.amber(@epa.gov. The complete Class V UIC Study (EPA/816-R-99-014, September 1999), which includes a volume addressing in-situ fossil fuel recovery wells (Volume 13), can be found at http://www.epa.gov/OGWDW/uic/cl5study.html. Are there any contamination incidents associated with in-situ fossil fuel recovery wells? ------- |