HR: 17:00h
AN: H32G-05    [PDF]
TI: Organic Compounds in Produced Waters From Coalbed Methane Wells in the Powder River Basin, WY
AU: * Orem, W
EM: borem@usgs.gov
AF: U.S. Geological Survey, 956 National Center, Reston, VA 20192 United States
AU: Lerch, H
EM: tlerch@usgs.gov
AF: U.S. Geological Survey, 956 National Center, Reston, VA 20192 United States
AU: Rice, C
EM: crice@usgs.gov
AF: U.S. Geological Survey, Box 25046 Federal Center MS 973, Denver, CO 80225 United States
AU: Tatu, C
EM: dns@mail.dnttm.ro
AF: County Hospital Timisoara, Clinical Laboratory No. 1 Str. L. Rebreanu 156, Timisoara, RO-1900 Romania
AB: Coalbed methane (CBM) is a significant energy resource, accounting for about 7.5% of natural gas production in the USA. The Powder River Basin (PRB), WY is currently one of the most active CBM drilling sites in the USA. One aspect of concern in the exploitation of CBM resources is the large volumes of water recovered from wells along with the natural gas (so-called produced waters). CBM produced waters may contain coal-derived dissolved substances (inorganic and organic) of environmental concern, and a potential disposal problem for CBM producers. Studies of CBM produced water have mostly focused on inorganics. Dissolved organic compounds in CBM produced water may also present an environmental issue, but little information is available. As part of a larger study of the health and environmental effects of organic compounds derived from coal, we analyzed a number of produced water samples from CBM wells in the PRB, WY for dissolved organic substances. Our goals were to: (1) create an initial dataset on organic compounds in produced waters, and (2) integrate these results with our existing results on coal-derived organic compounds in the environment to evaluate potential health and environmental impacts. In 2001, we sampled produced water from 13 CBM wells covering a broad area of the PRB in order to identify and quantify the organic compounds present. In 2002, produced water from 4 of the 2001 CBM wells and 8 new CBM wells were sampled for dissolved organic components. Produced water was collected directly from each well and filtered on site. Organic compounds were isolated from produced water samples by liquid/liquid extraction with methylene chloride and identified and quantified by gas chromatography/mass spectrometry (GC/MS). Organic compounds identified by GC/MS in extracts of the produced water samples, included: phenols, biphenyls, N-, O-, and S-containing heterocyclic compounds, polycyclic aromatic hydrocarbons, phthalates, aliphatic hydrocarbons, and fatty acids. However, most compounds had structures unidentified by GC/MS databases. Many of the identified organic compounds (phenols, heterocyclic compounds, polycyclic aromatic hydrocarbons) are likely coal-derived. Concentrations of individual compounds ranged from about 10 to 0.01 $\mu$g/l. Some CBM wells with high concentrations of dissolved organic compounds present in 2001 had much lower concentrations in 2002, indicating temporal variability. Some of the organic compounds identified in the produced water samples are toxic (mutagenic and cancer promoters), but are unlikely to have acute health effects at the low levels present. Chronic health and environmental effects from long periods of low-level exposure, however, are possible. Continuing studies will expand the existing dataset on dissolved organic compounds in produced water, and evaluate the toxic effects of these compounds.
DE: 1055 Organic geochemistry
DE: 1831 Groundwater quality
SC: Hydrology [H]
MN: 2003 Fall Meeting