TY - JOUR
T1 - Organic substances in produced and formation water from unconventional natural gas extraction in coal and shale
AU - Orem, William
AU - Tatu, Calin
AU - Varonka, Matthew
AU - Lerch, Harry
AU - Bates, Anne
AU - Engle, Mark
AU - Crosby, Lynn
AU - McIntosh, Jennifer
N1 - Funding Information:
Support for this work was provided by the USGS Energy Resources Program (B. Pierce, Program Coordinator) . Many thanks to Melissa Schlegel and Brittany Bates (Univ. of Arizona) who collected a number of the produced water samples from the New Albany Shale, and the Illinois and Williston Basins CBM. Work in the Black Warrior Basin was conducted in cooperation with the Geological Survey of Alabama, and supported by the U.S. Department of Energy , National Energy Technology Laboratory , under contract DE-FE0000888 . We thank several private CBM and shale gas producers from across the USA for providing access to their wells for collecting produced water samples. Trade names used in this report are for the purpose of full disclosure of analytical methods; no endorsement of any commercial product by the U.S. Geological Survey is implied.
PY - 2014/6/1
Y1 - 2014/6/1
N2 - Organic substances in produced and formation water from coalbed methane (CBM) and gas shale plays from across the USA were examined in this study. Disposal of produced waters from gas extraction in coal and shale is an important environmental issue because of the large volumes of water involved and the variable quality of this water. Organic substances in produced water may be environmentally relevant as pollutants, but have been little studied. Results from five CBM plays and two gas shale plays (including the Marcellus Shale) show a myriad of organic chemicals present in the produced and formation water. Organic compound classes present in produced and formation water in CBM plays include: polycyclic aromatic hydrocarbons (PAHs), heterocyclic compounds, alkyl phenols, aromatic amines, alkyl aromatics (alkyl benzenes, alkyl biphenyls), long-chain fatty acids, and aliphatic hydrocarbons. Concentrations of individual compounds range from <. 1 to 100. μg/L, but total PAHs (the dominant compound class for most CBM samples) range from 50 to 100. μg/L. Total dissolved organic carbon (TOC) in CBM produced water is generally in the 1-4. mg/L range. Excursions from this general pattern in produced waters from individual wells arise from contaminants introduced by production activities (oils, grease, adhesives, etc.). Organic substances in produced and formation water from gas shale unimpacted by production chemicals have a similar range of compound classes as CBM produced water, and TOC levels of about 8. mg/L. However, produced water from the Marcellus Shale using hydraulic fracturing has TOC levels as high as 5500. mg/L and a range of added organic chemicals including, solvents, biocides, scale inhibitors, and other organic chemicals at levels of 1000. s of μg/L for individual compounds. Levels of these hydraulic fracturing chemicals and TOC decrease rapidly over the first 20. days of water recovery and some level of residual organic contaminants remain up to 250. days after hydraulic fracturing. Although the environmental impacts of the organics in produced water are not well defined, results suggest that care should be exercised in the disposal and release of produced waters containing these organic substances into the environment because of the potential toxicity of many of these substances.
AB - Organic substances in produced and formation water from coalbed methane (CBM) and gas shale plays from across the USA were examined in this study. Disposal of produced waters from gas extraction in coal and shale is an important environmental issue because of the large volumes of water involved and the variable quality of this water. Organic substances in produced water may be environmentally relevant as pollutants, but have been little studied. Results from five CBM plays and two gas shale plays (including the Marcellus Shale) show a myriad of organic chemicals present in the produced and formation water. Organic compound classes present in produced and formation water in CBM plays include: polycyclic aromatic hydrocarbons (PAHs), heterocyclic compounds, alkyl phenols, aromatic amines, alkyl aromatics (alkyl benzenes, alkyl biphenyls), long-chain fatty acids, and aliphatic hydrocarbons. Concentrations of individual compounds range from <. 1 to 100. μg/L, but total PAHs (the dominant compound class for most CBM samples) range from 50 to 100. μg/L. Total dissolved organic carbon (TOC) in CBM produced water is generally in the 1-4. mg/L range. Excursions from this general pattern in produced waters from individual wells arise from contaminants introduced by production activities (oils, grease, adhesives, etc.). Organic substances in produced and formation water from gas shale unimpacted by production chemicals have a similar range of compound classes as CBM produced water, and TOC levels of about 8. mg/L. However, produced water from the Marcellus Shale using hydraulic fracturing has TOC levels as high as 5500. mg/L and a range of added organic chemicals including, solvents, biocides, scale inhibitors, and other organic chemicals at levels of 1000. s of μg/L for individual compounds. Levels of these hydraulic fracturing chemicals and TOC decrease rapidly over the first 20. days of water recovery and some level of residual organic contaminants remain up to 250. days after hydraulic fracturing. Although the environmental impacts of the organics in produced water are not well defined, results suggest that care should be exercised in the disposal and release of produced waters containing these organic substances into the environment because of the potential toxicity of many of these substances.
KW - Coal
KW - Natural gas
KW - Organic substance
KW - Produced water
KW - Shale
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U2 - 10.1016/j.coal.2014.01.003
DO - 10.1016/j.coal.2014.01.003
M3 - Article
AN - SCOPUS:84897045058
SN - 0166-5162
VL - 126
SP - 20
EP - 31
JO - International Journal of Coal Geology
JF - International Journal of Coal Geology
ER -