A GIS-based vulnerability assessment of brine contamination to aquatic resources from oil and gas development in eastern Sheridan County, Montana

Risk assessment of brine contamination to aquatic resources from energy development in glacial drift deposits: Williston Basin, USA

“…Two surface water and two groundwater samples were collected in 2011 from 10 sections that spanned the range of SCA scores for a total of 37 samples. A complete description of the methods used to identify sampling locations for the SCA is provided in Preston et al (2014a). In 2012, the USGS collected a total of 123 surface water samples from 97 different sections to characterize water quality in the PPR of the Williston Basin.…”

“…The two sets of water samples were not combined to avoid potential confounding effects of interannual variations in water quality. Descriptions of the sampling methods and analytical techniques used to collect and analyze the SCA and regional characterization samples are provided in Preston et al (2014a) and Post van der Burg and Tangen (in press), respectively.…”

“…A large portion of the Prairie Pothole Region (PPR), an area containing millions of wetlands that provide critical habitat for the majority of North American migratory waterfowl (Batt et al, 1989), is located within these glacial deposits. Previous reports have documented brine contamination to aquatic resources (surface water and shallow groundwater) within the PPR and other glacial deposits that mantle the Williston Basin (Beal et al, 1987;Murphy, 1983;Murphy and Kehew, 1984;Murphy et al, 1988;Reiten and Tischmak, 1993;Thamke and Craigg, 1997;Peterman et al, 2010Peterman et al, , 2012Preston, 2011;Rouse et al, 2013;Preston et al, 2014aPreston et al, , 2014b. Much of the documented contamination is associated with older oilfield practices; however, spills of oil and brine continue to occur regularly.…”

“…A detailed description of contaminant sources and historical oilfield practices is provided in Preston et al (2014a) and summarized here. Leachates generated from now-buried reserve pits that were used to hold drilling fluids and brine are likely the most common source of contamination (Preston et al, 2014b).…”

“…In 2011, Preston et al (2014a) conducted an assessment of brine contamination to aquatic resources in eastern Sheridan County, Montana. The Sheridan County assessment (SCA) was conducted on the approximately 2.59 km 2 Public Land Survey System (PLSS) section grid and was based on the age and density of petroleum related wells (described as oil wells hereafter), surficial geology, and surface water features.…”