Case Study of Site Characterization and Remedial Plans for Removal of Contamination from Oilfield Produced Waters, East Poplar Oil Field, Fort Peck Indian Reservation, Roosevelt County, Montana

Michael Jacobs¹, Christa Tyrell², and Bruce Smith^3
1Pioneer Natural Resources USA, Inc, Midland, TX
²OEP Division of Water Quality, Fort Peck Assiniboine & Sioux Tribes, Poplar, MT
³United States Geological Survey, Denver, CO

The shallow aquifer(s) in this region has been heavily impacted by produced water from historical oil and gas operations. One identified point source of contamination was a plugged and abandoned production well operated by Mesa Petroleum, the Mesa Biere #1-22. The well was originally plugged in 1986 but was improperly plugged and released chloride-rich oilfield brine into the shallow aquifer. Parker and Parsley Oil and Gas Company merged with Mesa Petroleum in August 1997 to form Pioneer Natural Resources USA, Inc (PNR).

The results of an investigation conducted by PNR from 1999-2000, indicated that the wellbore was leaking outside of the casing at around 1,000 feet below ground and was channeling into the shallow aquifer at approximately 40 feet below the ground surface. Further studies in 2006 involved a detailed study of the regional geological and hydrological setting of the contaminant plume from the Biere #1-22 well. Geologically, the Biere #1-22 contaminant plume is located within a discrete, coarse-grained, gravel channel directly overlying the Cretaceous Bearpaw Shale and is separated geologically and hydraulically from other contaminant plumes in the area. PNR characterized the aquifer, conducted groundwater modeling, identified plume capture and containment zones and has drilled a deep (7,800 + foot) injection well and six shallow brine recovery wells for the capture and removal of the contaminated groundwater.

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