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, Tyrell Christa², and Bruce Smith^3
1Environmental, Pioneer 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 appeared to have been improperly plugged and had 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). PNR was first notified of this well in 1999.

The results of an investigation conducted by PNR in 1999-2000, indicated that the wellbore was leaking outside of the casing in the Cretaceous, Judith River Formation at around 1,000 feet below ground and was channeling into the shallow aquifer at approximately 40 feet below the ground surface. Some evidence of this was that in this area the natural ambient groundwater temperature is around 45 degrees Fahrenheit. However, in the immediate vicinity of the Biere #1-22 well the groundwater temperature was as high as 200 degrees Fahrenheit with chloride concentrations as high as 44,700 mg/L. PNR drilled three relief wells adjacent to the old wellbore and successfully sealed the wellbore.

In 2006 PNR began a detailed study to characterize both the regional geological and hydrological setting of the oilfield contamination as well as the contaminant plume from the Biere #1-22 well. Importantly, the study showed that the Biere #1-22 contaminant plume was located within a discrete, coarse-grained, gravel channel directly overlying the Cretaceous Bearpaw Shale that is separated both geologically and hydraulically from the other contaminant plumes in the area.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas