WorldOil

Helicopter survey aids remediation of produced water-contaminated aquifer

Airborne surveys mapped conductivity to help USGS researchers find areas of high salinity in and near East Poplar oil field in northeastern Montana. Beginning in 1976, the US Geological Survey (USGS) has assessed and mapped groundwater resources at the Fort Peck Indian Reservation. Results of these studies have demonstrated that groundwater quality has been adversely affected by various land-use practices in some areas of the reservation.1 Groundwater plumes of saline water were identified in 1997 based on water well sampling, ground geophysical surveys and borehole logs.2 USGS determined that these plumes were related to handling and disposal of brine produced with oil from East Poplar Field. In August 2004, a Helicopter ElectroMagnetic (HEM) survey was conducted over the oil field to better define possible subsurface plumes. The airborne EM measurements greatly expanded data collected from previous ground EM surveys and have helped USGS to understand the sources of anomalies and to define possible flow paths.