OIl and Gas Evalualtion

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illustration of oil pump

In northeastern Montana, drilling activity is increasing again, and the Bakken oil play is rapidly expanding into Roosevelt and Sheridan Counties. Horizontal drilling and fracture stimulation play a critical role in the successful production of Montana's largest oil reservoir. The MBMG continues to be involved with the petroleum industry, providing geologic data, maps, and other information to individuals, public agencies, and industry. As an example, the MBMG has worked closely with coalbed methane (CBM) producers over the past decade to help manage and monitor co-produced water from CBM wells.

Possible impacts to the Fox Hills–Hell Creek aquifer resulting from the current energy development in eastern Montana and North Dakota are being evaluated through a computer-generated groundwater model. The MBMG and scientists from Idaho National Laboratories started working jointly on this 3-year project in spring 2012. Recently collected data show substantial water-level declines in this important aquifer. In some cases this decline has left ranchers without stock water. Numerous wells completed in the Fox Hills–Hell Creek aquifer are being used to supply industrial water for hydraulic fracturing. The modeling efforts will be used to replicate the current conditions and simulate the aquifer’s response to predicted increases in water use. The MBMG/INL team is also coordinating their efforts with USGS and the North Dakota State Water Commission through monthly phone conference meetings and a data-sharing website.

Impacts of Oilfield Development to Water Resources in Eastern Sheridan County

The MBMG has worked with the U.S. Geological Survey and the U.S. Fish and Wildlife Service documenting impacts of oil development on water resources. The work has documented contamination from water co-produced with hydrocarbons. Ongoing work has influenced handling of production water 10 times as salty as sea water. A Contamination Index developed by the MBMG over 20 years ago uses field values to determine the ratio of CL/SC. CI ratios greater than 0.035 typically indicate contamination from water co-produced with hydrocarbons. Recently completed projects have documented wetlands, lakes, and groundwater contaminated by oilfield wastes.


For more information on regulations contact the
Montana Board of Oil and Gas Conservation