While advances in hydraulic fracturing technology have resulted in an oil and gas boom in North Dakota and other parts of the U.S., the industry, federal and state regulators, and local communities have also had to contend with outgrowths of that development. One particular issue confronting those groups is how to handle and dispose of wastewater.
To that end, the U.S. Geological Survey (USGS) recently developed a system that may help prevent some brine contamination in wetlands and groundwater that could potentially accompany oil and gas development. Brine is a form of wastewater that occurs naturally and is often extracted along with oil and gas in parts of the Williston Basin and Bakken formation, which includes parts of North Dakota, Montana, and Canada.
In the study, which is part of a larger USGS project on brine contamination in the Williston Basin, the USGS scientists developed a system for evaluating brine contamination risk by assessing five variables: the percent of land that is wetlands; the percent of land that is glacial outwash; a highly permeable geology; the total length of streams; the age of the oldest well; and the number of wells. That assessment is used to compute a contamination vulnerability score. When compared to groundwater and surface water samples in Sheridan County, Montana—on that state’s border with North Dakota—the scoring system correlated with brine contamination throughout the sample area; places with low contamination levels had low vulnerability scores and places with high contamination levels had high vulnerability scores.
This analytical tool could help the oil and gas industry, as well as landowners and regulators, identify and avoid storing wastewater in those areas with high potential for brine contamination as they proceed with development efforts going forward. It may be especially helpful in North Dakota where a review last year found more than 2.3 million gallons of saltwater had spilled in the state over a 22-month period.
In another study that’s currently underway, the U.S. Environmental Protection Agency (EPA) is reviewing the potential impacts of hydraulic fracturing on drinking water resources. And wastewater treatment and disposal is among those potential impacts the EPA is researching as part of the overall study. The EPA expects to release a draft report on its study later this year.
Ideally, these efforts will help the oil and gas industry continue its development expansion throughout the Williston Basin and elsewhere, while at same time providing ways to better preserve water resources.