GRAND FORKS – The North Dakota Geological Survey is working to take the temperature of the Williston Basin. Temperature data scientists have about the Bakken and other areas below the surface is questionable, said geologist Stephan Nordeng. “Right now we’re relying on data that’s mostly unreliable,” Nordeng said. A research project Nordeng is leading seeks to develop temperature profiles of 12 to 15 abandoned oil wells in western North Dakota. Accurate temperature information is important for several applications, including designing fluid for hydraulic fracturing, determining how much oil is in place, and exploration of oil and gas, Nordeng said. Knowing heat flow values also is important for determining geothermal resources, he said. Lynn Helms, director of the Department of Mineral Resources, asked companies during the North Dakota Petroleum Council’s annual meeting in Grand Forks to work with the Geological Survey on the research.
The research will include studying at least one test well in northeast McKenzie County, an area that recently has seen some record-setting oil wells. The state has subsurface temperature information from some shallow wells, but no one has ever accurately measured the temperature as deep as 9,000 to 11,000 feet below the surface, Nordeng said. Measuring the temperature of a well that is recently drilled is unreliable because factors such as pumping cold fluid in the well cools the wellbore off while grinding up the rock heats it up.
“There’s no real good way of measuring temperature from a well that’s just drilled,” he said. “Rock takes a long time to equal out to temperature.” To get more accurate temperature data, the research will focus on temporarily abandoned wells, or wells that were formerly in production but the company abandoned them and chose not to plug them because they may come back and use them in the future. The temperature of the Bakken in the Watford City area, which is considered the most mature area of the Bakken, is estimated to be slightly above the boiling point of water, or between 150 degrees and 220 degrees Fahrenheit, Nordang said. After the first phase of the project, researchers plan to look at 100 other wells, which could include water wells, to get additional information.