Shallow Natural Gas Occurrences in Quaternary Deposits in North Dakota
Fred J. Anderson1, John P. Bluemle2, David W. Fischer3, and Edward C. Murphy1
1 North Dakota Department of Mineral Resources, Bismarck, ND
2 Minerals Diversified Services, Bismarck, ND
3 Fischer Oil and Gas, Inc, Grand Forks, ND
Shallow natural gas occurs within several near surface geologic environments in North Dakota. Occurrence has been observed or inferred to originate within glacial sediments accumulating as the result of glaciotectonic processes and anthropogenic means. Historically, gas has been produced from fields in Renville and Bottineau Counties. Geologic conditions and potential sourcing consist of a subcrop of Cretaceous marine sediments scoured and mantled by glacial sediments with contained organics as a potential source. Glaciotectonic ice-thrust masses, several square kilometers in areal extent, and structures within Cretaceous units, may impose structural control on shallow subsurface fluid flow. The advance and retreat of glacial ice across the northern Great Plains and subsequent sediment unloading may influence development of horizontal partings and vertical fracturing within glacial sediments and underlying sedimentary strata providing conduits for shallow gas flow. Gas-rich deposits of sodium sulfate up to 80 feet thick beneath 15 playa lakes in northwestern North Dakota consist primarily of black, organic-rich clays and crystalline layers of sodium sulfate of Holocene age. Borehole gas emanations and gas pockets beneath salt layers were observed along with gas escaping from vents on the bottom of Miller Lake in Divide County. Anthropogenic methane generation within landfills occurs in Minot, Harvey, Williston, Grand Forks, and Hillsboro representing a local gas resource with more than 400 cfm of gas extracted from a recently installed gas collection system in Fargo. Over 300 MCF of gas has been used locally, since system construction, as an alternative industrial fuel source.