Date of Award

2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

W. Gosnold

Abstract

Understanding the thermal regime of a large intracontinental basin such as the Williston Basin can be enhanced by analysis of the relationships among radiogenic heat production, surface heat flow, formation temperatures, and gravity and magnetic anomaly patterns. Digital processing of the spatial and causal relationships gives insight into the effect of basement heat production on the thermal state of the basement rocks and the overlying sedimentary successions. These relationships provide valuable insight on the radioactive heat contribution to heat flow, heat flow from the lower crust, composition of the upper crust, and the potential for geothermal power generation. The specific data used in this study include: radiogenic heat production values from well logs penetrating the Precambrian basement of the Williston basin in North Dakota, heat production values from gamma ray spectrometry on Precambrian basement core, tens of thousands of formation temperatures from the National Geothermal Data System borehole temperature data set, gravity and magnetic data (processed to generally characterize thickness and lithology of the radioactive layer), and stratigraphy and lithology.

Surface heat flow in the Williston basin cannot be predicted strictly by inputs from the mantle and from the radiogenic basement heat. The direct influence of basement heat production on heat flow through the sedimentary succession is visible for deeper units, but shallow and surface heat flow is perturbed by advection in younger aquifers. While potential for enhanced geothermal systems (EGS) and sedimentary enhanced geothermal systems (SEGS) as well as co-produced and low temperature geothermal are ultimately controlled by temperature, understanding basement radioactivity can provide insight for delineating exploration areas.

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