Date of Award

January 2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geological Engineering

First Advisor

Lance D. Yarbrough

Abstract

This research analyzed nine core sections representing The Lower Bakken and Three Forks Formation of the Williston Basin in North Dakota using x-ray fluorescence. The Charlotte 1-22H core sequence from Continental Resources was also included to assess the elemental composition of the stratigraphic interval spanning the Lodgepole, Bakken, Pronghorn, and Three Forks Formations. Core samples were obtained from the North Dakota Industrial Commission (NDIC) Wilson B. Laird Core and Sample Library at the University of North Dakota. Core sections were exposed to x-ray at 15 keV and 45 keV excitation voltages to provide elemental spectra; count rate values were obtained and elemental ratios were then calculated to assess the geochemical composition and diagenetic changes within each stratigraphic interval.

Results of x-ray fluorescence analysis of Williston Basin core included detailed well-logs showing the vertical distribution of lightweight, mid-range, and trace metal elements. The evidence collected in this research showed that x-ray fluorescence ratios can uniquely chronicle autonomous lithostratigraphic units with higher efficiency than conventional wireline or logging-while drilling technology. The x-ray fluorescence elemental ratios of Fe:Mn can more precisely determine formation contacts on core sections than conventional gamma ray or spontaneous potential methods. Furthermore, x-ray fluorescence will allow for unique identification of members and thin beds within larger formations. Elemental Ka fluorescence ratios of Fe:Mn, Fe:Ca, Fe:Rb, Fe:S, and S:Cl can precisely identify the Bakken Formation. Ratios of Ca:Mg, Ca:Rb, Ca:Zn, and Ca:Ti can precisely identify the Lodgepole, Three Forks, and Middle Bakken Formation. Furthermore, the ratio of Fe:Mn can be applied to the Middle Member of the Bakken Formation to identify unique lithofacies. This research only analyzed Williston Basin core, the results provided imply that calcium Ka fluorescence ratios can be used to identify any carbonate lithology; iron Ka fluorescence ratios can be used to identify any shale lithology.

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