Date of Award

2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

R.D. LeFever

Abstract

The Three Forks Formation of the Williston Basin in northwestern North Dakota is an Upper Devonian stratigraphic unit unconformably overlain by the Bakken Formation. It consists principally of dolostone, shale and anhydrite. The Three Forks is a productive tight oil resource play, which in recent years has been increasingly targeted and developed as part of the unconventional Bakken Petroleum System. Core analysis via energy dispersive x-ray fluorescence (ED-XRF) is a non-destructive, high-resolution chemostratigraphic data collection method that has been used here to produce concentration logs which reflect both lithologic heterogeneity and paleoredox conditions for the Three Forks Formation. These geochemical analyses are compared with detailed core descriptions, lithofacies identifications and subsurface maps generated on the basis of tops picked from wireline logs. Such comparisons show that every major stratigraphic surface within the Three Forks Formation is discernable on the elemental chemostratigraphic curves produced in this study. The elemental concentration logs are further used to discuss chemostratigraphic “packages” which are made up of consistently observed, correlatable trends in elemental geochemistry.

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