Date of Award

January 2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Petroleum Engineering

First Advisor

Mehdi Ostadhassan

Abstract

The Bakken Shale samples were analyzed by utilizing several techniques including AFM-based Nano-IR spectroscopy, Rock-Eval 6, XRF, NMR spectroscopy, VRO, and organic petrography using reflected white light and UV light for understanding chemistry of organic matter (OM). Organic petrography showed that OM consists of various types of solid bitumen (SB), matrix bituminite, acanthomorphic acritarch, marine alginite, micrinite, and inertinite macerals. Liptinite fluorescence color was used to confirm the thermal maturity level. The results indicate that kerogen is mainly marine Type II. The original hydrogen index was restored using various mathematical/empirical methods. It was found that organofacies ‘B’ is the most abundant organofacies present in the Bakken Shale.

The Bakken was missing an independent correlation of Tmax with VRO. This study showed that linear trends cannot accurately represent the relationship between these two parameters, considering the kerogen kinetics and non-linear relationship between transformation ratio and Tmax. Therefore, a polynomial relationship was proposed to accurately represent the Bakken Shale maturity. Tmax, liptinite fluorescence, SBRO, and NMR as thermal maturity indicators were utilized to establish a reliable database to compare redox-sensitive trace metals (TM) concentration to maturity variations.

Comparing TMs concentration with TOC confirmed the presence of anoxic/euxinic conditions in the depositional environment. A relative enrichment in TMs was detected with all utilized indices, confirming that thermal maturity has played an important role in TMs concentrations.

OM particles were found that are evolving in-situ into solid bitumen. This in-situ bituminization allows examination of a continuous transformation in OM molecular structure at micron-scale using AFM-IR spectroscopy applied at the transition zones. The OM chemical heterogeneity was examined at the nanoscale. Significant heterogeneity was observed within unaltered telalginite and bacterial degraded Tasmanites, and also between two separate solid bitumens that are next to one another and at the same stage of thermal progression. While thermal maturity progression was found to reduce molecular heterogeneity in the organic matter particles during the maturation pathway, on the contrary, during the bacterial degradation, the Tasmanites has lost its fluorescence and the relative heterogeneity was increased compared to the unaltered telalginite.

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