Publication Date

Fall 2016

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

Advisor

June A. Oberdorfer

Keywords

Clay, Diagenesis, Geochemistry, Hydrothermal experiments, Illite, Petrology

Subject Areas

Geochemistry; Geology; Petroleum geology

Abstract

Two hydrothermal experiments were performed using sandstone core material from

the Norwegian North Sea with synthetic brines reacted at approximately 150˚C and 450

bars, temperature and pressure calculated to simulate a depth of burial of approximately 4 km. The results of the experiments were analyzed with geochemical modeling and with

chemical and petrographic analyses. Geochemical modeling with several computer

programs indicated that the experimental fluid was undersaturated with respect to K-feldspar, kaolinite, and illite, but supersaturated with respect to muscovite. Chemical

analysis with inductively-coupled plasma mass spectrometry indicated that the fluid

reached saturation with respect to K-feldspar. Petrographic analysis with scanning

electron microscopy and energy-dispersive scanning indicated that changes took place

over the course of the experiments in both the clay and non-clay mineral fractions, and

this result was verified by X-ray diffraction analysis that indicated dissolution of both K-feldspar and illite and formation of muscovite. These converging lines of evidence

indicate that significant changes took place in the clay mineral fraction of the

experimental sandstone core material, reacted at realistic basin temperature, pressure and geochemical conditions, over the course of several weeks.

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