Year of Publication

2013

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Arts and Sciences

Department

Geology

First Advisor

Dr. Thomas M. Parris

Second Advisor

Dr. Alan E. Fryar

Abstract

This study examined CO2-water-rock interactions occurring during a carbon sequestration pilot test into a Mississippian oil reservoir in western Kentucky. New samples (n=62) and archived data, both collected from oil wells, were used to characterize the chemistry of formation waters from the Sugar Creek field in Hopkins County. In addition, core and cuttings samples (n=17) from the reservoir and overlying cap-rocks in, or near, the field were analyzed for bulk and clay mineralogy using X-ray diffraction. Electric logs were used to select sample intervals within the overlying cap-rocks and the center of the producing zones in the Jackson Sandstone. Using the water chemistry and mineralogic data as inputs, speciation and reaction path models were created using the Geochemist’s Workbench software (GWB) to predict the distribution of aqueous species at equilibrium, evolution of fluid chemistry, and reservoir mineralogy as CO2 was injected into the reservoir. Formation water was primarily Na-Cl. Reservoir rock was predominantly quartz. GWB simulations at the injection wells, mid-point fugacity and production wells indicated a sharp decrease in pH and increase in CO2 (aq). Delta mineral mass plots showed net dissolution for injection stages and net precipitation for post-CO2 injection. Important minerals were carbonates and alumino-silicates.

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