A geochemical characterization of well cuttings from an oil producing well in the Central Kansas Uplift using metal analysis and magnetic susceptibilities
Samples of well cuttings from a well drilled in the Central Kansas Uplift were obtained every 10ft between 3150ft-3875ft. Geochemical and magnetic susceptibility (MS) studies were conducted on these cuttings. Prior to analysis, samples were observed using optical microscopy and well logs were analyzed to describe the lithology. All samples for the analyses were crushed and dried. For elemental analysis, further digestion was done using HCl and HNO3. Major and trace metals analysis was done using Flame Atomic Absorption Spectroscopy. The objectives of this study was to: (1) conduct a high resolution lithofacies characterization using the metal compositions for known lithologies, (2) compare Fe concentrations with MS measurements throughout the interval to assess zones of possible oil degradation and (3) conduct a chemostratigraphic characterization and correlation with data from surrounding wells. Results show that the dominant lithofacies for the studied interval consist of limestones with some silts, interbedded shales, and dolomitic layers. High Ca and Mg concentrations support limestone and dolomitic facies in the samples. Observations show that intervals above oil bearing units contain higher amounts of pyritic minerals and high Fe concentration. These elevated Fe concentrations correlate with elevated Pb concentrations in samples. High Fe concentrations correlating with petroleum zones indicate possible microbial mediated hydrocarbon degradation.
AAPG Datapages/Search and Discovery Article #90221 © 2015 Mid-Continent Section, Tulsa, Oklahoma, October 4-6, 2015