173-12 Geochemical and Biomarker Characterization of Kansas Hydrocarbons: Implications for Source Rock Attribution

Session: Geologic Energy Resources and Storage for Now and the Future

Presenting Author:

Oluwaseun Omoyemi

Authors:

Omoyemi, Oluwaseun Victoria¹, Ajulo, Olumide Olawale², Towoju, Victor Olushola³, Ademilola, Joshua Adeyemi⁴, Titah, James⁵, Hanson, Samuel⁶, Agbogun, Henry M. D.⁷

(1) Department of Geosciences, Fort Hays State University, Hays, KS, USA, (2) Department of Geosciences, Fort Hays State University, Hays, KS, USA, (3) Department of Geology and Geophysics, Texas A&M University, College Station, TX, USA, (4) Boone Pickens School of Geology, Oklahoma State University, Stillwater, OK, USA, (5) Department of Chemistry, Tabor College, Hillsboro, KS, USA, (6) School of Arts, Science and Education, Medicine Hat College, Medicine Hat, AB, Canada, (7) Department of Geosciences, Fort Hays State University, Hays, KS, USA,

Abstract:

Hydrocarbon production plays a significant role in the Kansas energy sector, yet the geochemical characteristics and sources of these hydrocarbons have not been extensively studied. While key petroleum system elements like the reservoir rocks, seals, and traps are well defined within the state, the source rock(s) remain a subject of debate. This study presents a comprehensive geochemical characterization of eighteen hydrocarbon samples collected from five subbasins and six producing intervals across Kansas, utilizing gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques.

Biomarker and non-biomarker parameters such as Pr/Ph ratios ≥ 1, low NP/AK, CPI ≥ 1, and C29/C30 hopane ratios < 1 indicate a predominantly shale-derived source rock across all sampled regions. Sterane and terpane biomarker distributions further differentiate the organic matter source, with hydrocarbons from the Central Kansas Uplift (CKU), Hugoton Embayment (HUE), Salina Basin (SLB), and Sedgwick Basin (SGB) suggesting marine origins, whereas oils from the Forest City Basin (FCB) are terrigenous. Pr/n-C17 vs. Ph/n-C18 crossplot and Pr/Ph ratios (0.98-2.25) support hydrocarbon generation in marginal marine settings under suboxic redox conditions without water stratification, as evidenced by C35 homohopane index, C32/C31 hopane ratios, and Gam/C30 hopane crossplot. Thermal maturity assessments, including CPI and OEP values of 1.0, steranes and terpane isomerization ratios such as C29 sterane 20S/(20S + 20R), C29 sterane ββ/(ββ + αα), C32 homohopane 22S/(22S + 22R) ratios (0.59–0.64), moretane/hopane values (0.09–0.16), and Ts/(Ts + Tm) plot confirm that the source rocks lie within the oil generation window. These results collectively offer insights into the source origin, depositional environment, redox conditions, and the maturity of the organic matter that generated hydrocarbons being produced across different subbasins in Kansas.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10837

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