Date of Award
Doctor of Philosophy (PhD)
Chemistry and Biochemistry
Patrick G. Hatcher
James W. Lee
Ancient organic matter (OM) in shales and coals, known mainly as Type II and Type III OM are known to produce both biogenic, thermogenic gas and oil. In this dissertation, mild artificial maturation, via closed system pyrolysis, is employed to determine the thermal reactivity of Type II and Type III OM beyond diagenesis. We select three Type II kerogens: i) Type II kerogen isolated from recent cores (3.3 Ma, Ro = 0.28) recovered from an upwelling basin in Namibia, Africa referred to as ODP Sediment, ii) Type II-S isolated from sediments (150 Ma, Ro = 0.38) recovered from an outcrop near the Volga River, Russia referred to as Bazhenov Source Rock (S.R.), iii) Type II kerogen isolated from sediments (185 Ma, Ro = 0.62) recovered from an outcrop in the Paris Basin, France referred to as Toarcian S.R.. Furthermore, we select four Type III kerogens in which three from deep coalbed layers in Shimokita, Japan and the fourth from the Calvert Bluff Formation, Texas, USA. Our results show that the structural identity is significantly altered because a major portion of oxygenated compounds such as Alkyl – O, esters and carboxylic acids is lost based on solid state 13C Nuclear Magnetic Resonance of the solid residues. Gaseous and liquid recoveries quantitatively show that CO2 and asphaltenes are the primary thermal products. For Type II kerogens, CO2 was co-generated with asphaltenes while for Type III kerogengenerated less thermal products with CO2 slightly later than asphaltenes. For Type III kerogens, the three coalbeds seem to generate thermal products with respect to their maturity levels. Using optimized activation energies set between 30 and 48 kcal/mole, bulk kinetics studies reveal that the onset of thermal generation of CO2 and asphaltenes from Type II and Type III kerogens initiates at 10 degree C with maximum product yields reached below 70 degree C. The molecular characterization of asphaltenes reveals the dominance of long chain fatty acids and diacids with similar bulk kinetic parameters as the global degradation of kerogens. These long chain fatty acids and diacids possess the highest conversion rate into biogenic methane.
Nguena Kamga, Albert W..
"Low-Temperature Artificial Maturation Studies of Type II and Type III Kerogens: Implications for Biogenic Gas Production"
(2016). Doctor of Philosophy (PhD), Dissertation, Chemistry and Biochemistry, Old Dominion University, DOI: 10.25777/5sj5-4y45