EXPERIMENTAL INVESTIGATION OF MATURATION PROCESSES AND ITS RESULTANT IMPACT ON ORGANIC MATTER

Organic material within source rocks consists of extremely complex macromolecules made largely of hydrogen and carbon structures together with a host of other minor components. The process of oil generation involves breaking bonds within these macromolecules to form mobile and soluble hydrocarbon fragments that together mix to form mobile crude oil and natural gas or immobile bitumen. Even though the processes and mechanisms of oil generation are exceedingly complex, there is general concession that overall reaction rates correlate with the Arrhenius Equation. The objective of this study is to experimentally determine the changes that occur in organic matter during maturation, by analyzing changes in the organic geochemical properties of the Bakken Shale during maturation and also evaluating the hypothesis that there is a secondary compensation effect between E_a and ln(A) (kinetic parameters).

In this study, we utilized artificially matured Bakken Shale samples kept in the oven at 340°C with increasing thermal maturity (T_max 419-445°C). Firstly, we conducted source rock analysis to evaluate the geochemical properties. Secondly, the samples were analyzed to obtain the kinetic properties. We then conducted scanning electron microscopy to describe the modification in the texture and distribution of organic matter. Lastly, we used a reflected light microscope for the characterization of visible kerogen.

Our results show that the geochemical properties, such as the total organic carbon content (TOC) and hydrogen index reduced with increasing thermal maturity. It also shows that there exists a secondary compensation effect when Bakken shale samples are repeatedly analyzed. Further analysis of our results provides the basis for calibrating kinetic parameters (E_a and A) and other organic chemistries and indices, to specific degrees of thermal stress. While this study focused on the Bakken Shale Formation in the Williston Basin, we expect that the methodologies and results provided in this study will be resourceful when applied to other sedimentary basins.