The University of North Dakota Petroleum Engineering team have new findings in the changes in the pore structure distribution after CO2 saturation. Ogochukwu Ozotta, a PHD candidate, will provide an in-depth look at the changes in the Bakken formation, the first step in providing experimental evidence to further test the mechanisms of geological storage of CO2 in organic-rich self-sourced.
The interaction between various components of shale and CO2 is interesting since it alters pore structures that are the governing factor in different projects. In this study, samples from the Upper (UB) and Lower (LB) Bakken were exposed to super critical CO2 for 3, 8, 16, 30, and 60 days. Then, chemical and structural changes during the process of exposure were evaluated with different methods, including X-ray diffraction (XRD), gas adsorption (N2) isotherm, and fractal theory. The results showed that quartz increased in the UB and decreased in the LB, whereas clay and other minerals had a decreasing trend for both UB and LB after CO2 saturation. After saturation, the pore size distributions (PSDs) were skewed to smaller pore sizes at all diameters, indicating that the number of pores decreased as a result of the reaction. Fractal dimension has an increasing trend as the samples were exposed to CO2, where the roughness of the pore surface and the complexity of pore structure increased after 8–16 days of CO2 saturation and then decreased after 30–60 days of saturation to become more homogeneous.