Kerogen Porosity in Marcellus Shale Across a Maturation Gradient
Geoscience, Pennsylvania State University, State College, PA, USA
Recently, the production of natural gas from black shale has increased dramatically. It has been demonstrated that most of the storage capacity and effective network in black shales may in fact be controlled by nanopores in kerogen rather than the mineral matrix. Several studies suggest that pores in kerogen are generated during hydrocarbon maturation. However, the relationship between kerogen porosity and maturation is still unclear, in part because no single technique can satisfactorily measure the wide range of distribution of pore size. In this study, I plan to use electron microscopy to visualize the kerogen pores and ultra small- and small-angle neutron scattering to characterize the pore structure over a wide range of length scales from nanometers to micrometers.
More importantly, I have also successfully developed a new technique to quantify nanopores in kerogen. In this technique I use ultra small- and small-angle neutron scattering on dry samples and wet samples (using a contrast matching method) to distinguish pores in mineral matrix and pores in kerogen. This method has been applied for Marcellus shale samples from a postmature core with a vitrinite reflectance, R0, >2. We found that the pores occupy around 25% of the kerogen volume, which is close to the values derived from a theoretical model in the literature. For a better understanding of the evolution of kerogen porosity with maturation, less mature samples of Marcellus shale – spanning a range from the early oil to the dry gas window (0.3< R0 <2) – will be investigated in this study.
AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects