Characterizing the Pore Structure of the Marcellus Shale

摘要

The large hydrocarbon resource and recent success of exploration and exploitation in mudstone (shale) reservoirs has stimulated research interests in these unconventional oil and gas reservoirs. Mudstone is categorized as an unconventional reservoir because of the nanometerscale pore sizes and extremely low nano-darcy permeability compared to micrometer to millimeter-scale pore sizes and millidarcy to darcy permeability of conventional sandstone or carbonate reservoirs. The introduction of advanced imaging technology provides a powerful tool to examine the complex pore structure of mudrock, although quantification remains a challenge. In addition to the free void space of pores, there is an extra storage mechanism for shale gas, adsorbed gas on pore surfaces of organic matter and clay particles.;Porosity, as a critical reservoir property, has been used to calculate reserves, and permeability to estimate production rates. For an unconventional reservoir, the quantification of porosity and permeability is challenging because of the complexity of pore structure, and the extremely small size of the pore space. In this research, I introduce two cutting-edge technologies, semi-automatic analysis of ion milled scanning electron microscopy (SEM) images, and subcritical N2 adsorption. The new technologies can be used to quantify and compare the results with other more conventional methods in order to improve our understanding of the pore structure of mudrock at a range of spatial scales. I integrate multiple techniques to characterize the pore system structures of the Marcellus Shale reservoir and improve our understanding of the evolution of organic-matter pores through lithology, richness of organic matter, and thermal maturity.