Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Geology

Supervisor

Burns Cheadle

Abstract

Pores that develop within kerogen particles make a significant contribution to the network flow capacity and hydrocarbon storage of carbonaceous mudstone reservoirs. It has been suggested that development of Organic matter pores results from thermal degradation of kerogen. The range of thermal and subsidence histories of strata in the Western Canada Foreland Basin provide an excellent framework in which to evaluate the influence of thermal maturity on organic matter micropore morphometrics, and the opportunity to evaluate clay microfabric characteristics. Imaging and pore characterization of mudstone samples from the Upper Cretaceous (Cenomanian-Turonian) Colorado Group of the WCFB has been conducted using the focused ion beam/ scanning electron microscope system in the Western Nanofabrication Facility. Interparticle pores between grains and interparticle and intraparticle pores between /within clays contribute most of the porosity. Clay fabrics with abundant edge-to-edge and edge-to-face contacts are mostly observed in the forebulge and backbulge segments of the basin due to preservation from compactional reorientation. Intraclastic aggregates and organomineralic aggregates are recognizable across the basin. The shapes and spatial distribution of OM pores are highly heterogeneous, which is probably controlled by maceral type, possibly modified by surface interface chemical reactions with clay minerals. There is no correlation between the abundance of organic matter pores and thermal maturity. Organic matter pores in immature samples were probably produced during microbial degradation at relatively low temperatures. Additionally, widespread occurrence of intraclastic aggregates suggests prevalent conditions of seabed erosion and a relatively energetic depositional setting of the mudstones.

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