Organic matter exerts a fundamental control on porosity and permeability in organic-rich tight hydrocarbon reservoirs. The complexities of these relationships are not well defined however and may be influenced by a variety of factors including organic matter richness, thermal maturity, kerogen type, original kerogen structure and primary organic-hosted porosity, compositional fractionation, interaction with mineral catalysts, compaction, and occlusion by generated products such as solid bitumen.
This abstract presents preliminary results from the first of three wells analyzed in the play fairway of the Duvernay Formation of western Canada -a prolific source rock and rising star as an unconventional reservoir. Distinct porosity morphology groups have been observed in SEM and ongoing work has shown that organic matter porosity morphology may be influenced by organic matter composition and degree of isolation from nearby macerals. Integration of porosity calculated from image analysis of focused ion beam scanning electron microscopy (FIB-SEM) images with results from nuclear magnetic resonance (NMR), mercury injection capillary pressure (MICP), and helium porosimetry has demonstrated that a significant portion of the porosity is below typical SEM imaging resolution and that even methods such as He-porosimetry are challenged to access nanometer-scale pores. Variations in sample preparation and analysis procedures can significantly alter porosity results.