Although most agree that micropores are important for scientific and economic reasons, geologists and material scientists have diverse opinions on the very definition of microporosity and its possible origin(s). To explore the nature and genesis of micropores, Hasiuk and others examine bulk stable-isotope and elemental analyses from a range of microporous limestone hydrocarbon reservoirs and a compilation of geochemical data from previous studies of subsurface microporous limestones from the Phanerozoic. Results illustrate microcrystals are composed of low-Mg calcite, and geochemical data suggest most are abiotic origin, but modified by shallow-burial diagenesis. On this basis, the authors suggest a uniform, diagenetic origin during early burial for the micrite that hosts most microporosity in limestone oil reservoirs. This understanding is a first step in modeling the distribution of microporosity in reservoirs, enhancing accurate prediction of reservoir performance.
Diagenetic origins of the calcite microcrystals that host microporosity in limestone reservoirs by Franek J. Hasiuk, Stephen E. Kaczmarek, and Shawn M. Fullmer