Predictive Modeling of Reservoir Quality Associated with the Dissolution of K-Feldspar During Diagenesis: Lower Cretaceous, Scotian Basin, Canada

The distribution and quality of the Lower Cretaceous reservoir sandstone units of the Mesozoic–Cenozoic Scotian Basin, offshore eastern Canada, is well known in producing fields but difficult to extrapolate to less-explored areas of the deep-basin floor. Prediction of reservoir risk is complicated by salt tectonism and the strong influence of diagenesis on reservoir quality. This study investigates the burial diagenetic dissolution of detrital K-feldspar in the subarkosic sandstones and the preservation of the resulting secondary porosity. K-feldspar abundance declines with increasing depth, creating secondary porosity, which in open systems is preserved but in closed systems is clogged by carbonates and clays. The distribution of detrital K-feldspar has been simulated using forward stratigraphic modeling and is compared to thermal modeling, fault mapping, and sand distribution to determine the risk due to the reservoir quality, illustrated as common risk segment maps. Sand deposits have the lowest risk of poor reservoir quality along the shelf edge and upper slope of the central and western basin, where growth faulting created an open diagenetic system. This novel combination of petrographic study and forward modeling has applications to other regions where diagenesis has a strong influence on the reservoir quality, such as the Gulf of Mexico.