Digital core analysis: Characterizing reservoir quality through thin sandstone layers in heterolithic rocks

Abstract

Conventional reservoir models of heterolithic reservoirs do not include millimetre-to-centimetre sandstone layers due to the resolution limitations of widely used well logs and core plug data, resulting in underestimation of hydrocarbon reserves. Continuity and the reservoir quality of the thin sandstone layers in heterolithic reservoir are critical factors for hydrocarbon reserves. We use multi-scale Digital Core Analysis techniques to estimate the reservoir properties (porosity and permeability) and characterize the connectivity of millimetre-to-centimetre sandstone layers in heterolithic rocks. We show that a reservoir heterolithic core plug contained continuous sandstone layers with permeability and porosity that are similar to a reference reservoir sandstone. A non-reservoir heterolithic core plug has thin sandstone with discontinuous layers with permeability and porosity that are significantly lower compared to the reference reservoir sandstone. We show that Digital Core Analysis can characterize reservoir properties at the millimetre-to-centimetre scale that contributes to a multi-scale reservoir model for improved hydrocarbon reserves estimates in heterolithic reservoirs.