Contributions of digital image analysis to sedimentary rock characterization

Abstract

This article presents results achieved by a series of studies aiming to evaluate petrophysical properties from digital images of sedimentary rocks. This characterization from digital images occur in the pores and grain scale, but it is confronted with the same properties as they are conventionally measured on the centimeter scale of laboratory rock samples. The properties evaluated were the porosity of macro and micro pores, mineral composition, the size distribution of grains and pores, sphericity and roundness of the mineral grains, permeability, the quality of grain-grain contacts, elastic wave velocities and electrical properties of the rocks. Predictive models for permeability and elastic velocities of carbonate rocks are presented for the estimation of these properties from the extracted parameters of rocks’ digital images. Beyond of elastic properties (e.g. VP and VS), important parameters for estimation of hydrocarbon reserves, such as tortuosity factor and saturation and cementation coefficients, are evaluated through the digital models of rock.