Characterization of elastic moduli with anisotropic rock physics templates considering mineralogy, fluid, porosity, and pore-structure: A case study in Volve field, North Sea

Abstract

A practical methodology was designed to characterize mineralogy and the rock microstructure by constructing anisotropic rock physics templates (ARPTs) based on the Effective Medium Method (EMM). The ARPTs consider parameters such as pore aspect ratio (α), porosity, fluid saturation, and elastic properties of rock minerals. A three-stage methodology was applied to an oil well for a sandstone formation in the Volve field, North Sea. The first stage is the petrophysical evaluation, which is validated with core data. The second, the inversion scheme with differential effective medium (DEM) was used to predict aspect ratios in depth. The obtained results characterize the sandy formation setting intergranular porosity with 0.12 < α < 0.3, although there is also the presence of stylolites caused by the dissolution mechanism between quartz, feldspar, mica, calcite, and clay. The validation of the pore-structure is accomplished with thin sections. The last stage comprises the construction of ARPTs, which includes the axial and two transversal templates of Young's modulus versus Poisson's ratio. These templates are used to characterize lithology, porosity, pore-structure, and the mechanical behavior of the sandstone formation from well logs and gave invaluable information about the pay zone. In addition, because the lithotype interpretation proposed is merely borne by rock's elastic properties, it has the potential to be scaled to field scale by using seismic inversion data.