Work

An extended differential effective medium theory: linking pore geometry and elastic moduli in carbonate rocks

Year: 2026

Type: article

Abstract: SUMMARY The differential effective medium (DEM) theory is widely used to estimate the elastic properties of reservoir rocks based on their constituent minerals and pore fluids. However, its dependence on ideal ellipsoidal pores limits its applicability to rocks with irregular and complex pore geometries, particularly carbonate rocks. In this study, we present an extension to the DEM framework that incorporates a perturbation tensor to account for deviations from ideal ellipsoidal inclusions. For isotropic composites, this tensor reduces to two scalar coefficients that quantify the mechanical impact of pore-shape irregularities. The physical significance of these coefficients is investigated through numerical simulations on synthetic rocks with controlled pore geometries, where pore-shape complexity is quantified using a convexity-based metric. The simulations show that the perturbation coefficients systematically increase with decreasing convexity within a given shape family, indicating enhanced compliance associated with more irregular pore shapes. The extended DEM model is further validated using well-log and microcomputed tomography data from carbonate reservoirs in the Mumbai Offshore Basin, India. The inclusion of perturbation coefficients substantially improves the prediction of shear-wave velocity compared to the standard DEM approach. Overall, the extended DEM framework provides a practical means of incorporating the mechanical effects of irregular pore geometries into rock-physics models, thereby improving the characterization of elastic properties in heterogeneous carbonate systems.

Source: Geophysical Journal International

DOI: 10.1093/gji/ggag222

Authors: Sanjay Arjun Pandit, Kumar Hemant Singh

Institution: Indian Institute of Technology Bombay

Language: English

Topic: Seismic Imaging and Inversion Techniques

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,416

Funders: Indian Institute of Technology Bombay, College of Education, Arkansas Tech University