Synthetic capillary pressure modeling with dipole sonic waves for enhanced reservoir characterization

This study presents a mathematical framework for generating synthetic capillary pressure curves using dipole sonic log information and a fractal model of the pore structure. The approach estimates key petrophysical properties such as porosity and elastic constants by simulating the deformation behavior of porous media under effective stress conditions through boundary element methods. Pore geometries are modeled using a combination of Euclidean shapes and fractal distributions, which allow for realistic simulation of elastic responses and pore volume variability. A central issue addressed is the non-uniqueness problem, where different pore structures can produce similar elastic properties. To mitigate this, the model incorporates a fractal pore population constrained by scaling laws derived from empirical studies. This enables a more consistent and physically meaningful interpretation of sonic log responses. The methodology was validated using field information from the Tapi–TTT Oilfield in the Oriente Basin of Ecuador and further evaluated in the Las Piedras Formation in western Venezuela. In both settings, the synthetic capillary curves showed strong agreement with laboratory measurements. This framework offers a scalable and replicable alternative to core-based methods, providing a robust tool for characterizing reservoirs in formations where core data are unavailable or laboratory techniques are impractical.