A pressure-dependent rock physics modelling procedure for source rocks of Palermo Aike Formation

Abstract

We present a semi-empirical approach to obtain an anisotropic stress dependent rock-physics model for samples of the Palermo Aike formation, Argentina. The workflow combines a well known phenomenological velocity-pressure law with concepts of poroelasticity theory. Dataset consists on three-plugs with angles 0, 90 and 45 respect to bedding plane on which ultrasonic velocities were measured to study anisotropic effects. Our model is calibrated using density data, X-Ray Diffractometry information for lithologic description, Total Organic Carbon analysis for organic content, He-Porosimeter for effective porosity and Nuclear Magnetic Resonance (NMR) for fluid content, type and total porosity. In this way we obtain pressure dependent anisotropic elastic moduli. This allows us to fit compressional and shear wave velocities, predict porosity variations with confining pressure and estimate physical properties of kerogen in the samples. Upscaling this model to well could help to predict poroelastic effects that are critical during well completion design.