Calibration of a poroelastic rock physics model from well logs and cuttings: a case study from Inoceramus shale, Austral basin, Argentina

Abstract

The evaluation of elastic and geomechanic coefficients in reservoir rocks at well scale is needed for their characterization and also for planning drilling and production strategies. This is very important in unconventional organic rich shale reservoirs such as Inoceramus formation, the main source rock in Austral Basin, Argentina. In previous studies we described and quantified the elastic anisotropy of Inoceramus shales (Panizza et al. 2022), using core plugs and ultrasonic velocities. Well logs do not provide enough information to determine the whole stiffness (or compliance) tensors. We show that rock physics tools are highly useful for this problems. We propose a workflow for the calibration of a poroelastic velocity model at in situ differential stress conditions, using well logs and laboratory measurements on cuttings. Our model is based on a combination of the theory porosity-deformation approach (Shapiro & Kaselow 2005, Shapiro, 2017) and Ciz & Shapiro (2007). The calibration procedure involves the utilization of an inversion method to determine model fitting coefficients and physical properties of the organic matter (kerogen).