A Workflow for Multimineralogic Carbonate Rock Physics Modeling in a Bayesian Framework
Carbonate reservoirs in the Brazilian Pre Salt have reached notoriety in recent years due to their high productivity and economic benefits. These facts motivated efforts to better understand the main factors driving carbonate elastic attributes and their relationships with pore types and petrophysical properties. These rocks intrinsic features bring challenges to understanding seismic signatures, to the application of AVO analysis and the derivation of direct hydrocarbon indicators. The key to unlocking reliable 3D and 4D quantitative seismic interpretations, forward seismic modeling and feasibility studies is a well parametrized and calibrated rock physics model. Therefore, we develop a workflow using a carbonate rock physics model to estimate elastic attributes of a Pre Salt carbonate reservoir for one calibration and three extrapolation wells through a Bayesian Framework to handle its parameters non uniqueness. We take into account that the matrix properties (density, bulk and shear moduli) vary with depth and demonstrate an improvement in Vp and Vs estimations within the reservoir, compared to the common practice of allowing only porosity to vary with depth and representing the matrix properties by a depth invariant homogeneous or mixed mineral.