Pore Type and Aspect Ratio Prediction - A Known Parameter for Seismic Monitoring Strategies - and the Pre-Salt Reservoir Carbonatic Rocks Application

Abstract

Microbialites and coquinas compose the large pre-salt carbonate reservoirs for hydrocarbon accumulations of the Santos Basin, Brazilian offshore. The complexity of this type of rock poses major challenges for the reservoir characterization, especially the microbialites ones. This article presents a well log study relating the deviations of P-wave velocities with the aspect ratio observed in these specific rocks. In our suggested approach, we analyze the facies logs to obtain a relation between these deviation effects and the pore type. The facies analysis allows us to better separate the microbialite and coquina rocks, covering significant differences in porosity and diagenetic processes. We state for the analyzed rocks that the vug features are the predominant pore type for both lithologies, and that this aspect reflects the results of velocity deviations and aspect ratio values. This information is applied to build petro-elastic modeling to assist in seismic monitoring of the reservoir.