Workflow for Geological Characterization and Modeling of the Albian Carbonate Reservoirs from Offshore Campos Basin, Brazil
Recent and very important oil discoveries in Albian carbonate reservoirs from the shallow to deep waters of the eastern Brazilian marginal basins have led Petrobras to promote large efforts to develop workflows for the geological characterization and modeling of these complex reservoirs. The Albian carbonate reservoirs make part of elongated shoals, which are composed mostly of grainstones and packstones containing mostly oncolites, peloids, and oolites. The oil accumulations have a strong structural control, provided by faulting and folding.
This paper is focused on the general workflow developed for the geological characterization and modeling of the Albian carbonate reservoirs, and the application of this workflow in one of these important oilfields. This workflow is being used in a long term training program through an agreement between PETROBRAS and UNESP (São Paulo State University). During the development of this project, the students have to develop a 3D geological model for a carbonate reservoir, which will be used in fluid flow simulation, by using the following workflow: (1) description of cores and thin sections; (2) petrophysics and rock-well log correlation; (3) high-resolution stratigraphic analysis; (4) seismic interpretation of main stratigraphic surfaces, faults, and generation of a seismic acoustic impedance volume; (5) construction of a conceptual geological model for the field by using outcrop and subsurface analogs and all the available data; (6) definition of the 3D structural-stratigraphic framework to support the building of a 3D geocellular model to be populated with facies and petrophysical variables, considering seismic horizons, fault planes and well log markers; (7) generation of a 3D geocellular model with depositional and diagenetic facies using monogaussion and plurigaussian non-stationary geoestatistical modeling conditioned by facies proportion maps; (8) generation of a 3D model for the reservoir porosity, permeability and oil saturation conditioned by interpreted logs (phase 2), capillary pressure curves and acoustic impedance (phase 4); (9) validation of the model after each individual phase using quantitative and qualitative criteria; and (10) volumetrics and exportation of the static model to a fluid flow simulator; STOOIP calculation, upscaling and exportation of the geocellular model to a fluid flow simulator.
AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.