Characterization and Simulation of a Complex Sub Salt Fractured Carbonate Field Offshore Brazil

The considered oilfield was recently discovered as part of Petrobras effort in developing subsalt assets. As with many carbonate fractured reservoirs it has proved difficult to describe and model the fracture distribution and their consequence on the reservoir effective permeability especially in its current exploration and delineation phase where the wells are limited to three or four at most. This integrated study used geophysical, geologic, and engineering data simultaneously to improve the reservoir description. The characterization of the fractures was mostly due to the extensive use of narrow azimuth 3D post and pre-stack seismic data. The derived 3D seismic attributes and 3D geologic and fracture models were used to better understand the factors affecting the distribution of the key rock properties including the fractures and their effect on the permeability. The resulting porosity, water saturation and permeability models were input into a reservoir simulator and allowed the reasonable match of the individual well performances without the need for any extensive history matching thus validating the input reservoir models. This achievement was made possible by the use of key high resolution post and pre-stack seismic attributes as drivers in the CFM technology that provided the resulting rock properties.