Geological modelling applied to reservoir simulation, an example from Pargo Field, Campos Basin

Abstract

It is well known that oil reservoirs, with strong water drive show high recovery efficiency, but when  production water-oil ratio increases rapidly, the ultimate oil recovery decreases. The main purpose of this research is to define a geological model for this type of oil reservoir, in an appropriate scale and including heterogeneities, which should explain the reservoir performance of Pargo Field, Campos Basin. Such a model should honor the observed  high water-oil ratio, so that the f1uid tiov« simulation would be able to indicate the preferential pathways through which water f10ws to the drilled intervals. Some extensive impermeable shale beds, which are the major features of the model, are effective vertical barriers for f1uid f1ow. A fence diagram is an adequate iIIustration of the physical model. The ttow simulation was performed adjusting the vertical boundaries of the layers with these shale beds. Permeability and porosity were allowed to change from cell to cell. A new method was developed to estimate and correIate permeability with porosity in the Pargo Field. After the water cut history has been fitted, several altematives of extrapolation for production were done. The resu/ts of the basic case were compared to new proposed locations and different options of completed intervals, with the purpose of improving oil recovery in this problematic reservoir. The best altemative provided an increase of about one mil/ion of cubic meters of oi/, until the end of the year 2.000.