A reservoir characterization for a complex multilayered system in Eastern Venezuela

Abstract

To predict and optimize reservoir performance of a raphics. layered reservoir, a reliable reservoir characterization is required. To fully describe a reservoir, we must be able to estimate the distribution of reservoir properties such as porosity and permeability by integration of all available data. In this research, we have characterized a multilayered reservoir located in eastern Venezuela. A methodology was developed to estimate the distribution of reservoir properties in uncured intervals and welts using data from core and log analyses. In addition, to obtain a better understanding of formation permeability, skin factors and drainage areas, we have analyzed all of the production data. The data used in this study, were provided by PDVSA the Venezuelan national oil company and comprises: production data, well ales, core analyses, well log data, some PVT analyses, and well completion data. Four formations were characterized in this work. Correlations from core data were established to calculate permeability for each of those four formations. To identify the four reservoirs in uncured welts, a characteristic behavior of the values of deep induction log and gamma ray log were determined. This behavior permitted us to establish ranges for each zone using data from both logs. The oil in place for each formation was calculated volumetrically. Using the values obtained for permeability, porosity, shale volume and oil in place, the four reservoirs were volume and oil in place, the four reservoirs were The results obtained from the analyses of production data, were compared with the analyses of log and core data. Using all three methods, the shallower zones were identified as the more permeable layers. The deeper formation (Cretaceous) has a lower permeability value, but the OOH: is high enough to justify completing the Cretaceous, especially if the zone can be fracture treated.