CHACARTEGUI, FERNANDO, MARIA C. COLL, JORGE URDANETA, JOHNNY PINTO, and DIOGENES LUGO, Maraven, S.A., Caracas, Venezuela
ABSTRACT: Laminated Sandstones Reservoir Characterization, Middle Eocene Lower Misoa Formation, Ceuta Field, Maracaibo Lake
This study presents the results of a multidisciplinary, project and methodology used to describe a clastic reservoir, known as C-2/C-3, characterized by thin sandstones units masked by a mainly argillaceous sequence. The area, known as Area2 of the Ceuta field, is located to the southeast of the Maracaibo Lake, comprising an area of 75 sq km. Sedimentological facies description, characterization and analysis resulted in the identification of seven different lithofacies, of which only two are productive. Additionally, ten sedimentary units were recognized, based on related facies associations and nature of facies contacts. These sedimentary units were deposited by a prograding, fluvially-dominated delta in a large estuarine environmental setting. Integration of sedimentological and pet ophysical data were used to recognize and predict prospective intervals from well logs and to characterize them. A deconvolution of MICRO LOG resistivities proved to be the most successful technique to delineate productive intervals, and set the basis for flow unit identification. Production data, integrated with petrophysical and sedimentological parameters, were used to identify and characterize six flow units from the entire sequence. Log correlations, based on the sedimentological framework and stratigraphic
sequence analysis techniques, in addition to 3-D seismic interpretations, were used to stablish the external geometry and extension of flow units and thus, delineating the areal and vertical limits of the reservoir. Reservoir application of this project include successful placing of appraisal wells to the south, grass-root drilling to the north, optimization of workover wells over the entire area and a more realistic reserves quantification.
AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.