An integrated approach to define new plays in mature oil basins: the example from the Middle Magdalena Valley basin (Colombia)

Abstract

An integrated approach to detect new areas of potential interest associated with stratigraphic traps in mature basins is presented. The study was carried out in the Middle Magdalena Valley basin, Colombia. The workflow integrates outcrop and subsurface interpretationsoffacies,activityoffaults,anddistributionofdepocenters and paleocurrents and makes use of them to construct a threedimensionalexploration-scalegeocellularfaciesmodelofthebasin. The outcrop and well log sedimentological analysis distinguished faciesassociationsofalluvialfan,overbank, floodplain,andchannel fill,thelastoneconstitutingthereservoirrock.Theseismicanalysis showedthattectonicactivitywas coevalwiththedepositionofthe productive units in the basin and that the activity ended earlier (before the middle Miocene) along the western margin than along the eastern margin. Paleogeographic reconstructions depict transverse and longitudinal fluvial systems, alluvial fans adjacent to the activebasinmargins,and floodplainfaciesdominatingthestructural highs and the southwestern depositional limit. These reconstructions provided statistical data (lateral variograms) to construct the model. The exploration-scale facies model depicts the complete structureofthebasininthreedimensionsandthegrossdistribution of the reservoir and seal rocks. The predictive capability of the model was evaluated positively, and the model was employed to detect zones of high channel fill facies probability that form bodies that are isolated or that terminate upward in pinchouts or are truncated bya fault. Our approach canprovehelpfulinimproving general exploration workflows in similar settings.