Contrasting Two Methods Along the Spectrum of Geologic Concept vs Seismic-Driven Approaches to Reservoir Modeling: Case Study from a Deepwater Field, Offshore Nigeria

Abstract The approach taken to integrate static data in reservoir modeling, varies along a spectrum from purely concept driven on one end to data driven on the other. Different methods can be adopted along this spectrum with varying levels of data integration and control. The method adopted usually depends on several factors including time available for the study, quality of data available etc. In this study, we contrast two methods along this spectrum to show the pros and cons of both. The study uses data from a mature field in deep-water Nigeria with over 16 years of production from 11 oil producers and eight water injectors. Declining field production and a depleting opportunity inventory necessitated a comprehensive study of the field and building of integrated reservoir models. The results from the field study will be the basis for drill-well and workover opportunity generation/maturation, water injection optimization and other value-added field depletion optimization strategies. A dual pronged approach was adopted for the reservoir modeling: A concept-driven approach involving representation of key reservoir architectural elements using object-based modeling (OBM) and use of qualitative seismic-conditioning to distribute key reservoir properties such as Net-To-Gross ratio, porosity etc.A seismic data-driven approach involving direct sampling of seismic inversion-derived properties into the model grids. Two distinct reservoir models were built and taken through model initialization, history-matching, and flow simulation. The history-matched model scenarios will be instrumental in generating production forecasts for field management and for infill well opportunity generation/maturation. This dual pronged approach enabled comparison of both modeling methods in terms of quality of match to existing static and dynamic data, reservoir characterization cycle time and achievement of field study objectives. The key learnings from the application of these two methods in a mature field and considerations for their application in other mature and green fields are the focus of this paper.