Calibrating Deepwater Depositional Models: Insights from Appraisal and Production of Stepped Slope Reservoirs, Offshore Nigeria

Ciaran J. O'Byrne, Mark Barton, Carlos Pirmez, and Bradford E. Prather
Technology Applications and Research, Shell International E&P, Houston, TX

Research over the last decade on flow process, slope characterization and dynamic interaction of topography with sedimentation has greatly advanced our understanding of complex reservoir architectures in deepwater slope depositional systems. Integration of quantitative observations from sub-surface and outcrop datasets with flume and numerical studies has provided some break-through insights on depositional response of sub-aqueous flows to sea floor topography and resultant preservation of reservoir targets in sand-prone channellised and unconfined depositional environments.

Our research in this regard has led to development of integrated depositional models and slope concepts, which help frame prospective deepwater reservoirs in context of slope type, position and depositional process to provide a detailed understanding of likely preserved reservoir architectures at any point on the submarine depositional profile. These models and concepts further form the framework for extensive internal databases of quantitative measurements of related architectural elements and statistics of heterogeneity distributions derived from multiple, high-resolution datasets. These data in turn are used in reservoir modeling scenarios to constrain static model realizations and for enhanced prediction of dynamic sweep efficiencies and ultimate recoveries.

This paper will use data from examples of currently producing reservoirs in offshore Nigeria as a calibration and validation of some of these slope concepts and depositional models. Application of these concepts in global exploration plays has resulted in significant cost-savings in appraisal and development planning and ultimately, will lead to more efficient exploitation of current and future reserves.

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