Fatoke, Oluwaseyi Adedamola¹, Denis Chantreau¹, Mona Kalu¹, Muyiwa Awojuyigbe¹, Fred Osoro¹
(1) Shell Nigeria, PortHarcourt, Nigeria

ABSTRACT: Geological Uncertainty Management in Integrated Reservoir Modeling Studies: Example from Onshore Niger Delta

The nature of the subsurface and limitation of subsurface data makes uncertainty analysis and management an integral part of any integrated reservoir modeling study workflow. Study deliverables-volumes, forecasts, optimal development plans, etc. are intrinsically influenced by geological uncertainties and how such uncertainties are handled is fundamental to any integrated work. Various methods are available for handling these static uncertainties. These methods range from statistics to geostatistics, from probabilistic to deterministic approach.
Scenario based approach is generally the recommended approach for handling static uncertainties in reservoir study. In an unconstrained world numerical simulation of identified scenarios is ideal. However, time and resources constraints are realities of the E & P business.
In this paper we present a pragmatic scenario based uncertainty handling approach for integrated reservoir modeling studies. The approach involves – integration and analysis of all available subsurface data at study kick-off, identification, impact assessment and ranking of all likely subsurface uncertainties and the development of a fit for purpose, focused uncertainty management strategy for the uncertainties that has significant impact. This method allows the team to decide early, on how best to handle the uncertainties-sensitivities or full alternative scenario modeling. It also allows for re-ranking of uncertainties as the study progresses.
The benefits of this approach are that it allows for better data integration, reduction in integrated study time and provides a roadmap for achieving study deliverables without jeopardising quality.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.