Using Experimental Design Table with Reservoir Simulation to Manage Sub- surface Uncertainties - A Niger Delta Case Study

摘要

Experimental Design (ED) methods are becoming a well- established alternative to traditional uncertainty analysis due to the fact that it offers a more efficient and consistent approach to identify and assess the impact of the key sub- surface uncertainties on field development decision. This paper describes a case study of applying ED to assess development risks in a gas reservoir in the Niger Delta. The reservoir is areally very extensive but relatively thin and underlain by aquifer. Key development and recovery risks were recognised to be access to pressure support and water breakthrough at the production wells. The objective of the study was to define realistic P10-P50-P90 sub- surface realisations and test various development concepts against this range of models to generate an optimal field development strategy. A multi step ED approach was used to understand and manage the key subsurface uncertainties. Alternative linear screening designs and multi-level response surface designs were used in this study. Key outcomes of the study were: - Successful demonstration of the application of Experimental Design technology and alternative screening designs - Generation of Response Surface models for In- Place and recoverable volumes. - Definition of a realistic range of sub-surface realisations for the reservoir and identification of P10-P50-P90 sub-surface models using Probabilistic (Monte-Carlo) analysis - Definition of key sub-surface uncertainties to be targeted for appraisal program - Generation of a robust range of production profiles and reserves estimates.