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Abstract: Focusing Stochastic Simulation for Effective Problem-Solving in Reservoir Engineering

Richard J. Norris

The use of stochastic simulation techniques in modern reservoir description has produced 'faithful believers' and 'ardent non-believers'. The polarity of views usually acts to the detriment of the ultimate effectiveness of stochastic reservoir modelling techniques. On the one hand, if the non-believers hold sway, heterogeneities or uncertainties may be ignored in cases where their impact is, in fact, important. Conversely, if the believers hold sway, complex solutions may be used for less-than-worthy problems; alternatively, one may finish with results well below the promised level of complexity due to mundane time/budget constraints.

Whichever direction 'wins' within a given company or department, it is the reservoir management that loses. Stochastic simulation of reservoir heterogeneities is a very powerful set of tools which can often aid in reservoir description, and hence in reservoir simulation and management. To be credible, it is important that the tools are used in a manner which maximises their benefits, whilst minimises the costly 'over-kill' potential.

This paper presents a simple definition of the three main strengths of the stochastic simulation approach to reservoir description: integration of data; detailed modelling of heterogeneities; and quantification of uncertainties.

Through an understanding of how these three elements can be combined in different ratios, realistic solutions to specific problems can be developed. Practical applications of these ideas are presented through a series of case studies. The brief case studies are reviews of the reservoir characterization problems encountered and descriptions of the made-to-measure geostatistical solutions.

Through careful analysis of the reservoir problems and careful construction of appropriate solutions, stochastic reservoir modelling can better fulfill its promise. We might eventually escape from being believers/non-believers, into being objective users of a powerful tool.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela