Relevant reservoir characterization: Recovery process, geometry, and scale

In this paper, we consider the role of hydrocarbon reservoir description in the context of the specific recovery process that is of interest. Both deterministic and stochastic representations of reservoir heterogeneity are considered. The relevance of different features of these representations is considered for two important secondary and tertiary recovery processes, namely miscible-gas flood and waterflood (immiscible). We find that, with miscible-gas flood, large-scale geometry may be more important than the internal small-scale structure, whereas with waterflood, the small-scale structure is likely to be a dominant influence on recovery. There is no panacea for reservoir characterization, and the critical reservoir properties must be determined by considering both the fluid recovery mechanism and the interaction of this mechanism with the specific type of variability present in the reservoir system.