Total-Property Modeling: Dispelling the Net-to-Gross Myth

Abstract

Summary Reservoir-modeling practice has developed into a complex set of numerical algorithms and recipes for modeling subsurface geology and fluid flow. Within these workflows, a number of myths have sometimes been propagated, especially in relation to (a) methods for handling net-to-gross (N/G), (b) implementation of upscaling methods, and (c) conditioning of reservoir models to well data. This paper discusses different practices in the use and upscaling of reservoir data and models, by comparing two end-member approaches: (1) the N/G method and (2) total-property modeling. Total property modeling, in which all rock elements are represented explicitly, is the generally preferred method. The N/G method involves a simplified representation of reality, which may be an acceptable approximation. Implications for upscaling and conditioning reservoir models to well data are discussed, and recommended practices are suggested.