A new approach to shale management in field scale simulation models

Abstract

Virtually every sandstone reservoir contains significant amounts of shale. While the sand/shale sequence in the wells is known, a reliable reservoir description must quantitatively answer the following questions: What is the lateral continuity of the shales. How are the shales distributed in unsampled areas. What are the effects of the shales on transport properties. This paper presents statistical techniques by which the lateral continuity and spatial disposition of shales can be estimated. These techniques rely on shale statistics from the wells, and outcrop statistics from appropriate depositional environments. The resulting shale description can be conditioned to honor the observations in the wells. The subsequent discretizing of the reservoir into grid blocks for numerical simulation yields large elemental units which usually contain both sand and shale. The paper concludes by showing how the permeability and porosity may be estimated from the disposition of shales within each block.