Dynamic impact and flow-based upscaling of the estuarine point-bar stratigraphic architecture

Abstract

Abstract The estuarine point-bar architecture – one of the main sub-depositional environments of tide-dominated shallow-marine and fluvial (SM&F) systems – constitutes one of the most shale-prone clastic reservoir architectures potentially posing risks to the production performance. A set of simulation-based sensitivity studies quantify the effects of a number of stratigraphic and reservoir engineering parameters on the dynamic connectivity of the confined estuarine point-bar architecture. Water injection recovery mechanism is utilized for polarizing the stratigraphic and reservoir engineering parameters in terms of their effects on hydrocarbon recovery. The point-bar shale-drape architecture and abandonment channel attributes (e.g., permeability, facies composition, and shale-drape coverage) dominate the dynamic reservoir connectivity, hence the recovery factor and water breakthrough time/profile. In terms of reservoir engineering parameters, well spacing and, to some degree, relative mobility ratio constitute the factors of importance for the investigated model parameter ranges. The dynamic effects of intra-facies permeability heterogeneity are evaluated using a number of realizations comparing them to those stemming from facieswise-homogeneous realizations. Results indicate that intra-facies permeability heterogeneity influences the connectivity factor for low shale-drape coverage levels. For high coverage levels, presence of shale drapes almost completely overshadows the influences of intra-facies permeability heterogeneity. A novel multiphase flow-based upscaling method, specifically developed for clastic reservoirs containing long-correlation-length permeability heterogeneity, is evaluated first-time on the scale-up of the estuarine point-bar architecture. Resulting coarse-scale models capture the fine-scale dynamic behavior with an accuracy level that is significantly higher than those obtained by use of single-phase flow-based upscaling.