Geomechanical Heterogeneity in channelized systems — How much is enough?

Abstract

The accurate prediction of reservoir compaction and surface subsidence is critical for safe and efficient field development but is often delayed until a detailed reservoir characterization is available. This study investigates whether simplified three-dimensional geomechanical models based on bulk compositional parameters, instead of detailed geological models, can predict compaction and subsidence in channelized sandstone reservoirs. Through direct numerical simulation of an ensemble of synthetic channel systems with varying geometries and facies distribution, and statistical analysis of effective mechanical properties, we demonstrate that shale content is the primary control on the effective Young's modulus of a sand–shale sequence, with the channel geometry having only a minimal impact on the effective modulus. Statistical analysis reveals that a model based primarily on shale fraction can predict effective Young's modulus with high accuracy, while channel geometry parameters contribute to less than 5% to the prediction. Field-scale finite-element simulations confirm that simplified models using bulk shale content produce compaction and subsidence predictions comparable to detailed models with explicit channel representation, while significantly reducing computational and modeling requirements. Our findings enable earlier integration of geomechanical considerations in field development planning by demonstrating that detailed channel characterization, often unavailable in early project stages, is unnecessary for reliable geomechanical predictions.