Reservoir Characterization and Coupled Reservoir-Geomechanical Simulation of CBM Using GSI - Case Studies

Abstract

Abstract A hydro-geomechanical coalbed methane reservoir characterization workflow is reviewed and applied to three field cases from the same coalseam formation. The workflow begins from core sample characterization and ends at reservoir performance. A core sample and geophysical logging rock mass characterization approach using the newly adopted Geological Strength Index (GSI) is used. GSI was developed for Civil Engineering tunneling projects to characterize fractured rock masses and is adopted here with new functions to related GSI to observed Young's modulus and then included for permeability changes during production. The GSI characterization is applied to three separate reservoir geomechanical simulation models with separate and distinct production profiles. Reservoir and geomechanical data to populate the models comes from three sources: Nexen, the University of Alberta, and the Alberta Energy Regulator. The significance of this study is to investigate the influence of geomechanics on well productivity for fractured reservoirs using a common geological parameter which relates fracture intensity to mechanical properties.