Characterization of Fractured Reservoir
Jon E. Olson
Predicting the performance of fractured reservoirs requires characterization of fracture length, spacing, height and aperture distributions. Because none of these parameters are typically well constrained by available subsurface data because of small sample size (wellbores) or indirectness of the measurement (seismic), theoretical models are required to fully populate fracture networks for flow simulation.
Our approach is to combine insights from the limited geologic observations and core mechanical properties with a fracture mechanics-based model to predict fracture network attributes. We import these fracture networks into a reservoir simulator to discover the key attributes that control production behavior to help further guide characterization efforts. The development of the geomechanical model is linked to fracture mechanics measurements on core, fracture network characterization at outcrop analogs, and the influence of diagenetic history on rock mechanical properties and fracture aperture. Flow simulation work has discovered fundamental relationships between permeability and fracture attributes such as length distributions and connectivity, providing more realistic estimates than the idealized parallel-plate model.