Unconventional Reservoir Characterization with Geomechanical Attributs of Multi-az. Inversion - Barnett Shale Application

The development of the exploration and exploitation of unconventional hydrocarbons requires innovative techniques to allow a better characterisation of natural fracture networks and fracability of the rocks at depth. Within this context, a workflow of stratigraphic multi-azimuth prestack inversion is presented in this study. It was applied to a dataset imaging the Barnett Shale formation in a transition zone between the oil and gas windows. Four kinds of inversions were performed: poststack all azimuth, poststack multi-azimuth, prestack all azimuth and prestack multi-azimuth. Based on a geological a priori model, the multi-azimuth stratigraphic inversion consists in inverting azimuthal partial stacks. Anisotropy is then quantified through an ellipse fitting algorithm. The Poisson's ratio and a brittleness coefficient are derived from the prestack inversion results. Some areas within the Barnett Shales present low Poisson's ratio and high brittleness, corresponding to potentially high fracability zones. The results also show azimuthal variations in the geomechanical attributes explained by the nature of fluid contents and by the presence of fractures.