A Practical Seismic Attributes' Workflow for Natural Fractures' Characterization of Tight Reservoirs in Algeria

In this paper, a new workflow of geometrical seismic attributes for a structural geological study has been proposed. The small faults with low throw were detected, and the natural fractures' model has been obtained for tight reservoirs. The fractures model has been correlated with imagery data taken from exploration wells in the studied field. The proposed attributes allowed us to map major faults with a throw less than the seismic resolution, and the curvatures have also been used to map subtler folds and flexures and overlying other formations. The geometrical seismic attributes used are: Curvature, Variance, Chaos, Structural smoothing, Edge enhancement, and Ant tracking. Moreover, the effectiveness of the proposed methodology has been demonstrated through the case study of Ain Amenas tight reservoir. The obtained results have been compared to conventional seismic interpretation results, for which it was demonstrated the existence of small faults that cannot be seen by the old methodology. Therefore, the constructed fracture model has been correlated and matched to the results of imagery interpretation of data taken from wells in the field. Finally, a relationship between fracture density and the attributes has been proposed in order to be considered for reservoir model construction in the production phase. This workflow can be useful in the optimization strategy of exploration costs of hydrocarbon resources of oil and gas national companies. The main novelty of this study is that it provides a practical workflow tool for continuous fracture modeling (CFM) and its successful application to several projects.