Reservoir Characterization and Modeling of the Upper Ordovician Sandstones Unit in Southwestern Sahara, Algeria

In the southwestern part of the Algerian Sahara platform, the production of dry gas from Ordovician reservoir is related not only to lateral facies changes but also to the spatial distribution of natural fractures throughout the reservoir. In order to check out these assumptions, an integrated approach using a large data set, and combining several methods is used to simulate separately porosity, subseismic fault and fractures models. The main data integrated, derived from core, outcrop, wire-line logs, seismic interpretation, seismic attributes and PVT. The different concepts and approaches are related to sedimentological and structural aspects, geostatistics, sequence stratigraphy, seismic stratigraphy, and attributes generation. This leads to generate acoustic impedance which is integrated in the porosity simulation workflow as a secondary propriety, by using deterministic methods. The subseismic fault model is carried out by the means of a specific workflow, smoothing, variance and antracking attributes generations. The analysis of distribution of these subseismic faults throughout the main study field shows a closer relationship between fractures density, the curvature axes of the folds and the productivity. All these results have an impact on the planning of the future delineation wells and in the exploration-production strategy.