The field, a Late Ordovician gas condensate reservoir located in the Illizi Basin of the Algerian Sahara Desert, was put on production 6 years ago. It is the off-centred gas cap of a greater oil reservoir whose production was initiated by Sonatrach in 1967. The reservoir is characterised by its extreme geological complexity. The Late Ordovician (Unit IV) corresponds to a glacial period in the Saharian Basins. The heterogeneity of the reservoir -especially the strong variations in thickness -is such that it is extremely difficult to predict the performance of new wells, even when located in a well developed area. The presence of fractures organised in corridors increases even further the reservoir complexity. This paper presents the ways in which those challenges have been tackled in order to obtain both a reliable geological and dynamic model. It is shown how this characterisation was made possible by the integration of all the available information: seismic, geological and dynamic data.The matrix modelling was performed though the definition of electrofacies. Outcrop observations, depositional models as well as seismic data were used to define the internal layering of the geological model.The fracture model was achieved by integrating the curvature of the top reservoir horizon. It was confirmed and refined through comparison with borehole imagery (BHI) logs and dynamic data (mainly well tests and historical production data). Fracture conductivity was adjusted such that well productivity was respected. The outcome was a Discrete Fracture Network (DFN) model that was then upscaled and integrated into a single medium dynamic model.The final outcome is a dynamic model in which the history matched process was greatly improved. The predictability of the model was tested in an under-developed area of the field where new wells have recently been drilled. A fairly good agreement between the model and the reality was found in areas already appraised. In completely undeveloped area, the model was less successful.
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