--> --> LATE CRETACEOUS RESERVOIRS CHARACTERIZATION OFFSHORE SFAX-MAHDIA REGION- TUNISIA

AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin

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LATE CRETACEOUS RESERVOIRS CHARACTERIZATION OFFSHORE SFAX-MAHDIA REGION- TUNISIA

Abstract

The study area lies on the pelagian platform where the Late Cretaceous sediments present one of the largest hydrocarbon reservoirs in Tunisia. An integrated study mainly based on the lithostratigraphic description, well correlation and sequence stratigraphy analysis from drilled wells and 2D seismic reflection has been conducted in order to characterize the main reservoirs. During late Cretaceous, extensive shallow water carbonate platforms were developed over offshore Sfax-Mahdia. Seismic interpretation characterized NW-SE directed horst and grabens. The application of sequence stratigraphic methods on well logs was performed in order to organize the basin fill into a set of system tracts. As for petroleum systems, the Late Cretaceous reservoirs are sourced by Bahloul and Zebbag Formations. Well to well correlations and the established lithostratigraphic chart show that tectonics played a key role in controlling sedimentation on the Eastern offshore basin, leading to rapid lateral facies changes in response to differential basement subsidence. The petrophysical characteristics generated from well log reveal that the reservoir quality is influenced by microfacies distribution, reservoir texture and burial history. Several unconformities affect the stratigraphic column in the study area and have been interpreted as related to compressive events. These tectonic events have resulted in the development of structural and stratigraphic traps further to the porosity and permeability enhancement of reservoirs.