Oligo-Miocene reservoir sequence characterization and structuring in the Sisseb El Alem-Kalaa Kebira regions (Northeastern Tunisia)

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• 作者：Faten Houatmia^a ; ^{fatenhouatmia@yahoo.fr" class="auth_mail" title="E-mail the corresponding author} ; Sami Khomsi^b ; Mourad Bé ; dir^a
• 关键词：Basin structuring ; Siliciclastic reservoir ; Oligo-Miocene ; Seismic stratigraphy ; Tectonics ; Reserve volumes
• 刊名：Journal of African Earth Sciences
• 出版年：2015
• 出版时间：November 2015
• 年：2015
• 卷：111
• 期：Complete
• 页码：434-450
• 全文大小：11448 K

文摘

The Sisseb El Alem-Enfidha basin is located in the northeastern Tunisia, It is borded by Nadhour – Saouaf syncline to the north, Kairouan plain to the south, the Mediterranean Sea to the east and Tunisian Atlassic “dorsale” to the west. Oligocene and Miocene deltaic deposits present the main potential deep aquifers in this basin with high porosity (25%–30%).

The interpretation of twenty seismic reflection profiles, calibrated by wire line logging data of twelve oil wells, hydraulic wells and geologic field sections highlighted the impact of tectonics on the structuring geometry of Oligo-Miocene sandstones reservoirs and their distribution in raised structures and subsurface depressions. Miocene seismostratigraphy analysis from Ain Ghrab Formation (Langhian) to the Segui Formation (Quaternary) showed five third-order seismic sequence deposits and nine extended lenticular sandy bodies reservoirs limited by toplap and downlap surfaces unconformities, Oligocene deposits presented also five third- order seismic sequences with five extended lenticular sandy bodies reservoirs. The Depth and the thickness maps of these sequence reservoir packages exhibited the structuring of this basin in sub-basins characterized by important lateral and vertical geometric and thichness variations. Petroleum wells wire line logging correlation with clay volume calculation showed an heterogeneous multilayer reservoirs of Oligocene and Miocene formed by the arrangement of fourteen sandstone bodies being able to be good reservoirs, separated by impermeable clay packages and affected by faults. Reservoirs levels correspond mainly to the lower system tract (LST) of sequences. Intensive fracturing by deep seated faults bounding the different sub-basins play a great role for water surface recharge and inter-layer circulations between affected reservoirs. The total pore volume of the Oligo-Miocene reservoir sandy bodies in the study area, is estimated to about 4 × 10¹² m³ and equivalent to 4 × 10⁹ m³ of deep water reserves.