--> Abstract: Thermal Regime Hydrodynamics and Petroleum Occurrences in Tunisia, by H. Ben Dhia; #91012 (1992).

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ABSTRACT: Thermal Regime Hydrodynamics and Petroleum Occurrences in Tunisia

BEN DHIA, HAMED, University of Sfax, Sfax, Tunisia

The possibility that positive geothermal anomalies and hydrocarbon occurrences in deep sedimentary basins genetically related to formation-water flow has been suggested by various authors in recent years. These suggestions have been corroborated by several studies in central and the Saharan parts of Tunisia.

In central Tunisia, eight of ten known major accumulations are located within a region of positive geothermal gradient anomalies ranging from 35 degrees to 45 degrees C/km. It is noteworthy that temperature gradients are relatively low in the older (Triassic) reservoirs, while they are high in the Tertiary fields. The Douleb (Aptien) and Lytaiem (Ypresien) fields are located in areas of formation-water convergence and discharge. Other areas of flow convergence have been recognized from hydrogeological studies, but their oil potentials have not yet been assessed.

In the Saharan region, including parts of Algeria, background heat flux is approximately 80 mWm-2, whereas the actual values range between 60 and 141 mWm-2. The anomalies appear to be due to regional formation-water flow, with the low values being associated with recharge areas (Algerian Thinrhert and High Plateaux) and the high ones with discharge (Tunisian Jeffara and Algerian Tademait). The hydraulic perturbation of the normal heat flux is estimated to be on the order of 10 to 20 mWm-2. The main vehicle for the transport of both heat and oil appears to be, therefore, regional formation-water flow.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)