JENNINGS, J. SIMON, CHRIS CLAYTON , and ALASTAIR BAIRD, School of Geological Sciences, Kingston University, Penrhyn Road, Kingston-Upon-Thames, Surrey, UK, and ANTHONY FALLICK, Scottish Universities Research and Reactor Centre, Rankine Ave., East Kilbride, Glasgow, UK

Abstract: The Hydrocarbon Systems Within The Sidi El Kilani Field Of The Tunisian Atlas Foreland

In the N Kairouan permit, in the foreland of the Tunisian Atlas, hydrocarbons are produced at Sidi El Kilani from open and partially open fractures in the Campanian to upper Maastrichtian Abiod Formation micritic limestones. The analysis of over 1000 km of seismic data from the N Kairouan permit has led to the identification of a complex sequence of latest Cretaceous to recent fracturing events.

Petrographic analysis on fracture infills from Sidi El Kilani indicates that there have been several generations of dolomite and calcite cementation. Hydrocarbon fluid inclusions have been trapped within dolomite grains and these grains are occasionally enclosed within the calcite cements, illustrating that there have been at least some dolomite precipitation and coeval hydrocarbon flow prior to calcite cementation. A combination of fluid inclusion and stable C and O isotope analysis indicates that the carbonates precipitated from Mg-rich, Na-Ca-Cl basinal brines, with dolomite precipitation between 125°C and 160°C, and calcite precipitation between 75°C and 125°C.

Even though the polyphase fracturing events range from latest Cretaceous to recent, the burial history modelling of exploration well SLK-2, when integrated with the temperatures of homogenisation has constrained the timing of reservoir charging. Hydrocarbon emplacement occurred in the latest Miocene to earliest Pliocene, probably after latest Miocene subsidence and during subsequent rapid uplift.

AAPG Search and Discovery Article #90923@1999 International Conference and Exhibition, Birmingham, England