New constraint on burial and thermal history of Devonian reservoir sandstones in the Illizi-Ghadames basin (North Africa) through diagenetic numerical modelling

The Illizi-Ghadames basin (located in Libya, southern Algeria and Tunisia), is one of the most prolific hydrocarbon regions in North Africa, and even though it has been intensely studied, the potential thermal effects of Cenozoic magmatic activity on the petroleum system are still debated. Here, the thermal history in a sector of the basin is investigated through petrographic observations and modelling of the diagenetic evolution of the Devonian sandstone reservoir. The thermal modelling scenario that best fits the petrographic and petrophysical observed data shows that overheating of the studied part of the basin occurred during the late Cenozoic, Miocene to Quaternary magmatic cycle. This implies that after the early drop in porosity and permeability, mainly due to compaction during the late Paleozoic, there was another significant decrease in reservoir rocks pore space during the late Cenozoic due to rapid quartz cement precipitation likely triggered by magmatic overheating.