A systematic analysis of petroleum system criticals can provide a robust review of a basin's hydrocarbon potential through time and space. The ten essential petroleum system criticals that express the extensive and intensive variables are: source generation volume (Sgv), source-rock richness (Sgr), source-rock quality (Srq), source-rock maturity (Srm), reservoir rock volume (Rrv), reservoir rock quality (Rrq), reservoir rock hydrocarbon type (Rrhct), reservoir rock seal and closure (Rrsc), flux migration path (Fmp) and petroleum system timing (PSt). The Matruh–Shushan Basin of the Western Desert, Egypt, forms the basis for an example of the application of this technique.
Modelling and empirical data of source-rock criticals reveal that the Mesozoic source generation megasequence is restricted in the Matruh–Shushan Basin. Presently, these areas lie buried at their maximum experienced temperatures. Potential reservoirs in portions of the north and central Western Desert were dependent upon lateral migration path criticals for their charge. Progressive uplift and basin inversion since the middle Palaeozoic provided favourable conditions for lateral migration in the Mesozoic. The main potential source rocks in the present basins are the Lower Cretaceous Alam El Bueib (AEB) and the Jurassic Khatatba. Although both share mixed kerogen types (II/III), they attained their highest levels of thermal maturity at different times. Basin modelling suggests the Lower Cretaceous AEB entered the oil window in the Late Cretaceous, while the Jurassic Khatatba of the deeper part of the basin entered the oil window in the Turonian.
Charge risks increase in the deeper basin megasequences in which migration hydrocarbons must traverse the basin updip. The migration pathways were principally lateral ramps and faults which enabled migration into the shallower post-Late Cretaceous structured reservoirs.
Basin modelling incorporating an analysis of the petroleum system criticals has outlined the spatial and temporal extent of the different petroleum systems in the Matruh–Shushan Basin and can help guide the next exploration phase. While oil exploration is now focused appropriately along Late Cretaceous and Tertiary migration paths, these results suggest deeper sections may have reservoirs charged with significant unrealized gas potential.
- 2005 EAGE/Geological Society of London