An overview of the petroleum systems of Morocco

Abstract

Abstract Magoon & Dow’s petroleum system concept is utilized in this paper to evaluate the origin of the proven hydrocarbon resources of Morocco, which lie chiefly in the Essaouria, Prerif and Rharb Basins. Several systems are interpreted, in which the confidence in the source-petroleum tie varies from ‘known’ to ‘speculative’, involving charge from Silurian (eastern Essaouira), Lias (Prerif), Oxfordian (western Essaouira), Cretaceous (Ain Hamra) and an intra-Miocene biogenic system in the Rharb Basin. The origin of the Cap Juby heavy oil accumulation in the offshore Tarfaya basin is uncertain, with a Jurassic carbonate source currently the favoured interpretation. The petroleum system concept is extended in this paper to predict further, currently undrilled and unproven systems. These include areas where the proven source systems referred to above are likely to extend, plus additional systems predicted on the basis of analogues to surrounding regions. An example of the latter is a series of postulated Triassic systems developed in lacustrine deposits in offshore half-grabens. Palaeozoic source rocks may be regionally developed and may still be in the oil and gas windows over wide, generally unexplored, regions. Lower to Middle Jurassic source rocks are predicted in lagoonal settings in platform sags and in outer shelf environments, whereas Cretaceous source beds occur in continental rift complexes and passive margins, with maturity likely to be reached in depocentres and below thrusts. Biogenic gas potential is probably confined to Neogene deposits in foreland and divergent margin basins. Further application of the petroleum system concept should help to significantly reduce geological risk, particularly in frontier exploration areas.