Mahmoud Zizi¹, Azzedine Jaboubker¹, Mustapha El Ktam¹
(1) ONAREP, Rabat, Morocco

Abstract: Paleozoic depositional system geology and play concepts

Exploratory drilling in the Paleozoic basin has established significant Paleozoic petroleum potential. The discovery of gas and condensate in the Essaouira basin, oil productions in the Sidi Fili trend and also the various oil and gas shows encountered in the Paleozoic rocks in number of wells drilled in Morocco, have stimulated the considerable interest in exploring and studying petroleum potential of the Paleozoic depositional system. Geochemistry analysis suggest that these hydrocarbon are generated from Paleozoic source rocks. They were trapped in structures which are essentially hercynian structures that were cut later in the Triassic by normal faults. The tectonic events responsible of the structuring of the Paleozoic beds are the passive margin stage which lasted from the Cambrian to Middle Devonian and was followed by the Upper Devonian to Carboniferous synsedimentary compression. The Middle Devonian time is known as period for the development of carbonate buildups. During this folding event, a series of ridges and depocenters took place. These ridges may have regional size such as the Western Meseta. This uplift introduced progressive unconformities, changes in thicknesses and variations in source and reservoir distribution during the Hercynian. All these geological considerations led to definition of new play concept that will make more attractive the Paleozoic series and minimize the risks in future exploration. The previous oil and gas discoveries in the country are to great extent related to the hercynian structures which were cut later by normal faults. This make the Paleozoic petroleum system viable. More similar prospects and larger are present and await to be tested.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana