1 ) Overview
The Ouarzazate basin covers an area of 5 407 Km². It is a foreland basin related to the uplift of the High Atlas folded belt.
This basin is limited to the north by the High Atlas Mountains, to the west by the ancient massif, to east, by the oriental Anti Atlas and to south, by the Saghro Paleozoic inlier.
2 ) Data base
About 464 Km of multi fold 2D seismic data is available in the basin and two stratigraphic wells drilled in the southern margin of the basin.
3 ) Tectonic and Sedimentary Evolution
The southern margin of the basin consists of Neogene sediments which unconformably cover a gently northerly dipping Precambrian basement. The northern margin of the basin was subjected to alpine folding and faulting which involve the Jurassic to Neogene beds. In the central and southern part of the basin, the Mesozoic sequence pinches out against the Paleozoic beds below the Neogene sediments.
The Paleozoic series were subjected to the Hercynian deformation. The Mesozoic becomes less deformed from North to South within the basin.
4 ) Petroleum system
The presence of excellent source rocks and good potential reservoir rocks in the surrounding outcrops make this basin attractive for petroleum exploration.
4-1 ) Source rock
All the source rock information was provided by surface studies from surrounding outcrops.
The Paleozoic main source rock is the Silurian black shales (average TOC from 3.55% to 11 %). Ordovician and Carboniferous shales may be considered as additional source rocks. The organic matter could be type II and or III and the Silurian maturation is variable from mature to slightly mature.
The Mesozoic source Rocks may also be considered (Liassic source similar to MK 1 well black marls in Boudenib basin and the Cretaceous/Paleogene succession similar to Tadla basin). In the same way, the Oligo Miocene maturation scenario, related to a tectonic stacking of imbricates in the Tadla basin, could be also apply to the Ouarzazate basin and present attractive Atlasic structures.
4-2 ) Reservoir Rocks
In the absence of direct subsurface observations, Ordovician, Carboniferous, Triassic-Liassic and Dogger sandstones are considered to be the potential reservoir rocks in the basin.
The Cenomano‑Turonian carbonates may also be considered as potential reservoirs because they are overlain by a relatively thick Senonian, Paleogene and Miocene sedimentary succession.
4-3 ) Seals
Shaly beds, present in the Paleozoic section and shaly‑ saliferous beds in the Mesozoic section constitute an adequate seal.
4-4 ) Traps
Two kinds of traps have been identified within the basin, structural and stratigraphic.Structural traps are: thrust anticline, fault traps, tectonic imbricates.Stratigraphic traps are: clastic lenses, lateral facies changes and pinch out related to unconformities.
5 ) Play Concepts
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Subthrust plays concepts (thrust anticlines, fault traps, tectonic imbricate) which involves the Mesozoic succession.
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Deep and large Paleozoic structures.
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Stratigraphic traps: clastic lenses (Visean turbidites, Triassic fluviatil channels); lateral facies changes; porosity barriers in carbonate formations (Cenomano‑Turonian, Liassic, Carboniferous, Devonian, etc...).
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Basin
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Ouarzazate
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Basin type
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Paleozoic basin
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Area
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5 407 Km²
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Exploratory wells
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0
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2D Seismic/3D Seismic
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464 Km of 2D
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Source Rocks
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Silurian, Ordovician & Carboniferous
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Reservoir Rocks
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Ordovician, Carboniferous and Triassic sandstone
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Seal Rocks
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Shale
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