1 ) Overview
The Boudenib basin is located south of the High Atlas. It is bordered on the east by the Bechar basin, to the south by the Hamada du Guir and on the west by the Anti-Atlas outcrops. Boudenib basin covers an area of around 43 819 km².
2 ) Data base
From 1977 to 1981 about 1649 Km of multifold 2D seismic lines have been acquired.
Tethys oil acquired new gravity and magnetic data covering 1536 km². Six wells were drilled in the area between 1950 and 1987. Two wells encountered oil shows in Liassic limestones and gas show in the Paleozoic.
3 ) Tectonic and Sedimentary Evolution
From Middle Cambrian to the end of Ordovician, a shaly to sandy sedimentation took place followed by black and green shale deposits during Silurian.
Up to the Middle Devonian, sedimentation remains essentially shaly to silty with interbeds of clastics or carbonates related to shallow water environment.
During the Late Devonian, series of ridges and depocenters took place due to the early hercynian compression. This uplift introduced changes in thicknesses, and facies.
In Carboniferous time, the sedimentation was dominated by shale with interbeded sandy layers. After the Hercynian orogeny, the central and eastern part of the basin emerged, until the Cenomano-Turonian transgression when marine sedimentation took place in topographically low areas.
Later in the Oligocene time, under the effect of Atlasic compressive tectonics, these troughs were gently folded and faulted toward the south.
4 ) Petroleum system
4-1 ) Source rocks
The main source rock is formed by Silurian black shales (average TOC ranging from 3.8% to 12. %). A few Ordovician and Visean shaly levels also present interesting source rocks characteristics. Siluro‑Ordovician source rocks are type I and II and Carboniferous formations are type III.
4-2 ) Reservoir Rocks
The main reservoirs rocks are: late Ordovician sandstone, middle Devonian reef (porosity is ranged between 4 to 12%) and Carboniferous sandstone (porosity is ranged between 7 to 12%). The potential reservoirs are: late Devonian fractured carbonate and Visean reef.
The fractures (joints) are highly developed, opened and dense and could enhance the quality of reservoirs.
4-3 ) Seals
The main seals are: Silurian, lower Devonian and thick interbeded carboniferous shale. Potential seal occur in the Mesozoic, (Lias Dogger shaly and anhydritic formations).
4-4 ) Traps
Both structural and stratigraphic trap are present in Boudenib basin.
The stratigraphic traps are within the Devonian reefs, Carboniferous turbiditic sandstones and pinch out below the carboniferous unconformity.
The main structural traps are hercynian anticline and related faulted block. Other important structural and stratigraphic trap is folded paleo-high with related reef development.
5 ) Play Concepts
The Palaeozoic play is represented by Middle-Upper Devonian objectives charged by Lower Devonian and Silurian source rocks and capped by a Carboniferous shaly succession.
6 ) Prospects and leads
Two main prospective zones are identified in the area.
- Paleozoic prospective zone in the central and eastern part of the basin with a number of leads defined in the Devonian platform and slope. In the central part of the basin, possible stratigraphic traps within the thick Carboniferous succession may exist.
- Jurassic prospective zone in the frontal subthrust of the High Atlas and in the most western part of the basin.
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Basin
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Boudenib -Erachidia
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Basin type
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Paleozoic basin
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Area
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43 819km ²
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Exploratory wells
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7
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2D Seismic/3D Seismic
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2.229,00 km of 2D
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Source Rocks
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Lower Ordovician, Silurian, lower
Devonian and Carboniferous
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Reservoir Rocks
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Silurian-Ordovician, upper Devonian and Carboniferous
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Seal Rocks
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Silurian, Early Ordovician, early Devonian and Carboniferous
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