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1 ) Overview
The Prerif-Mesorif area is a part of the Rif mountains folded belt which is the product of the collision of the African plate and the Alboran micro plate. The Rif’s chain extends from the Tangier peninsula to Melilia Bay to the east. To the South, this domain is limited by the Gharb, the Saiss, the Guercif and the Beni Znassen-Beni Bou Yahi forelands.
2 ) Data base
- Seismic data: The Prerif-Mesorif basins are covered by more than 5000 Km of 2D seismic lines. The quality of these data is variable ranging between a very good seismic quality in the southern flank of the Rides prérifaines and medium to poor seismic quality in the central parts of the Prerif, due probably to distortion and dispersion of seismic pathways.
- Wells data: About 30 exploratory wells have been drilled in the Mesorif and the Prerif basin. The last seismic programme was shot in 2007 (205 Km) in Ouezzane area. The first 3D seismic, of a total of 162 Km² has been acquired in the areas between Harich, Tselfat and Boudraa.
3 ) Basin fill and geometry
Sedimentary fill consists of more than 6000 m of Mesozoic and Cenozoic sediments overlain by the complex of the Prerif nappe itself is covered by Tertiary clastic sediments.
4 ) Petroleum System
4-1 ) Source Rock
The Prerif basin produced hydrocarbon from Mesozoic and Cenozoic series. Two main source rocks of good geochemical quality are developed within the Meso-Prerif zones: A lower Jurassic source rock, developed during the Toarcian-Domerian time, is at the base of Bodraa oil field and Haricha oil and gas field. The second source rock is Upper Cretaceous in age (Cenomanian / Turonian). It is interpreted to be the source for Ain Hamra and Tselfat oil fields.
4-2 ) Reservoir Rocks
Reservoir rocks have been deposited during the Mesozoic and Cenozoic times. Although no commercial accumulation has been tested yet, oil and gas shows were recorded in the Triassic sandstones and dolomites. Carbonates and oolithic limestones, deposited during the lower Jurassic, could have good porosities and constitute reservoir for oil accumulation. Middle Jurassic and Upper Jurassic deltaic to turbiditic sandstones are considered to be the main reservoirs in the Meso-Prerif basins. Cenozoic sandy reservoirs are also present within piggy back basins in the central parts of the Prerif.
4-3 ) Seals
Seals are provided by the marls deposited during the Toarcian time for L. Jurassic reservoirs and the complex of nappes for Middle and Upper Jurassic sandstones.
4-4 ) Traps
Mesozoic objectives are presents in mainly structural traps (subthrust and over thrust structures). Stratigraphic (sand lenses) and structural traps (faulted and folded blocs) could also be considered for Upper Miocene objectives.
5 ) Play Concepts
The developed play concepts lie to:
6 ) Prospects and leads
The Prerif was a hydrocarbon producing province from the nineteen thirties to the fifties. A number of oil and gas fields were discovered. Recent geological investigations and a new seismic grid show that more oil may be discovered in plays similar to the producing ones, and in plays which have not been yet tested such as old salt structures, subthrust and over thrust traps.
7 ) Production History
A total of 12 fields have been discovered in the southern flank of the Meso-Prerif basins. Cumulative production reached nearly 11.2 MMbbls of oil and 7.31 Bcf of gas.
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Basin
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Prerif - Mesorif
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Basin type
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Folded Belt
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Area
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39 868 Km²
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Exploratory wells
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31
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Gas and oil discoveries
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Haricha- Boudraa-Tselfat-Sidi Fili fields
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2D Seismic/3D Seismic
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7.001,00 Km of 2D / 175,00 Km² of 3D
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Source Rocks
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Toarcian-Domerian; Cenomanian-Turonian
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Reservoir Rocks
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oolithic limestones from Lower Jurassic; Middle Jurassic and Upper Jurassic deltaic to turbiditic sandstones; Cenozoic sandy reservoirs
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Seal Rocks
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Marls from Toarcian and the complex of nappes for Middle and Upper Jurassic sandstones
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Hydrocarbon type
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Oil and gas
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