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AAIUN BASIN The Aaiun Basin in the Western Sahara is a large
Mesozoic and Tertiary age basin, over 800 kms long and up to 300 kms wide, and lying both onshore and offshore. The Aaiun
Basin has a total area of 235,000 square kms, including the offshore area out to the continental shelf break. A further 80,000
square kilometers of continental slope down to the abyssal plain are also underlain by sedimentary rocks prospective for hydrocarbons.
The
biggest phase of hydrocarbon exploration in the Aaiun Basin was mostly onshore in the early sixties. A total of 70 wells were
drilled by 14 different operators in the basin (one exploratory well per 3,300 square kms). Towards the end of this phase,
five offshore wells were drilled by Gulf, Conoco and Enpasa. Other than a few marginal shows in one onshore well drilled by
Gulf (well A1-47, located on the Bojador Block), and some oil in Jurassic rocks in the Cap Juby structure (drilled by Esso)
offshore from Tarfaya in Morocco, very little encouragement for hydrocarbon exploration was generated from the drilling in
the initial phase.
The onshore and offshore drilling, as well as seismic, in the Mesozoic Aaiun Basin has proven the
occurrence of all the elements of a petroleum system. The existence of good reservoir rocks, potential mature source rocks,
and structure creating traps are relatively well documented, but other elements such as hydrocarbon generation, migration
timing and pathways, and actual entrapment, are still poorly defined.
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