A variety of reservoir intervals have been encountered in wells throughout the sedimentary sequence.
Results are summarized as follows:
Palaeozoic
Within the Carboniferous succession, most reservoir intervals are encountered in the Westphalian, Namurian and Visean of the High Plateaux. These beds are mostly deltaic to turbiditic siliciclastics with porosity values around 11 %, reaching 15 % in the Missour Basin. Similar reservoirs may exist in the Tindouf Draa area. Visean carbonate reservoirs are also known in the High Plateaux and Tadla Basins.
Devonian reef carbonate reservoirs are expected in the Doukkala, Boudenib and Tindouf-Draa Basins. Cambro-Ordovician sandstone and conglomerate reservoir intervals are interpreted to have porosity enhanced by fracturing particularly in the Tadla and Tindouf-Draa areas.
Triassic
Triassic sands and conglomerates are widespread over most Moroccan sedimentary basins. In most cases they were deposited in fluvial and deltaïc environments. Porosity values average 10 % in the Tadla, and High Plateaux and may reach 15 % in the Doukkala and 22 % in Essaouira Basin.
Jurassic
Numerous reservoirs are known in the Jurassic succession. They are : (1) reef carbonate in the Missour Basin with porosity up to 10 %, (2) the Tarfaya Laayoune carbonate, (3) sandy dolomite and carbonate of the Callovo-Oxfordian in the Essaouira Basin, where the porosity range from 5 to 20 %, (4) the Middle Jurassic arkosic sand of the Haricha, with porosity of up to 30 % , (5) the Middle Jurassic sands in the Tadla Basin (porosity up to 10 %), (6) the Lower Jurassic carbonate in the Guercif Basin, the reef carbonates in the High Plateaux, the oolitic limestone in the Tselfat and the coarse sandstone in the Sidi Fili trend. Porosity values of the Lower Jurassic reservoirs range from 10 to 30 %.
Cretaceous
Upper Cretaceous reservoirs are encountered in the Tadla Basin. These include Cenomano-Turonian Carbonate and Senonian sands, with porosities around 10 %. Much better intervals are encountered in the Cretaceous of Tarfaya-Laayoune Basin where the porosity ranges from 20 to 30 %.
Neogene
In the onshore basins, the Neogene sequence contains good to excellent reservoir intervals. These are: (1) Oligocene sands in the Rif domain, with porosity ranging from 15 to 20 %, (2) Miocene sand in the Rharb Basin, with porosity of up to 30 %, (3) turbiditic sands in the Meso-Rif with porosity values of up to 17 %, and (4) sands and conglomerates of the melange (Prérif nappe) and the sands underlying the melange. These reservoir intervals have yielded porosity values ranging from 8 to 20 %. |