• The data base so far available has permitted the delineation of the following facies as potential source rocks:

    Palaeozoic

    The Ordovician, Silurian and Devonian organic facies are predominantly sapropelic (type II kerogen) although, in places, these facies are becoming lipidic (type I kerogen). These Palaeozoic organic facies are widespread over the whole Moroccan territory and constitute the continuation of those encountered in Algeria and North Africa in general. The Carboniferous organic facies, however, is predominantly humic (type III kerogen). The Silurian source rocks with TOC value of up to 12 % (Tadla Basin) are the most important. The Ordovician and Devonian sequences exhibit interesting source rock intervals with TOC values in the order of 4 % in the same basin. Visean and Namurian sequences contain shaly intervals with humic organic facies (type III kerogen) having TOC values around 1.5 % in the High Plateaux. Similar facies are also encountered in the Tadla Basin. The Westphalian and the Stephano-Autunian organic facies with frequent coaly and lignitic intervals yielded TOC values in excess of 30 % in the High Plateaux and Argana valley. Some oils sampled from reservoirs or well shows in the Prerif (Tselfate field), Doukkala, Tadla, and Essaouira basins are interpreted to be generated from Palaeozoïc source rocks.

    Triassic

    The synrift sequence, infilling Triassic graben and half graben along the Atlantic coastal basins, may yield excellent lacustrine (type I kerogen) source rock. These intervals have been tested in the Doukkala Basin. TOC values are in the order of 2.5 %.

    Jurassic

    Recent geochemical survey shows that the Rif, the Middle and the High Atlas basins contain rich Lower Jurassic (Liassic) source rock. The organic facies is predominantly amorphous type II kerogen with TOC values up to 10 % and within the oil window in most places. This facies is producing oil in the Prerif Ridges and is the source for many seeps distributed throughout the Prerif and the Middle Atlas areas. The petroliferous character of this Jurassic organic facies may have a widespread distribution. The oil at Sidi Rhalem field in the Essaouira Basin is produced from Oxfordian shale (TOC up to 4 %). The oils produced in the Cap Juby structure in the Tarfaya Basin were probably sourced from Jurassic marly facies. In the Tarfaya-Layoune-Dakhla Basin, Lower and Middle Jurassic organic facies have TOC values ranging from 1.47 to 2.49 %.

    Cretaceous

    Marine organic facies (Aptian-Albian and Cenomano-Turonian) are, by far, the richest in organic matter with TOC up to 20 %. These facies are widespread over most of Moroccan sedimentary basins. Under adequate burial, the Cretaceous marine organic facies may constitute an excellent effective source rock. Recent synthesis shows that this could be the case in the Rif, Tadla and, basinward, in the offshore Atlantic basins

    Neogene

    the Neogene (Oligocene and Miocene) marls and shales have TOC values of up to 7 % in the Atlantic basins and up to 2 % in the Mediterranean offshore area. This source rock produces biogenic gas but can yield oil where sufficiently buried. This is seen particularly in the Rharb Basin where we have either biogenic gas or oil production, depending on the depth of burial of this source rock.

  • 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 %.

  • In most Moroccan Sedimentary basins and for most prospective reservoirs, exist adequate seals. These are:

    -Tertiary marl and shale;Cretaceous shale and marls and, in places, salt and anhydrite;

    -Jurassic shale, anhydrite and in places salt

    -Thick Triassic shale and salt is the most adequate seal for any sub-salt reservoir;

    -Within the Paleozïc succession each shally interval may act as a seal for underlying reservoirs.