Taoudeni Basin Overview
Geology and Prospectivity
The Taoudeni Basin underlies eastern Mauritania and Western Mali and is one of the largest and most under-explored Early Palaeozoic Basins in Africa. The Taoudeni Basin is one of the major structural units of the West African Craton, covering in excess of 1 million sq km. Sediment thicknesses exceed 5 km and may reach 10 km in places.
The sediments are predominantly Precambrian to Carboniferous in age with only thin Mesozoic or younger rocks present. The basin is interpreted to contain good quality source rocks of Silurian and Precambrian age, as well as a range of potential reservoir and seal rocks. The presence of large traps is suggested by the available geophysical data although more seismic is required to define potential drilling targets.
The Silurian source rocks are believed to be equivalent to the organic rich Tanezzuft Shale present in the prolific oil and gas producing basins of Algeria, immediately to the north. Precambrian source rocks are proven oil and gas sources in a number of basins around the world, including the Huqf Basin of Oman and West Siberia Basin of Russia. Anecdotally, outcrops of these black Pre-cambrian shales on the northern rim of the Taoudeni Basin are gathered and burned for fuel by local inhabitants.
Four wells have been drilled in the Taoudeni Basin to date, two in Mauritania in the early 1970’s and two in Mali in the mid 1980’s. All of these wells had oil or gas shows while one (Abolag-1), drilled in 1974 by Texaco, flowed 480,000 cubic feet per day of gas during drill stem testing from Precambrian limestones. These wells were drilled on a sparse seismic grid with line spaced between 10 and 50 km.
Baraka’s acreage holdings extend over the main hydrocarbon generating kitchen and surrounding area and therefore cover the more prospective portion of the Taoudeni Basin. The Taoudeni Basin extends into southern Algeria where recent exploration permits have been awarded as a consequence of Baraka’s activity in the basin.
The Taoudeni Basin shows geological similarities to a number of productive North African basins, the most pertinent being the Reggane Basin of southern Algeria. The Taoudeni and Reggane Basins shared stratigraphy from the Precambrian to Late Paleozoic – a long interval covering the deposition of proven source, reservoir and seal rocks. The basins were only separated by the Hercynian Orogeny during the Late Paleozoic. The Reggane Basin has been explored by companies such as Eni and Sonatrach with some 16 tcf of gas and 750 mmbbls of oil discovered to date.
There are several major risks to petroleum exploration in the Taoudeni Basin. There is a lack of knowledge on the volume and distribution of intrusive rocks in the basin, and the detailed structural architecture of the basin itself is poorly understood. These deficiencies have been targeted by Baraka’s past and ongoing work programmes. It should also be noted that the Taoudeni’s geological history is also relatively poorly understood due to the limited amount of previous exploration activity, the low density of basic reconaissance data and the paucity of outcrops (except on the basin margins several hundred km away).
Although Baraka believes the Taoudeni Basin is highly prospective for hydrocarbons, the remote location, hostile conditions and expensive operating environment combine to make this an expensive and slow area to evaluate.