The Taoudeni Basin is a vast sedimentary basin of 1,500,000 square km, a third of which is located in Mauritania, dating from the end of the Precambrian to the Paleozoic. It is a large intracratonic basin that appears to have been formed in response to the Pan-African Orogeny. The basin started in the Infracambrian and continued to develop during the Paleozoic until the Carboniferous.
The Taoudeni Basin has witnessed two important exploration periods:
In the early 1970s, Texaco and Agip have each allocated a block, and carried out 2D seismic surveys and then respectively dug wells Abolag-1 and Ouasa-1. The Abolag-1 well crossed two reservoir levels, one of which (middle Infracambrian stromatolite limestone) produced the equivalent of 480,280 cf per day of gas during a two hours’ DST (Drill Stem Test).
The second period began in 2004, when exploration resumed with Total, Repsol, Sipex and SMH. It has yielded greater 2D seismic coverage and the drilling of the Atil-1 (Ta8-1), Ta7-1 and Ouguiya-1 wells which have revealed some gas shows and low yields.
Potential of the Taoudeni Basin
Two petroleum systems have been identified:
Paleozoic petroleum system, related to good quality Silurian and Devonian source rocks and Ordovician reservoirs.
Neo-Proterozoic petroleum system, related to source rocks of interstratified Infracambrian black shales and reservoirs of fractured limestone with stromatolites and sandstones.
Seismic coverage in the basin: more than 15,000 km of 2D.
Exploration wells: Abolag-1; Ouasa-1; Atil-1 (Ta8-1); Ta7-1 and Ouguiya-1.
The Coastal Basin
History of exploration
Exploration started in the Coastal Basin as early as 1960s. Since then, nearly 45 exploitation wells have been drilled, out of a total of 78 wells, with 11 discoveries. The 3D seismic coverage is dense (covering more than 100,000 square km), while the 2D one is 100,000 km.
The discovery of Chinguetti oil field in 2001 was the first in the MSGCB area and opened up the Tertiary petroleum system in the basin. This discovery was followed by a serie of discoveries during the same decade, in particular Banda and Walata (formerly Thiof).
The other major event was the large scale gas discovery of GTA in 2015, block C8, which opened up the deeper Cretaceous petroleum systems. This important gas discovery was followed by BirAllah in the same year, following the drilling of Marsouin-1 in block C8. This led to revived interests in the basin, as seen with the presence of many major companies such as BP, Kosmos Energy, Total Energies, Shell and Capricorn.
Seismic coverage in the basin: more than 100,000 square km of 3D and 100,000 km of 2D.
Wells: 82 wells, including 4 wells drilled in 2022 in GTA’s development Phase 1.
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