Oil and Gas Resources of the North African Trias/Ghadames Petroleum Province

Lunn, Bob¹, Allan F. Driggs², Patrick Thompson², Philip Farfan¹, Patrick Thompson², Francois Gauthier³ (1) Anadarko Petroleum Corporation and Anadarko Algeria Corporation, Houston, TX (2) Anadarko Petroleum Corporation, Houston, TX (3) Worldwide Business Development Group, Houston, TX

Anadarko and its Joint Venture partners, ENI and Maersk, have been active for over 15 years in the Ghadames Basin. This evaluation applied the methodology developed by Arps & Roberts on public domain and company data. It predicts that the Paleozoic sourced – Triassic reservoir petroleum system in the Ghadames Basin has less than 1 billion barrels of oil reserves yet to be discovered. This represents less than twenty-five percent of the potential identified by the USGS's world assessment in 2000. It also predicts that all of those reserves will be distributed in fields with reserves of less than two hundred million barrels. The Paleozoic sourced – Triassic reservoir petroleum system of the Ghadames Basin of North Africa, extends from eastern Algeria, (where its SW extension has been renamed Berkine Basin), southern Tunisia and into western Libya. Oil and gas in Triassic reservoirs have been correlated through the analyses of geochemical markers to Silurian and Devonian mudstones. Migration from the Paleozoic subcrop, uplifted by the Hercynian Orogeny, into overlying Triassic reservoirs was direct and very efficient but; there is also evidence for migration vertically up faults and long distances along Devonian and Silurian sandstone carrier beds. The two source rock intervals had a very similar thermal history, except that the Silurian section is more thermally mature because it is between 1000-2500 meters deeper. During the Hercynian, there was a major hiatus in maturation of the Paleozoic interval and any earlier traps are assumed to have been breached. The next phase of expulsion spanned the Tertiary.