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Micheal D. Cochran1, Lee E. Petersen1
(1) Anadarko Petroleum Corp, Houston, TX

Abstract: The evolution of exploration in the Ghadames Basin, Grand Erg Oriental, Algeria

The Ghadames Basin of eastern Algeria has been one of the world’s most prolific hydrocarbon exploration province through the last decade of the past century. The Algerian portion of this basin, the Berkine Basin of eastern Algeria resulted in discovery of over two billion barrels of recoverable oil. Although exploration focused on Triassic quartz sandstones, flow rates in excess of 3600 BCPD and 38 MMCFGPD have been recorded from Lower Devonian through Carboniferous reservoirs.

Understanding the evolution of Anadarko’s exploration model is instructive in defining remaining hydrocarbon potential of the Berkine Basin as well as possibly indicating a possible path for new exploration in the other basins of N. Africa. The exploration model evolved from a single Silurian hydrocarbon source filling a single primary Lower Devonian reservoir to a dual Silurian and Upper Devonian hydrocarbon source with a complex maturation and trap filling history of multiple reservoirs. Migration-path modeling shifted the primary area of exploration focus from the western up-dip margins where successively older Paleozoic strata are truncated by the Hercynian Unconformity to a more downdip position relative to the present-day basin structural axis. This shift takes advantage of a more complete Paleozoic section and use of regional fault systems as sites of vertical migration and entrapment. Employment of geophysical data as the primary tool for definition of prospects evolved from reprocessing of existing seismic to acquisition of a new grid of 120 fold seismic.

Existence of high quality source rocks, a Liassic evaporite “super seal”, favorable tectonic history with respect to hydrocarbon generation and expulsion, and high quality hydrocarbon migration carrier beds leads us to conclude primary risk in successful exploration for additional reserves involves seismic imaging of reservoirs and traps. The evolution of the exploration model indicates that creative thinking and application of leading edge technology can still yield outstanding success.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana