Nile Delta Gas Origin and Biogenic Gas Potential
Sherif Hemdan and Jonathan McQuilken
Many TCF of gas have been discovered in the Nile Delta during the last 40 years, from different stratigraphic levels, ranging from the Oligocene to the Pliocene. Gas isotope data and fluid analyses have been interpreted to indicate their origin. This reveals that most of the Pliocene gases are of mixed biogenic / thermogenic origin. The thermogenic gas contribution generally increases with depth, depending on the presence of deep seated faults to act as conduits for gas migration. Pre-Pliocene gases are mostly thermogenic in origin. The level of interpreted source rock maturity for the gas is 0.8-1.0 Ro. This corresponds to top Oligocene maturity levels. Some gases indicate higher maturity source rocks (Pre-Tertiary sequences). Basin Modelling shows greater maturity and wider areal distribution for pre-Tertiary source rocks relative to the top Oligocene. Biogenic gas modelling indicates that the Lower Pliocene and the lower interval of the Upper Pliocene have the highest potential to generate and trap biogenic gas particularly in the thickest Plio-Pleistocene sequences. Modelling suggests the Miocene sequences have generated even higher volumes of biogenic gas than the Plio-Pleistocene sequences. However, these have not been preserved due to lower rates of sediment accumulation.
AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013