Offshore Lebanon: Biogenic and/or Thermogenic Plays? An Answer from 3D Basin Modeling
M. Dubille, Lucien Montadert, J. M. Laigle, and F. Schneider
The Offshore Lebanon is a frontier basin in which hydrocarbon resources are not yet proven. Despite intensive 2D and 3D speculative seismic surveys the geological interpretation remains uncertain by lack of calibration by exploration wells. However recent major discoveries in surrounding countries demonstrated the prospectivity of the whole Levant Basin.
The objective of this study was to assess, for the Ministry of Energy and Water of Lebanon, the hydrocarbon potential of the whole Offshore Lebanon, by evaluating petroleum systems at a regional scale, using the basin modeling methodology.
An integrated interpretation of regional 2D seismic surveys offshore Lebanon provided structural maps and an improvement of the geological knowledge. These data allowed the building of a geological model in 3 dimensions at the scale of the whole offshore Lebanon. The thermogenic source rocks observed in surrounding basins were implemented and tested in the model. An advanced methodology has been developed for identifying which layers could develop a biogenic gas generation potential.
The 3D simulations of hydrocarbon migration lead to the conclusion that the best plays are the Base Miocene-Top Oligocene reservoirs and the Middle Miocene reservoirs if present. At basin scale, the Eocene-Oligocene, and the Miocene are 10 times more prospective than the other play systems (Pliocene and Mesozoic).
The computed HC composition indicated: (1) the gas, mostly biogenic, completely dominates the shallow plays from the Pliocene to the Oligocene; (2) the oil content would increase in the Eocene, and overall in the Cretaceous- Jurassic; (3) then the gas (mostly thermogenic) content would increase again, up to 100% in older plays.
A recent and post study Press announcement of the presence of thermogenic gas in deeper layers below the Lower Miocene-Upper Oligocene discovery at Leviathan (Israel) in the South Levantine Basin, is, to some extent, a validation of the hypothesis that were assumed for this study.
AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013