Fadi H. Nader

Petroleum prospects of Lebanon: some remarks from sedimentological and diagenetic studies of Jurassic carbonates

Abstract Only seven exploration wells have been drilled in Lebanon to date, failing to encounter oil or gas in commercial quantities and to penetrate into unexposed pre-Jurassic reservoirs. This paper shows that the sedimentological and diagenetic characteristics of the major Lebanese Jurassic carbonate rock unit (the Kesrouane Formation; thickness >1000 m) negate Jurassic hydrocarbon prospectivity in northern Mount Lebanon. The Jurassic platform in this region was subjected to a first emergence and invasion by meteoric waters in the Late Jurassic, causing a pervasive cementation. A second phase of uplift and meteoric flushing occurred in the Cenozoic. Thus, only the areas located far from the Jurassic and post-Cretaceous phreatic realms (e.g. offshore Tripoli, NW Lebanon) may have been less affected by meteoric diagenesis and still provide promising prospects. A 1993 seismic survey, offshore Tripoli, confirmed the presence of Late Triassic evaporites in northern Lebanon. This also adds confidence to the results of the Nahr Ibrahim electrical survey, which earlier suggested the presence of these evaporites in the subsurface of central Lebanon. The pre-Jurassic sequence, hence, is sealed and protected from the meteoric invasion observed in the overlying Jurassic rocks. Accordingly, the Qartaba horst structure (central-northern Lebanon) would be equally, if not more, attractive for a pre-Jurassic play.