Identifying Organic-Rich Intervals Sourcing the Pliocene-Quaternary Yafo Petroleum System Biogenic Gas in the Levant Basin

Abstract

Summary Analysis of high-resolution seismic reflection data reveals fluid-flow elements within the buried intra- to post-Messinian salt features and the overlying Plio-Quaternary unit of the Levant Basin. Additionally, natural methane seepages through seafloor sediments have been identified across the Nile deep-sea fan, Levant Basin, Eratosthenes Seamount, and other localities in the Eastern Mediterranean. Lastly, gas was discovered in sandstone of latest Miocene-Early Pliocene age at a depth of 1130 m and in Pleistocene calcareous sandstone units at depths of 300–450 m (the Noa-1, Mari-B, Nir, Or and Gaza Marine gas fields). The reservoir rock is the Yafo Sand Member, which is found at the base of the Pliocene Yafo Fm overlaying Messinian evaporites. However, the source rock of these biogenic gas discoveries is still unknown. We integrate geophysical and sedimentological/geochemical analysis of offshore well samples, with the intent of identifying these source rocks, and have identified three potential organic-rich (1–4 % TOC) source rocks, composed of gas-prone kerogen type III organic matter: a ∼200 m interval underlying the thick (1.8 km) MSC salt; discreet diatomite layers with a cumulative thickness of 25–40 m interbedded within the salt; a 20 m interval about 25 m above the top of the MSC unit.