Offshore Lebanon Research Articles

Possible seismic hydrocarbon indicators in offshore Cyprus and Lebanon

ABSTRACT A multi-client 2-D seismic survey, consisting of 6,770 line-kilometer of 2-D data, was acquired by Norway’s PGS Geophysical offshore Cyprus in 2006. It was followed in 2006 and 2007 by the acquisition of two 3-D surveys, located offshore Lebanon (1,500 square kilometers), and offshore Lebanon and Cyprus (1,300 square kilometers). Further, in 2008 an additional 2-D survey was acquired offshore Cyprus to fill in the existing 2006 seismic 2-D grid. The 2008 2-D survey consist of 6,500 line-kilometer and was acquired with the PGS dual sensor GeoStreamer® technology (The 2008 2D data is still being processed so no GeoStreamer® examples are shown in this article). Since 2007, some of the deep-water areas (1,500–2,000 meters deep) offshore Cyprus have been offered for exploration and producing bid licenses by the government, while the Lebanese government is in the stage of preparing its offshore region for exploration and licensing. In this paper, several representative seismic lines are shown to illustrate the quality of the seismic data over this large region. The data shows that a Pliocene to Recent succession overlies a thick Upper Miocene evaporite section, known as the Messinian Salt. The blanketing salt-dominated interval is up to one kilometer thick and provides a regional seal over the area; although some faults are known to penetrate the salt and may allow seepage to occur. The pre-Messinian Salt section is highly structured, with both horsts-and-grabens as well as large folds. In particular, several examples of seismic reflections are presented, which are interpreted as possible Direct Hydrocarbon Indicators (DHI). Some four-way structural closures are highly prospective as they are characterized by multiple DHIs; for example, a bright spot at the base of the Messinian Salt overlying a flat spot. Other examples consist of phase changes, dim spots, velocity pull-downs, low-frequency shadow zones and gas chimneys. Also shown are how some of these interpreted DHIs can be characterized in the 3-D surveys. The 3-D example illustrate a correlation between pre-Messinian four-way structural closure and the root-mean square amplitude of the base Messinian Salt reflection.

Hydrocarbon plays and prospectivity of the Levantine Basin, offshore Lebanon and Syria from modern seismic data

ABSTRACT The Levantine Basin is located in the easternmost region of the Mediterranean Sea between Cyprus and the Nile Delta marine cone in Egypt. Based on an analysis of more than 20,000 line-km of 2-D seismic data, the basin appears to contain up to 10,000 metres of Mesozoic and Cenozoic rocks above a rifted Triassic-Lower Jurassic terrain. Although many hydrocarbon discoveries have been made in the Nile Delta and the near-offshore areas in the southeastern Mediterranean Sea, no exploration wells have been drilled in its deep offshore or anywhere offshore Lebanon, Syria and Cyprus. Widespread occurrence of oil seeps (over 200) that closely correlate to hydrocarbon indication on seismic (e.g. bright spots and gas chimneys associated with possible migration pathways) suggest that the undrilled parts of the Levantine Basin can be prospective. Thirteen potential exploration plays are identified in this study and illustrated with seismic examples. The plays range in age from the Triassic to the Neogene-Pliocene.

Observations on geomorphology, transportation and distribution of sediments in western Lebanon and its continental shelf and slope regions

The geomorphology, drainage systems and predominant lithologies of western Lebanon are briefly described as a background for sediment transportation into the eastern Mediterranean. Fragmentary past and current bathymetric work over offshore Lebanon is reviewed and a simplified compilation bathymetric map correlating and interpreting the different survey results is presented. It reveals a narrow continental shelf about 3 km in width with two wider areas in the north and south; the shelf break occurs generally at about 100 m depth. Submarine valleys are common, most of which are seaward continuations of important land valleys but some prolong land-fault trends. Many continue down the continental slope, dividing into “distributaries”. Hydrological data indicate that over 2,525 × 10 6 m 3 of surface-water runoff annually discharges into the sea through the perennial streams of western Lebanon. A high proportion of the country exposes carbonate rocks but a number of the stream basins drain appreciable areas of soft clastics; preliminary work suggests that these contribute appreciable loads into the Mediterranean. Overall marine net sediment transport is northwards by the longshore current and predominant WSW-ENE directed waves, but investigations in progress indicate that the submarine valleys provide avenues for cross-shelf and down-slope movement for much sediment.