Using polygonal layer-bound normal faults as tools to delimit clastic reservoirs in the Levant Basin offshore Lebanon

The Levant Basin offshore Lebanon contains an array of layer-bound normal faults in the Oligo-Miocene units. The faults are believed to have nucleated in soft-grained sediments similar to polygonal fault systems worldwide, and as a result are influenced by lithological heterogeneities in the host rock unit. We used 3D seismic data and amplitude extraction from offshore Lebanon to map deepwater channels and fan lobes, and demonstrate that the distribution, geometry and growth of the layer-bound normal faults is affected by these sedimentary bodies which are acting as barriers to fault propagation. Three fault types are identified, differentiated by their growth models and overall geometry. Type I faults in the deep basin indicate that a competent unit is present along the base Miocene and is affecting their growth. Type II and III faults in the Lattakia Ridge and the margin respectively are smaller due to restriction by Upper Miocene and Lower Oligocene basin floor fans. Based on their seismic expression and on analogy with other basins containing similar faults, we deduce that the units causing restriction consist of sand rich intervals. Therefore, reservoirs offshore Lebanon are probably along the base Miocene in the deep basin, while in the Lattakia Ridge and the Levant margin, reservoirs are in Upper Miocene and in Lower Oligocene units. This study provides an additional evidence that layer-bound, or polygonal faults, can have practical industrial application during exploration of hydrocarbons, even in the absence of well data.