Unlocking the Nile Delta subsurface via advanced processing and imaging

Abstract

The subsurface of the Nile Delta is infamous for challenges that are caused by a variety of geologic features that need to be resolved to unlock the full potential of the basin. The primary cause for many of the issues is the Messinian interval. This is a well-studied regional salt body with significant variation in composition, ranging from mobile shales to sand bodies over contaminated salt to anhydrite. The layer locally shows a hard top and base, which sets up mode conversions and complex multiples. The Messinian is also highly variable in terms of its geometry, thickness, faulting, and rugosity, which results in significant scattering of the seismic wavefield. The problem is further complicated by the presence of mud volcanoes that are scattered throughout the basin. Some of the mud volcanoes are currently active, and others are buried beneath more recent deposits. Free gas is often associated with these structures, and a high degree of lateral and vertical rock property variation is present, leading to complexities in seismic velocity and attenuation. The water depth varies considerably within the basin. Some producing assets exist that straddle the coastline, while others are located in water depths in excess of 1000 m. The transition is not simple due to erosional features on the seabed, leading to complex free-surface multiples. While many discoveries and developments have already been made in the post-Messinian, prospectivity in the basin is now located in the pre-Messinian, with targets ranging in depth from 2 to 10 km. When all of these features are combined, it results in a truly complex geophysical challenge.