- Copyright © 2000 Society of Exploration Geophysicists
Predicting sand distribution and reservoir presence is a major exploration risk in the Nile Delta offshore Egypt. However, integrating state-of-the-art technologies including 3-D seismic reflection surveys, seismic attributes, amplitude extractions, and coherency techniques can reduce this risk through recognition and more accurate mapping of submarine valleys and channel complexes. In addition, identification of sediment input points and pathways may result in more accurate interpretations of sand distribution patterns.
Seismic profiles from the area of interest indicate that Upper Miocene (Messinian) evaporites created a series of bright reflectors that are overlain by a Lower Pliocene transgressive sequence which, based on well control and seismic character, appears relatively sand-rich. The shale-prone Middle Pliocene section is relatively dim, with weak and discontinuous reflections and some obvious erosional surfaces. The Upper Pliocene and Pleistocene sections are complex, with abundant erosional and slump surfaces. They are seismically brighter, and well control indicates that they are sandy.
Within the Lower Pliocene interval, strike-oriented seismic profiles suggest that channels and valleys are present. Seismic character of the valley/channel fills is complex, with multiple incised surfaces, aggradational fill, and evidence of lateral accretion on some sections. Coherency horizon slices show the Upper Miocene-Lower Pliocene channel systems are confined to a single valley that is broad, relatively deep, and generally sinuous. Higher in the stratigraphic section, single valleys divide into multiple channel courses which are narrower, shallower, and less sinuous. These changes are interpreted to reflect the transition from more proximal to more distal submarine channel facies as Nile Delta system tracts backstepped during the Late Miocene-Early Pliocene transgression.
These submarine, delta-front channel complexes appear in plan view to be very similar to fluvial channels. Assuming the channel patterns are the result of similar physical processes in both depositional settings, submarine channels should be subject to the same type …