--> --> Abstract: Multiple Reflections and Head Waves in Gulf of Suez, by S. N. Domenico; #90963 (1978).
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Abstract: Multiple Reflections and Previous HitHeadNext Hit Previous HitWavesNext Hit in Gulf of Suez

S. N. Domenico

Inferior reflection quality in the Gulf of Suez at the objective depth interval is attributable in part to surficial multiple reflections. An excellent example of the latter is observed on a typical seismic line from the northern Gulf of Suez. An increase in prominence of the multiple reflections appears associated with decreasing depth to a dipping high-velocity Previous HitlayerNext Hit below the water bottom.

Inversion of a second-order polynomial time-distance function, fitted to the observed refraction onset time and associated distance values, gives the velocity-depth function for sediments between the water bottom and a high-velocity Previous HitlayerNext Hit. Velocities thus determined increase nonlinearly with depth from a value near water velocity at the water bottom. Depths to the high-velocity Previous HitlayerNext Hit are obtained from the associated Previous HitheadNext Hit-wave linear time and distance function and by ray tracing in the overlying sediments.

As the high-velocity Previous HitlayerNext Hit approaches the water bottom from subwater depths exceeding 0.6 km to a depth of 56 m, intensity of the multiple reflections increases to the extent of completely dominating individual records to a time of at least 3 seconds. The estimated plane-wave normal-incident reflection coefficient at the top of the high-velocity Previous HitlayerNext Hit increases with decreasing depth to this Previous HitlayerNext Hit, approaching 0.5 at the shallowest depth. This substantial reflection coefficient further substantiates the existence of multiple reflections between the high-velocity and water Previous HitlayerNext Hit. However, existence of water-Previous HitlayerNext Hit multiples cannot be ruled out. The estimated water-bottom reflection coefficient is approximately 0.3, a substantial value. Multiple reflections of considerably less intensity re apparent where the high-velocity Previous HitlayerNext Hit is deepest, and it is probable that such are water-Previous HitlayerNext Hit multiple reflections. Unfortunately, water-Previous HitlayerNext Hit multiple reflections and multiple reflections between the water surface and high-velocity Previous HitlayerTop cannot be separated by their coincidence with time-distance (normal moveout) curves, the configuration of each visibly matching the curves equally well.

AAPG Search and Discovery Article #90963©1978 AAPG/SEG/SEPM Pacific Section Meeting, Sacramento, California