The Impact of Seismic Reflection and Well Logging Interpretation In clarifying the near-surface Velocity Variations ofEl-FayumArea, Western Desert, Egypt

Abstract

El-Fayum field area is located at the eastern part of the North Western Desert of Egypt. The area of study lies at the northern part of El-Fayum field and started to re-exploration in 1960’s with Gindi-1x well then, more than 10 wells were drilled by several companies, since that date till the present time, most of them were reported as P&A dry holes. In2004, El-Fayum Field, including the area of study, awarded to Merlon El-Fayum International Oil Company, the company tried success to find oil over El-Fayum concession, where a dry well was drilled in the area of study, regardless the area is considered unexplored. The main purpose of the present study is to arrive at a solution for the famous un-solved problem concerning the near-surface velocity variations, which create low and/or high velocity anomalies. The surface and near-surface layers act as filter or controlling factor for passing the seismic reflection wave into subsurface layers, with loose sediment (low velocity of the weathered layer) or igneous rock(high velocity of the Basaltic extrusion), resultingwave velocities varying abnormally and continuously with depth, and miss-leading the exploration activity in the area. To achieve this purpose, the thesis program started with collecting the geological and geophysical data, studying the geologic setting of the concerned area to evaluate the structural elements, critiquing the stratigraphic column to evaluate the lithologic contents and clarifying the tectonic events standing behind the synthesis structural and stratigraphic regimes. Seismic interpretation was done for 2D PSTM data to clarify the structural elements trends and configuration, velocity regime analysis to show the distribution of low and high velocity anomalies and their effecton

ii the general velocity regime, seismic stratigraphic analysis to illustrate the thickness variations and lithofacies contents of the concerned rock units and their depositional environments across the area of study, combined with the available well analysis. Integrating all the inferred results to find a velocity model for the complex near-surface low and high velocity anomalies.