GEOPHYSICAL STUDIES IN SOUTH SIWA AREA, WESTERN DESERT, EGYPT UTILIZING SEISMIC INTERPRETATIONS AND WELL LOGGING ANALYSIS

Abstract

The study area lies in what is known as '' The Great Sand Sea'' and the terrain is covered in its majority with thick sand dunes ( the largest of the dune-covered areas in Egypt) varying in height and running in NNW- SSE direction. The regional structural development of the region throughout the geological history was mostly controlled by the Paleozoic tectonic cycles and later by the Jurassic events associated with the opening of the Neo-Tethys Ocean. South Siwa area is a relatively small intracratonic depression developed farther south in the southern parts of Western Desert. It was developed during the Paleozoic time and was probably part of a larger Paleozoic basin combining the Kufra, Dakhla and Foram basins. The present structure framework of the basin was further developed during the Jurassic tectonics related to the opening of the Tethyan Ocean. It accommodates more than 4500 meters of Paleozoic, Mesozoic and Tertiary strata. The main objective of this study is to map structural configuration affecting on the South Siwa area depending on seismic, dipmeter, and gravity data. 2D seismic interpretation was carried out on the study area to build a regional geological view about it. But as a result of the surface topography, most of the seismic lines were shot in NNW-SSE direction parallel to the longitudinal sand dunes with large line space. In order to overcome this problem, the available geological and geophysical data will be analyzed to give integrated and reliable structural picture for the study area. Other objectives are: firstly; review the exploration history and activity in the study area to outline the regional geological setup of the area. Secondly; understand the tectonic and structural trends of the area and delineate the subsurface target horizons in the study area. Thirdly; evaluate the hydrocarbon potentialities of the reservoirs in the study area. Chapter one discusses the location of the study area, aim and objective of the study, the available data, methodology and technique used, and the exploration history and activities done in the study area. Chapter two deals with four main items, firstly; the subsurface stratigraphy of the Southern Western Desert, with special reference to the area under investigation, secondly; the structure pattern result of the tectonism effect on the study area, thirdly; the tectonism effect on the study area and lastly; the arrangement of various stratigraphic, structural and tectonic framework in a compiled form to reflect the geologic history of the study area. Chapter threediscusses seismic data interpretation of the available seismic data in the study area. A set of time and structural contour maps generated from the seismic data on top Upper Cretaceous (Cenomanian), Jurassic, Upper Carboniferous, Lower Carboniferous, Upper Devonian, Lower Devonian, and Cambro-Ordovician ages, were constructed using Petrel 2009 Seismic Interpretation Software and were useful in reflecting the prevalence of structural tectonic trends. These trends of local structures are believed to be produced as a result of comparable systems of regional tectonic deformations affecting the surrounding regions. The trends of the faults are: NNW-SSE, NW-SE, E-W, WNW-ESE, NE-SW, and ENE-WSW directions. But as a result of the surface topography, most of the seismic lines were shot in NNW-SSE direction parallel to the longitudinal sand dunes. So, the obtained structural maps show poor image about structures in the subsurface. Structural image was achieved through analysis of dipmeter