Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Geology

The study Arshad area in Sirt Basin, Libya being bounded by major NW-SE fault rifting systems and include gas reservoir in the north and oil in the south. The Upper Cretaceous stratigraphic units include Arshad, Sirte and Kalash formations that rest unconformabaly on the Upper Paleozoic Gargaf sandstone being separated by the Hercynian events. The present study focuses on the silici-clastic hydrocarbon-bearing reservoirs (i.e. Arshad sandstones), in addition to the main source and seal rocks of the Sirte Formation. The Arshad Sandstone is interpreted to be derived from the older Paleozoic sandstones, being proved by sedimentational interpretation of conventional core analysis data. Meanwhile Sirte Shale was originated by a major flooding event during the Campanian sea level rise that was focused for source rock evaluation. Cyclolog® applications including PEFA- and INPEFA patterns where major truncations and inflection events could be predicted and correlated along the study area. Based on the progadation, and retrogradation patterns of the Upper Cretaceous sequences, four major sedimentary cycles could be distinguished bounded by five sequence boundaries (SB Types-1 and -2). Each cycle was deposited during the progradation phase passing to the retrogradation IPEFA patterns, reflecting the rate of sediment accumulation vs. tectonics. These are correlated with the Global Mesozoic cycle charts. The sedimentary cycles were subdivided into seven 2nd order cycles UZA-3 (3.4 and 3.5), UZA-4 (4.1-4.5) commonly bounded by stratigraphic inflection of PEFA peaks and INPEFA trends. Sedimentary cycle no

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