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Abstract The Gulf of Suez is considered as one of the most productive provinces in Egypt, which contains a lot of reservoirs that ranges in age from Pre-Cambrian to Quaternary and the present study focus on the petroleum potentiality of Cretaceous reservoirs in the Central Gulf of Suez. The area of study extended in latitude from 22° 34’ 41’’ N to 22° 34’ 48’’ N and in longitude from 25° 01’ 39’’ E to 25° 01’ 48’’ E. The present work is denoted for Cretaceous Nubia Formation in October Oil Field, Central part of Gulf of Suez, Egypt to give the tectonic and stratigraphic framework description via Seismic study to clarify structural and stratigraphic complexity using seismic pattern, seismic attributes, seismic maps, cross section analysis in which to help in distribution of extra development and production wells that can aim the productivity and profitability with integration of well log analysis and subsurface geology of the study area estimating different petrophysical parameters and hydrocarbon potentialities of Nubia Formation through four wells (OCT-A1ST1, OCT-A2B, OCT-B2, OCT-H3). The available data include 2D 20 Seismic lines, log data includes the Shale volume tool(Gamma Ray), Resistivity tools(shallow and deep devices), porosity tools(Sonic, Density and Neutron logs), Mechanical tool(Caliper log) plus wells X, Y, Stratigraphic sequences of Formation Evaluation logs, Directional surveys. Nubia Sandstone is considered as the zone of interest and the main producing rock unit in Paleozoic-Cretaceous age. Its average thickness in main area is 2300 feet and is classified as medium-grained, moderately to well sorted quartz arenites. Quartz and kaolinite are the main authigenic cements, with dolomite and calcite locally present, particularly in the Transitional Nubia unit. medium-grained, moderately to well sorted quartz, improvement up-section in textural, compositional maturity and increase in lateral continuity of bedding represents continental fluvial. Sudr formation of Cretaceous age supply Nubia sandstone as source rock that expect started generating oil in Miocene. Nubia reservoirs are top sealed by overlying Cretaceous shales of the Raha Formation and sealed laterally by downthrown Miocene shales of the Lower Rudeis Formation. The ultimate seal is provided by the overlying Miocene evaporites of the South Gharib and Zeit formations. The seismic studies of the area including structural and stratigraphic complexity analysis with structural maps, cross sections, seismic patterns and attributes show that Nubia Sandstone reservoir is fault-bounded to the SW and south, and is dip with fault extends up into the post-Zeit sediments, that mean trap was probably not established until the Pliocene. The well log analysis of available data that including distribution & isometric maps (shale volume, porosity, permeability, hydrocarbon maps) show that the Nubia Sandstone temperature around ± 230°F and is considered as a clean reservoir in most of wells (average volume of shale 6-7%) with average effective porosity up to 15-17%. The formation water resistivity at reservoir temperature ranges from 0.02-0.03 ohm.m. The effective water saturation ranges from 23-65% and hydrocarbon saturation from 35-97%. The permeability ranges from 50-392 mD. |