الفهرس | Only 14 pages are availabe for public view |
Abstract The objective of the present logging study is the lithofacies analysis of the Miocene clastic rock units in Ras Ghara area, Gulf of Suez, Egypt. The area of study is located in the southern part of the Gulf of Suez, where the western dip regime is dominant. Such an analysis was carried out on two formations (Kareem and Rudeis) selected in the Miocene sequence. Ten wells (Sinai-1, Sinai-2, Sinai-3, Sinai-4, GM-Aief-1, GM-Dal-1, GM-Dal-2, GM Geem-1, GM-Haa-1 and GM-4) were utilized for accomplishing this assessment. Such a study is performed using the different types of open-hole well logs, such as : Neutron, Density, Sonic, Gamma Ray, Natural Gamma-Ray Spectroscopy, Litho-Density Tool and Resistivity for the determination of the included petrophysical parameters. Such a work is conducted through several stages, started by reviewing the geologic setting of the study area through the previous geologic works and literatures, to shed lights on the subsurface stratigraphy, paleogeography, structures, tectonics, geologic history and previous exploration activities. from these wells, the study of the mineralogic composition of these rock units is needed. This is done through the crossplots technique to detect the rocks forming minerals such as silicates (quartz and potash feldspars), clay minerals (montmorillonite, illite, kaolinite and glauconite), carbonates (calcite and dolomite) and evaporites (anhydrite). For Kareem Formation, the following minerals are indicated : quartz, calcite, montmorillonite, illite, Kfeldspar and anhydrite. For Rudeis Formation they are : quartz, calcite, dolomite, illite, montmorillonite, K-feldspar, kaolinite and glauconite. These mineral constituents are represented, zonewise, in the form of litho-porosity crossplots to show their vertical distribution within each well. The spatial distribution of the rocks forming minerals are represented by the iso-parametric maps to illustrate their lateral changes for both Kareem and Rudeis Formations across the study area. The use of wireline logging tools has been widely practiced to evaluate the matrix constituents, beside the pore volume through sonic, density and neutron tools. The methodology is easily coded as graphical techniques (M-N crossplot and Ternary diagram), in which whose outputs are mineralogic and/or porosity contents. A modified technique has been proposed for judging and controlling the lithofacies constituents, that deduced from the porosity logs (<pN, Pb and ~T). Three lithologic components have been deduced. These are residual chert with carbonate, carbonate with residual chert and shaly carbonate. A number of lithofacies maps were constructed for the Kareem and Rudeis Formations. The more realistic picture deduced for the lithofacies conditions of the evaluated rock units in the considered area shows their wide range of depositional environments. Accordingly, the Kareem Formation reveals more continental affinity in the form of fluvio-marine to shallow marine conditions, while the Rudeis Formation reflects more maritime affinity in the form of shallow to deep marine conditions, with the heavier hydrothermal flux and more cyclic sedimentation for the latter rock unit. Moreover, the maximum average and minimum values for the effective porosity, water saturation, irreducible water saturation, saturated hydrocarbons and permeability were defined to delineate the effect of the implied minerals on the reservoir quality. Regarding the reservoir performance of the studied formations, the Kareem Formation reflects a poor to fair reservoir quality, because its mineral association (quartz, K-feldspar, montmorillonite, illite, calcite and anhydrite) plays a prominent part in the definition of the reservoir capabilities. In Rudeis Formation, the mineral content (quartz, K-feldspar, montmorillonite, illite, kaolinite, glauconite, calcite and dolomite) reflects fair to good reservoir quality. |