MINERAL CONSTITUENTS AND COMPOSITION OF ABU MADI FORMATION IN EL QARA FIELD, NILE DELTA AREA, EGYPT | ||||
| Journal of Egyptian Geophysical Society | ||||
| Volume 9, Issue 1, 2011, Page 75-85 PDF (1.21 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jegs.2011.384439 | ||||
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| Authors | ||||
| A.Z. Nouh; M.F. Abu-Hashish | ||||
| The British University in Egypt, El Sherouk City, Cairo, Egypt Geology Department, Faculty of Science, Menoufiya University, Egypt | ||||
| Abstract | ||||
| The available open-hole well log data of the studied Nile Delta area are subjected to computer processed analysis to determine the mineralogic composition of the Abu Madi Formation. This analysis started by the correction of the density and neutron readings for the environmental errors, then presenting the available log data in the form of crossplots to facilitate the qualitative interpretation needed for defining the mineralogic composition for the studied rock unit; Abu Madi Formation. The mathematical equations, describing the mineral constituents suggested in each model, are established to compute the mineralogic composition and the total porosity for the studied unit. The resulted mineralogic constituents and porosity were represented in the form of histograms to show the different mineralogic constituents of this formation. Moreover, the lithologic-geologic model of Abu Madi Formation, shows that, the presence of illite and montmorillonite is revealed to a near-by source from the site of deposition of intertidal environment. The existence of quartz in considerable proportion with high radioactivity reflects the detrital nature and the high chemical maturity. The occurrence of kaolinite reflects the high uranium content, which is produced from the concentration of the uranium rich fluids that migrated through fault planes. Kaolinite favors continental to near-shore (fluvio-lacustrine) environments through the deposition. The occurrence of potash feldspars is attributed to the denudation of the underlying acidic basement complex. It was found that the porosity data of the selected samples of the Abu Madi Formations at El Qara Field indicated that the porosity varies from 0.7 % to 29.10 % with a mean value of 17.8 %, while the analyses of the permeability of these samples varies from 0.02 mD and 1369 mD, with a mean value of 123.8 mD. In addition, the water saturation values of the Late Miocene rocks, at El Qara Field, varies from 16.1 % and 96.4 %, with a mean value of 63.1 %. To investigate the mineralogical composition of the studied lithofacies XRD analysis was conducted to the whole samples side by side with the microscopic investigations. It was found that the major constituent of the studied sandstones is the quartz with different forms (monocrystalline and polycrystalline), with little amount of feldspar minerals and rock fragments. The studied lithofacies of the Abu Madi Formation in the study area is mostly quartz arenite, with about 95 % quartz.The Abu Madi Formation (lithologically) can be divided into three sand levels or units separated by thick silty mud bed. These are designated as sand level I, II and III. The present study concentrates on Level III since it comprises most of the gas accumulation in the study area. | ||||
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