GEOPHYSICS LETTERS

Ghalib, M. et. al. 33occurrence of organic matter (uranium), which means that the sectionis carbonate build-up (reefs).Secondary porosity was interpreted on the section, due to theporosity calculated by density log is higher than that calculated bysonic log and by shifting of points toward the secondary porosity onM-N cross-plots. The readings, of the density correction curves (Llp),were used to represent that, the secondary porosity is not due tofractures only, but the main part of it is due to vuggy porosity whichindicate that the section is carbonate build-up., The Hammam Faraun sequence was subdivided into main nineelectro litho-zones. These subdivisions represent the vertical andlateral change in the petrographic characters of the sequence (which isa characteristic features to reefs), then the sequence is interpreted ascarbonate build-up (reefs).Nullipore rock in Ras Gharib and Shoab Gharib oil fields can besubdivided, in broad mean, into three main electro-litho groups, basedalso on the response of the Nullipore rock to the log tools, and on theporosity range obtained from the neutron density cross plots. Thebroad grouping of the Nullipore rock in Ras Gharib and Shoab Gharibinto three main electro-litho groups coincides with El Kadi et al(2000) subdivision to the Nullipore rock in Ras Fanar field into threemam groups.The obtained results(by conjunction between the deducted subjects)indicate that the studied section is carbonate build-up (reefs), withsuitable porosity and permeability range to be as potential reservoirs,also the evaluation to the section indicate that it is hydrocarbonbearing in different zones of the section.