Systematic petrophysical studies were carried out on some calcareous sandstone samples selected from Gebel Hadahid area, Wadi Feiran, south west Sinai,. The studied rock samples are belonging to the Lower Miocene (Rudeis Formation, 338.8 m) which conformably overlies the Nukhul Formation and unconformably underlies Quaternary gravels and sands. The Lower Miocene rocks of the studied area are composed mainly of sandstones intercalated with shale beds and few sandy limestone intercalations at the base. The studied samples were deposited in a fluviatile and mixed aeolian-fluviatile environment. The storage capacity of the studied rocks was diminished by cementation, mostly by calcite cementation, and rarely by hematite or silica cement.
The collected samples were subjected to comprehensive systematic petrophysical investigations including measuring of the bulk density, the porosity, permeability, irreducible water saturation, electric tortuosity of channels, apparent electric resistivity of samples saturated with NaCl solution of three successive concentrations (6, 60, and 120 kppm), and the true electric resistivity. The petrophysical analysis enabled distinguishing three petrophysical facies. The lower and middle facies (lower and middle parts of Rudeis Formation) have good storage capacity properties due to their high porosity and permeability values, whereas the third facies (topmost parts of Rudeis Formation) has fair storage capacity properties.