Petrophysical Properties of Clastic Reservoirs Using NMR Relaxometry and Mercury Injection Data: Bahariya Formation, Egypt

Abstract

The Bahariya Formation is a sedimentary sequence, which was deposited under fluvial to shallow marine conditions at the beginning of the Upper Cretaceous (Cenomanian) transgression in the Western Desert of Egypt. Thirty sandstone core samples, obtained from the Bahariya Formation, are conducted to NMR measurements and the relaxation time T2 = 100 μs and 600 μs were estimated. Application of a model related core-porosity and transverse relaxation time (T2) measured from NMR spectrum; the cementation exponent of Wyllie's type is outlined with high accuracy. Consequently, the water saturation and hydrocarbon saturation will be significantly enhanced. The irreducible water saturation (Swirr) calculated from the mercury injection capillary pressure (MICP) measurements is related to the normalized area under < 4 μs of transverse relaxation time (T2) and a regression model is calculated with a reliable coefficient of correlation permitting calculation of (Swirr) with high accuracy. Lithologic laminations presented in some intervals of the Bahariya Formation have great consequences on both the Mercury injection capillary pressure (MICP) measurements and nuclear magnetic Relaxometry (T2) as well. Thin sections and SEM-micrographs were made for some selected core samples in order to recognize petrography and mineralogy of the Bahariya sandstones. Glauconitic, mica, zircon, rutile and pyrite minerals are predominant in the laminated sandstones intervals.