Publication Date:
2009-06-01
Description:
Several methods have been developed to characterize the pore spaces in sandstone reservoirs using data on the pore-throat-size distribution obtained from mercury injection tests. The Winland equation, the threshold pressure, the displacement pressure, and Pittman's equation are mostly used for this purpose to delineate the stratigraphic traps and seals. This study examines the reliability of these methods applied to the highly permeable Nubia sandstones in their type section in southern Egypt. These sandstones are composed mainly of siliceous sandstones and constitute the main Paleozoic–Cretaceous aquifers and reservoirs in Egypt. Routine core analysis and mercury injection tests were conducted to delineate the pore network characteristics for these rocks. The relationships between helium porosity and the uncorrected air permeability from the routine core analysis, and the various parameters derived from mercury injection–capillary pressure curves were established using multiple regressions. This study indicates the high reliability of the displacement pressure at 10% mercury saturation and also reveals the apex of Pittman's hyperbole at 45% mercury saturation as a complexity apex at which the pore network becomes highly chaotic. Despite the great benefits of such types of measurements, they are not commonly used because of their high cost. This study introduces a series of empirical equations for constructing a partial pore-aperture-size distribution curve from routine core analysis for the highly permeable rocks. Bassem Nabawy received his M.Sc. degree in petrophysics, magnetism, and sedimentology from Cairo University, and his Ph.D. in the same field from Ain Shams University, Cairo. He is a petrophysicist. His research concerns matching the rock-pore fabrics to define the preferred fluid migration paths. Yves Géraud received his Ph.D. from the University of Marseilles in rock physics. He is a Maitre de Conférences in the University of Strasbourg. His research concerns porosity structures at various scales and their relationships with transfer properties in various geological contexts. Pierre Rochette received his Ph.D. from the Université Joseph Fourier in Grenoble in 1983. He has mainly worked on rock magnetism together with other petrophysical markers of rock fabric and mineralogical composition. Nicolas Bur received his M.Sc. degree from the University of Strasbourg on physical properties of Nubian sandstones. He is preparing a Ph.D. thesis on the petrophysical properties of concretes and the influence of different external factors of drying on the microstructural parameters.
Print ISSN:
0149-1423
Electronic ISSN:
1943-2674
Topics:
Geosciences
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