Physical Properties of Shaly - Sand Reservoirs: Saffron Field, Offshore Nile Delta, Egypt

Abstract

The Saffron gas Field is in the Scarab-Saffron Development Lease in the offshore Nile Delta. It was discovered by the Saffron-1 exploration well drilled in 1998 and appraised by Saffron-2 and Sapphire-3 wells. Saffron is a stacked channel system and consists of 6 different reservoirs with differing levels of connectivity between them. It can be interpreted as deep-water canyon fill deposits on a delta-front slope. Some physical properties of 4 full diameter core samples (approximatly164 core plugs) obtained from the Saffron-2 borehole were petrophysically analysed. Helium porosity, horizontal and vertical permeability, grain density and electrical resistivity were laboratory measured. Several bivariant plots were accomplished such as porosity- permeability; grain density, formation resistivity factor; cementation exponent and Winsaur’s multiplier (a) as well. Several regression line equations with robust coefficient of correlations were obtained to be used for reservoir characterization. On the other hand, numerous frequency histograms were built for most of the measured reservoir parameters to determine their type of distribution and other statistical parameters. Some important relations like cementation exponent versus multiplier (a) are performed which improves Archie’s general equation and subsequently the reservoir fluid saturation (Sw and/or Sh). The lack of stratification in sedimentary section represented by core numbers 4&5 of Saffron-2 well have severe consequences on measured reservoir parameters especially exposed by the porosity- permeability relation.