Calculation of petrophysical properties for Mishrif carbonate reservoir

Abstract

The accurate calculations of petrophysical properties in carbonate reservoirs are the most challenging aspects of well log analysis. Many equations have been developed over the years based on known physical principles or on empirically derived relationships, which are used to calculate carbonate rock petrophysical properties. Carbonate reservoirs in the Middle East are very heterogeneous in terms of rock types. Therefore the reservoir should be split into layers on the basis of the dominant rock type in order to define average values and trends of petrophysical parameters in the reservoir rock. The saturation exponent (n) and cementation exponent (m) are calculated from well log data using Pickett method. The study made across the Mishrif carbonate formation, which is the shallowest formation of the hydrocarbon bearing zone in the NS oil field in the Middle East. Results show that the average formation water resistivity (Rw= 0.0243), average mud filtrate resistivity (Rmf= 0.199), Irreducible Water Saturation (Swi=0. 18), and Archie's parameters (m=1. 78, n= 2, and a=1). While porosity, true resistivity, and water saturation values with depth of formation were calculated by using Interactive Petrophysics software (IP V3.5, 2008). The computer process interpretation (CPI) illustrates that the shale member splits the Mishrif formation into two parts; Upper and Lower Mishrif. This study is a step to investigate petrophysical properties, which used to calculate water saturation that should use to estimate original oil in place and detected the perforation zones.