Estimation of Permeability and Pore Size Distribution Using Core Data and NMR Log Data in One of Heavy Oil Reservoirs in Iran

Permeability is one of the most important properties of hydrocarbon reservoirs. Pore radius distribution is another parameter having a significant role in determining permeability, enhancing recovery and retaining cap rock's hydrocarbon column. In this study, we have tried to investigate permeability and pore size distribution of one of carbonate reservoirs containing heavy oil in south of Iran. Two methods used to estimate these parameters are: NMR log and core data. The result of permeability and pore size distribution by using NMR log method is compared to the result by using coring analysis and the tests done on cores. In addition to more accurate comparison between the results of permeability by using NMR log method and permeability of coring operation, we have used three NMR based models (freefluid model, average-T2 model, Swanson model) by using Geolog software. At the end the correlation coefficients are compared and the best method for determining permeability in these formations is introduced. We introduced a new model for determining pore size distribution using NMR log. This model which works by combining core data with NMR log data would be useful in situations which NMR device is not available.