A case study of carbonate reservoir permeability determination using NMR log in one of the southwestern fields of Iran

Permeability is one of the most important parameters for characterization of hydrocarbon reservoirs that has a basic role in almost all of the petroleum engineering problems. Determination of reservoir permeability is usually done in core laboratories in a time consuming process. In the well test, the obtained average permeability is related to the drainage area. Due to cost, these two methods are not performed in the all wells, whereas well logging tools are generally performed in all wells. With progress of well logging tools, some researchers tried to estimate permeability from special well logs such as NMR directly. The data obtained from NMR was used as lithology independent data to estimate the water saturation and porosity, and also for analysis of pore space. One of the important parameters obtained from NMR is the transversal relaxation time (T2). In this work, NMR log measurement in a carbonate field was used to estimate the permeability using Timur, SDR and regression models. The results of the methods were compared against core permeability. The results show that SDR method is more accurate with the accuracy of 44.1% and the error of 23.12%.