Applicability of Classical Permeability Estimation Models Based on NMR Logging in Tight Sandstones

Abstract

Permeability cannot be directly predicted from porosity by using a single function in tight sandstones reservoirs due to the extreme heterogeneity. The hydraulic flow unit (HFU) approach and classification scale method (CSM) are available in permeability prediction, while they are all significant time-consuming. In this paper, based on the analysis of the proposed data sets of lab NMR experimental measurements by Xiao et al. (2012; 2013), the applicability of the classical SDR (Schlumberger Doll Research) and Timur-Coates models, which are used to estimate permeability from NMR logging is analyzed. A field example shows that the Timur-Coates model is valuable in tight sandstone permeability estimation once the involved input parameter of irreducible water saturation (Swi) can be accurately calculated without acquiring T2cutoff. While the SDR model is not available because the effects of hydrocarbon to NMR spectra cannot be removed.