Evaluating Heterogeneity of Heavy Oil Viscosity According to NMR Core Analysis

Abstract

The paper presents the results of laboratory nuclear magnetic resonance (NMR) studies of oil-saturated core samples of the Sheshminskian horizon of heavy oil fields in the Republic of Tatarstan. The analysis of the results showed that T2 spectra of oil recovered via centrifugation from the pre-heated core and oil remaining in the core are substantially different from each other. Magnetic relaxation rate of residual oil is much faster, and thus its viscosity is significantly higher than that of the recovered oil. The difference can be up to ten times. The spectrum of relaxation times T2 in the original oil-saturated core integrates information about all the fluid contained in the rock. The results and findings underscore the ability of NMR logging tools to characterize the entire oil fluid in the rock in situ.