Application of NMR Method to Assess the Efficiency of Enhanced Oil Recovery Measures

The paper presents the results of nuclear magnetic resonance (NMR) study of oil samples taken from production wells from the fields of the Republic of Tatarstan before and after the application of one of the enhanced oil recovery (EOR) methods, namely, flow rejection technology based on injection of microgel compositions into injection wells. A comparative analysis of proton NMR spectra and diffusion attenuation of spin echo in spectrally resolved mode was carried out in order to determine the influence of the used technology on the characteristics of recoverable oil. It is shown that after application of EOR for the majority of wells in the oil composition an increase in the share of hydrocarbon components with large values of molecular weight is registered, and for a number of wells a change in the degree of aromaticity of recoverable hydrocarbons is also recorded. The results obtained are interpreted as a consequence of the inclusion in the development of new reservoir zones, previously not involved in oil production, and demonstrate the potential of NMR method for assessing the efficiency of EOR.