New insight in crude oil oxidation study: Using nuclear magnetic resonance spectroscopy

Abstract

© SGEM2018. In-Situ Combustion is one of the most important and promising methods for enhancing oil recovery for both light and heavy crude oils from reservoirs. In this method air is injecting into the oil reservoirs and causes ignition and in the next step it effects combustion inside of reservoirs. Nuclear Magnetic Resonance (NMR) spectroscopy as a fast and accessible technique was used to monitoring the light and heavy crude oils oxidation behavior. Herein, we investigated two light and heavy crude oils based on temperature dependence oxidation process during low-temperature oxidation in a wide temperature region from room temperature to 180 ºC. In this research, we simulated air injection method into the reservoirs through bubbling air into the samples during heating. At any certain temperature with the help of Hydrogen (1 H) spectroscopy we monitored the temperature effect on oxidation of oil in the presence of air. In continue due to less sensitive of13 C NMR we applied Fourier-Transform Infrared spectroscopy (FTIR) as an accessible method for monitoring and more evaluation the new oxygen-containing compound such as carbonyl group. Infrared spectroscopy showed that during crude oil oxidation the abundance of Chemical changes occurred gradually and systematically with the increasing of temperature. For the light oil we observed mass lose that it can be belongs to evaporation of some light hydrocarbons and some gases such as CO2 and H2S. The NMR results showed that crude oil oxidation causes to produce oxygen content compound inside of oil such as carbonyl compound. This phenomena can be open new route to studying crude oil oxidation using NMR spectroscopy and it will be new clue for understanding the route of crude oil oxidation mechanisms inside of reservoirs.