Investigation of smart water imbibition assisted with microwave radiation as a novel hybrid method of enhanced oil recovery

Abstract

This research aims to investigate the efficiency of a new hybrid method of smart water imbibition assisted with microwave (MW) radiation. Some experiments including the contact angle measurement, attenuated total reflectance (ATR), zeta potential evaluation, oil viscosity measurement, and smart water imbibition were studied to find the effect of the MW radiation on the performance of the smart water imbibition. To capture the controlling mechanisms, it was essential to sustain the temperature in some of the MW treatments. Hence, the rock sections were treated by two methods of dry (MW treating the sections without immersion in the brine water) and immersed (MW treating the sections when they are immersed in the brine water) treatments. It was shown that the contact angle of an aged rock section could be reduced from 170° at the initial condition to almost 37° due to treating by smart water and the MW radiation. Divalent cations of Mg2+ and SO42- were discovered to be more efficient in the wettability improvement than Ca2+, and this fact was discussed in detail from thermodynamic and kinetic points of view. Also, it was found that the MW thermal effect is not the only reason for the wettability improvement and organic compound desorption, but also the MW treatment could destabilize the organic compounds on the rock surface through generating oscillating electric fields. This fact was confirmed by the results of the immersed MW treatment, where the contact angle reduction was found to be almost as efficient as the dry MW treatment. Based on the ATR spectrums, the MW radiation can desorb the polar and non-polar compounds in two different mechanisms of thermal desorption and destabilization caused by oscillating electric fields. Furthermore, it was shown that the oil viscosity was reduced due to temperature rising caused by the microwave treatment, but when the temperature of the oil sample reduced to the room temperature, the viscosity reduction was not observed. The oil viscosity, after the treatment for 2 min, with the radiation power of 20, 40, 60, 80, and 100 maximum power increased to 52.5, 53.1, 55.5, 54.2, and 53.1 cp, respectively. Finally, it was shown that the oil recovery was increased 9% during the MW radiation for 16 min in the smart water imbibition test. Based on the observed results in this research, it is concluded that the hybrid of smart water imbibition assisted with MW radiation could be considered as a novel EOR method resulting in more oil recovery.