Experimental Investigation of the Influence and Comparison of Microwave and Ultrasonic Waves on Carbonate Rock Wettability

In this research, the influence and comparison of ultrasonic and microwaves on the wettability of carbonate rock have been investigated. Wettability is one of the most fundamental parameters of the oil reservoir, according to which the fluid movement in the porous medium can be examined. The aged thin sections were placed in a microwave oven and an ultrasonic bath and they were exposed to radiation for 2-10 minutes. Using the contact angle analysis, it was observed that the angle between the rock and oil drop of microwaved and ultrasonicated samples changed by 57 and 71 degrees, respectively. Contact angle and temperature changes started faster for the ultrasonicated samples. The surface charge of the rocks was determined by zeta potential analysis, and it was found that in both samples, in the first minutes of radiation, negatively charged colloids were liberated from the samples by absorbing the waves, which reduced the surface negative charges, and with the continued radiation, positively charged colloids were decreased due to the evaporation of light oil compounds. The reduction of zeta potential occurred faster for the ultrasonicated sample, but the rate of decrease was lower. By examining Fourier-transform infrared spectroscopy (FTIR) results, it was concluded that the heavy compounds on the surface of the samples were cracked and turned into lighter hydrocarbons, and the changes for both samples were almost equal. Also, the polar compounds, sulfur, and nitrogen in samples increased, decreased, and decreased respectively for both samples, and these changes were more for the ultrasonicated samples.