Condensate blockage removal using microwave and ultrasonic waves: Discussion on rock mechanical and electrical properties

Condensate formation near the wellbore is considered as one of the challenging problems affecting the production from a gas reservoir. Two types of mechanical and electromagnetic (EM) waves were implemented to remove this production barrier. Two core plugs with different mechanical and electrical properties were saturated with condensate fluid belonging to a gas field in the south of Iran and then subjected to the ultrasonic (US) waves with two frequencies of 37 and 80 kHz at different powers and time durations. Besides, the saturated plugs were exposed to the microwaves (MWs) with different powers at an identical wave frequency of 2.45 GHz. The experimental results showed that the ultimate removal factors from the plugs using the US and MW treatments varied at different conditions and mediums. The condensate removal efficiency from the plug (2) was higher than the plug (1) at both treatments. This could be explained by the mechanical, petrophysical, and electrical properties of both plugs. The acoustic impedance of the plug (2) was obtained 2.6 folds of the plug (1). More acoustic impedance gives rise to more local pressure disturbance and more external force to overcome the liquid surface tension. The ultimate condensate removals from the plug (2) using the US treatment at the highest powers were obtained almost 7% and 31% at the frequencies of 37 kHz and 80 kHz, respectively. Similarly, the ultimate condensate removal of the plug (1) at the highest power was obtained 2.4% and 16.9% at the frequencies of 37 kHz and 80 kHz, respectively. The ultimate condensate removals from the plugs (1) and (2) were 19% and 100%, respectively, in the MW treatment at the highest power level. As it was obvious from the temperature profile of the plugs, the dominant mechanism of the MW treatment for condensate removal was the dissipation of the EM wave energy. The composition of the plugs showed that the dielectric constants were approximately equal. Hence, minerals of both rocks had the same electrical behavior. Higher porosity of the plug (1), which resulted in more saturation with lower dielectric fluids, gave rise to a reduction in average dielectric constant. In other words, less average dielectric constant resulted in less temperature raising. © 2020 Elsevier B.V.