Technology of removing near wellbore inorganic scale damage by high power ultrasonic treatment

The effects of ultrasonic treatment and the influence of ultrasonic parameters, process parameters and core physical parameters on the results of ultrasonic treatment for removal of near wellbore inorganic scale damage were studied using the self-developed dynamic simulation experimental apparatus of fluctuating oil extraction technology and the artificial cores damaged by inorganic scale. The fundamental dynamical mechanism of ultrasonic treatment was also discussed. On the basis of the study, field experiments were conducted with the self-developed high power ultrasonic construction equipment. The results showed that transducer frequency, transducer power, ultrasonic processing time and core initial permeability all influence the plugging removal effect. The plugging removal effect gets better with the increase of transducer frequency and power. The optimal processing time is about 80–120 min. Field tests carried out in low permeability reservoirs in northern Shaanxi and in the Daqing Oilfield showed that ultrasonic treatment can increase the production and injection remarkably, confirming the laboratory results.