Application of ultrasound wave for stimulation of asphaltene damaged reservoir rocks: An experimental study

In this study, application of ultrasound wave for permeability enhancement of reservoir rocks was experimentally examined. In this regard, a specific core holder apparatus was designed with the ability of in-situ exposure of ultrasound to the plug in a high-pressure condition, which is a better representative of ultrasound application in real wellbores. The effect of ultrasound power and exposure time as well as probe-plug distance on permeability stimulation was evaluated. The results showed that ultrasound could stimulate the permeability of asphaltene-damaged rocks, in which its efficiency was significant in sandstone rock. Analysis of asphaltene content in the output uid showed that, as a result of ultrasound exposure, 84% of deposited asphaltenes in the sandstone plug were removed, corresponding to 67% of permeability recovery. It was also found that the stimulated permeability increased with increasing exposure time and power, while it decreased with increasing probe-plug distance. However, an optimum value for exposure time and power, after which the permeability recovery was not significantly enhanced, was observed. Analysis of experiments also showed that probe-plug distance had the most prominent effect on recovery of damaged permeability in comparison to ultrasound time and power.