Effects of reservoir rock pore geometries and ultrasonic parameters on the removal of asphaltene deposition under ultrasonic waves

Asphaltene deposition around the wellbore is a major cause of formation damage, especially in heavy oil reservoirs Ultrasonic stimulation, rather than chemical injection, is thought to be a more cost-effective and environmentally friendly means of removing asphaltene deposition. However, it seems to be unclear how crucial features like reservoir pore geometries and ultrasonic parameters affect this ultrasound treatment.

In this work, five two-dimensional glass micromodels with different pore geometries were designed to assess the impact of pore geometries on the ultrasonic removal of asphaltene deposition. Experiments were undertaken in an ultrasound bath at a set frequency (20 kHz) and adjustable powers (100–1000 W). Direct image analysis before, during and after sonication was used to assess the impact of pore geometry and a change in ultrasonic parameter on the removal of asphaltene deposition. The effectiveness of ultrasound treatment at various sonication periods were found to be reliant on the pore geometries of the individual micromodels. For micromodels with throat sizes 300 µm and pore shapes as circle, square and triangle, an increase in ultrasonic power from 400 to 1000 W resulted in an increase in the percentage of removed asphaltene deposition after 2 h from 12.6 to 14.7, 11.5 to 14.63, and 5.8 to 7.1 percent, respectively.