Ultrasonic removal of organic deposits and polymer induced formation damage

Experiments were conducted that evaluate the feasibility of using high intensity acoustic sources to remove near wellbore formation damage caused by organic deposits (paraffins and asphaltenes) and polymers (HEC). It is shown that mechanical agitation provided by the acoustic waves effectively re-suspends the paraffin and restores the effective permeability of the core to oil to its undamaged condition in a relatively short period of time. The depth of treatment is approximately 12 to 15 cm. This suggests that an acoustic source with or without solvents may provide an effective method of removing paraffins from the wellbore and the near wellbore region. Acoustics was not found to be as effective at restoring the permeability of cores damaged by polymers (HEC). Only small (factor of 1.5) increases in permeability were obtained for both poorly mixed and well mixed HEC. Experiments conducted over a range of frequencies and acoustic intensities allow us to specify the design requirements for a field deployable transducer. Eight such transducers have been incorporated into a through tubing tool that has recently been built and is now available for field testing. Our results demonstrate that acoustic cleaning may be a viable method for cleaning both the wellbore and near wellbore region when paraffin precipitation is a problem. The method would be particularly effective at treating long sections of pay (horizontal wells) where chemical methods may be too expensive. Acoustic cleaning is much less effective for treating polymer damage problems