Abstract
Production of oil and gas wells is often reduced due to damage in the near-wellbore region related to the drilling process. In many instances, the damage is caused by the interaction of the reservoir formation with drilling and completion fluids. This damage can increase during the life-time of the well due to influx of formation damage (fines, scale, asphalthenes, etc). An example is formation fines plugging a slotted liner or screen.
High frequency sonic waves have been used in many industrial applications to remove contaminants like dirt, oil, and grease from parts immersed in fluids. An obvious extension of this application is the removal of wellbore impairment by exposing it to high frequency acoustic waves. Although the concept is old, successful large-scale application of acoustic well stimulation is not yet common. During the last decade the manufacturing of high-power piezo-electrical elements developed fast and opened the potential to design a downhole acoustic cleaning tool.
The advantages of an acoustic cleaning tool is the selectivity of the treatment compared with conventional matrix acidizing treatment. Also the need for large quantities of chemicals (acid, corrosion inhibitor etc.) can be eliminated.
In previous publications the potential of acoustic cleaning has been reported using experimental results obtained in a laboratory set-up using linear acoustic waves. In this paper the results will be presented on the cleaning of mud damage using a prototype acoustic tool in a radial geometry.
