Formation and ultrasonic removal of fouling particle structures in a natural porous material

Formation and ultrasonic removal of fouling particle structures in a porous material (caused by the flow of a liquid with small through the material) was studied with natural sandstone. Fouling particles were generated inside the sandstone by changing the composition of the liquid from a 2% KCl brine solution to fresh water. The influence of liquid velocity, particle concentration and ratio of particle diameter to pore diameter on the permeability decrease due to the fouling particles is as anticipated from the formation of particle bridges inside the sandstone. The removal of fouling particles by high frequency acoustic waves also was investigated. The influence of fluid velocity, material permeability and acoustic power input on the cleaning efficiency indicates again that fouling is caused by particle bridges inside the sandstone. The understanding of the formation and ultrasonic removal of fouling particle structures in a porous material is of importance for the design of ultrasonic tools for cleaning the near wellbore region of oil reservoirs.