Electro-acoustic excitation of the interface

Methods that use directed acoustic [14,128] and electric fields [104,115] have shown a promise in oil recovery in the past. These methods are great candidates to not only facilitate oil recovery, but also reduce CO₂ emissions to a minimum. However, they have not found big commercial success due to poor understanding of the underlying mechanisms that facilitate the recovery. This paper is focused on breaching this gap by summarizing the main theories and experimental work done in the fields of acoustic and electric wave propagation though liquids, their interfaces and saturated porous media. The main theories of the acoustic and electric wave propagation through liquid and saturated porous media are outlined and discussed here. Key physical mechanisms that occur in the reservoir oil and water phases and at their interface during acoustic and electric wave propagation are identified. The development of the Maxwell stress theory of the liquid-liquid interface under the influence of the electric field by Melcher, Smith, Taylor and Lin et al. is shown to be a useful tool to estimate the critical voltage that disturbs a liquid-liquid interface [78,112,120]. Important aspects in wellbore acoustic transducer design and its selection to fit into the reservoir conditions are covered and scrutinized [66,101]. Characteristics of the magnetostrictive devices are shown to fit reservoir conditions the best.