f Review of using acoustic and seismic waves for stimulation of oil reservoirs - Methods and results

Numerous observations, accumulated during the history of various oil fields development show that seismic waves generated from earthquakes and even traffic noise may affect oil production. The interaction of elastic waves with an oil reservoir causes the different physical effects which generally increase the permeability of porous medium and the mobility of oil in it. Among these effects the most important are the destruction of liquid films adsorbed at gore boundaries which considerably reduce the effective crosssection of gore throats, the coalescence of oil droplets; strong acoustic fields cause reduction of oil viscosity and surface tension, induce acoustic flows and cavitation, and heat the medium. The effect of elastic waves on the permeability of saturated media has been confirmed in the numerous laboratory experiments. Duhon (1964) observed a considerable increase in oil recovery from sandstone due to ultrasonic excitation. Fairbanks and Chen (1971) observed an acceleration of up to 18 times of oil percolation rate through the sandstone when the system was exposed to strong acoustic excitation. Results of laboratory investigations showed that elastic waves also increase the rate of displacement of hydrocarbons by gas and water, and accelerate the gravity segregation of oil and water in reservoirs.