Thermoacoustic action excites oscillations in a fluid saturated reservoir, which are accompanied by significant alternating stresses and received by the saturating fluid, contributing to the following main effects:
- increase in filtration volumes of mobile fluid at the existing pore radius and pressure gradient due to the “piston” effect, which leads to an increase in fluid withdrawal;
- Involvement in the filtration process of fluid immobile at the existing pore radius and pressure gradient due to overcoming viscoplastic forces holding the fluid, which leads to kintensification of oil withdrawal;
- reduction of oil viscosity due to destruction of its rheological structure by depolarisation of molecules and weakening of intermolecular bonds, as a result of which phase permeability of oil increases, whereas for water it remains unchanged, which contributes to reduction of watercutting of production;
- overcoming surface tension forces and, consequently, reducing the wetting angle between water and oil leads to an increase in the coefficient of oil displacement by water;
- segregation (separation) of oil and water in highly watered formations due to acceleration of gravitational separation of phases of different densities in the acoustic field favours redistribution of oil saturation and more complete oil recovery;
- the seismoelectric effect favours the destruction of near-wall fixed fluid layers of electrostatic nature represented by oil, so their destruction and involvement in the filtration process increases reservoir permeability and oil recovery factor;
- increase or restoration of permeability of the reservoir and bottomhole formation zone is achieved by cleaning of pore and perforation channels from mechanical impurities and high-viscosity deposits, as well as by disruption of surface liquid layers, which leads to an increase in the effective cross-section of pore channels and involvement of stagnant formation zones in the filtration process.
