SPECTRAL BEHAVIOR OF BIHARMONIC ACOUSTIC WAVES DURING THEIR ACTION ON NONLINEAR GEOPHYSICAL MEDIUM

Purpose. Acoustic methods are used for acting on geological medium in order to increase oil and gas reservoir recovery. To enlarge possibilities of acoustic effect on hydrocarbon layers the authors have studied spectral characteristics of biharmonic acoustic effect on a layer. Design/methodology/approach. Equations of non-linear acoustics were applied in this process, which can be reduced to equations of simple waves with the help of an alternating profile method. Findings. Based on solving the equation of simple waves for disturbance of arbitrary shape, we studied spectral characteristics of biharmonic signal which propagates in nonlinear geo-medium with m 1. We have found that the process of interaction of a strong signal with frequency 2? and a weaker signal with frequency ? is sensitive to the shift of the phase ?. In case of interaction of a weak signal with frequency ?, shifted by phase ?, with intense wave of pumping with frequency 2?, there appears a nonlinear effect of parametric amplification of a weak signal. We have revealed that amplification of the weak signal pulse height is observed in the case of the shift of the phase in the range of ? = 45°...135°. The biggest amplification is observed when the angle of the shift of the phase ? = 90° and reaches 3,7. When ? = 0°...45°; ?35°...180° the amplitude of a weak signal decreases. Practical value/implications. The results obtained can be used for developing promising wave methods of structured hydrocarbon-bearing layers processing, where the proposed widening of acoustic processing range is connected with the enhancement of the amplitude of resonance frequency wave by applying the energy of an intensive injection wave with higher frequency.