New guided wave in a poroacoustic layer

A poroacoustic Biot medium is used very often as the admissible approximation for a real oil-filled collector. For such a medium the shear stress of the matrix is equal to zero. In infinite poroacoustic space only fast P-waves and slow P-waves propagate with velocities ν ₁ and ν₂. The fast wave resulting from the solid and fluid parts moving in phase is similar to the ordinary compressional wave. The slow wave which is the consequence of the solid and fluid part moving out of phase attenuates very rapidly and therefore can not be observed at long distances. Earlier we have shown that an interference slow wave exists in the poroacoustic layer located inside the elastic medium. This wave has very low frequency and velocity and high amplitude. Here we show that in this model a new guided wave exists which has a number of unusual peculiarities