Rayleigh wave at composite porous half space saturated by two immiscible fluids

•Rayleigh wave on composite porous medium containing immiscible fluids is investigated.•Phase speed of Rayleigh wave increases in unsaturated medium.•Increase in porosity increases the phase speed of Rayleigh wave.•Viscosity of the fluids causes energy loss and results in higher attenuation of Rayleigh wave.