A novel velocity prediction approach in double-porosity media using the Biot-Rayleigh theory

摘要

Wave propagation induces local fluid flow (LFF) between the inclusions and the host media due to their dissimilar compressibilities. LFF mechanism is the dominate theory on explaining the velocity dispersion and attenuation. In general, it can be well characterized by the Biot-Rayleigh theory in the case of double-porosity media. However, the obtained dry rock bulk modulus is not accurate enough for the specific high fluctuation media, in which the compressibilities of inclusion and host media are significantly different. In this paper, a modified approach for obtain dry rock bulk modulus is proposed on the basis of the original Biot-Rayleigh theory in double-porosity media. It is worth noting that equivalent stress is replaced by equivalent strain in our proposed approach. This modified method is employed to model the frequency-dependent P- and S-wave velocities and attenuation, and its comparison with Pride's theory proves the feasibility of the proposed theory. We utilize a measured well data to demonstrate the accuracy of the predicted P- and S-wave velocities of different frequency bands using the proposed theory.