Elastic wave propagation and scattering in prestressed porous rocks

作者：Li-Yun FU,Bo-Ye FU,Weijia SUN,Tongcheng HAN,Jianlin LIU

摘要：Poro-acoustoelastic theory has made a great progress in both theoretical and experimental aspects,but with no publications on the joint research from theoretical analyses,experimental measurements,and numerical validations.Several key issues challenge the joint research with comparisons of experimental and numerical results,such as digital imaging of heterogeneous poroelastic properties,estimation of acoustoelastic constants,numerical dispersion at high frequencies and strong heterogeneities,elastic nonlinearity due to compliant pores,and contamination by boundary reflections.Conventional poroacoustoelastic theory,valid for the linear elastic deformation of rock grains and stiff pores,is modified by incorporating a dualporosity model to account for elastic nonlinearity due to compliant pores subject to high-magnitude loading stresses.A modified finite-element method is employed to simulate the subtle effect of microstructures on wave propagation in prestressed digital cores.We measure the heterogeneity of samples by extracting the autocorrelation length of digital cores for a rough estimation of scattering intensity.We conductexperimental measurements with a fluid-saturated sandstone sample under a constant confining pressure of 65 MPa and increasing pore pressures from 5 to 60 MPa.Numerical simulations for ultrasound propagation in the prestressed fluid-saturated digital core of the sample are followed based on the proposed poro-acoustoelastic model with compliant pores.The results demonstrate a general agreement between experimental and numerical waveforms for different stresses,validating the performance of the presented modeling scheme.The excellent agreement between experimental and numerical coda quality factors demonstrates the applicability for the numerical investigation of the stress-associated scattering attenuation in prestressed porous rocks.

发文机构：Key Laboratory of Deep Oil and Gas Laboratory for Marine Mineral Resources Key Laboratory of Earth and Planetary Physics Institutions of Earth Science College of Earth and Planetary Sciences

关键词：Poro-acoustoelasticitywithcompliantporesElasticwavesPrestressedporousrocksNumericalmodelingStressinducedscatteringattenuation

分类号： P744.4[天文地球—海洋科学]