Time-reverse location of microseismic sources in viscoelastic orthotropic anisotropic medium based on attenuation compensation

• Published in: Applied geophysics Vol. 17; no. 4; pp. 544 - 560
• Main Authors: Jie, Tang, Ying-Chang, Liu, Lei, Wen, Cong, Li
• Format: Journal Article
• Language: English
• Published: Beijing Chinese Geophysical Society 01.12.2020; Springer Nature B.V; School of Geosciences,China University of Petroleum,Qingdao 266580,China
• Subjects: Algorithms; Anisotropic media; Anisotropy; Attenuation; Back propagation; Compensation; Earth and Environmental Science; Earth Sciences; Elastic media; Energy dissipation; Energy exchange; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Microseisms; Model testing; Oil reservoirs; Oil shale; Sedimentary rocks; Seismic Modeling and Wave Propagation; Shale; Shale gas; Shale oil; Symmetry; Theoretical analysis; Velocity; Viscoelasticity; Wave equations; microseismic; time-reverse location; Viscoelastic orthotropic anisotropy; fractional order; attenuation compensation
• ISSN: 1672-7975; 1993-0658
• DOI: 10.1007/s11770-020-0833-7

Time reversal is a key component of time-reverse migration and source location using wavefield extrapolation. The implementation of time reversal depends on the time symmetry of wave equations in acoustic and elastic media. This symmetry in time is no longer valid in attenuative medium. Not only the velocity is anisotropic in shale oil and gas reservoirs, but also the attenuation is usually anisotropic, which can be characterized by viscoelastic orthotropic media. In this paper, the fractional order viscoelastic anisotropic wave equation is used to decouple the energy dissipation and the velocity dispersion. By changing the sign of the dissipation term during backpropagation, the anisotropic attenuation is compensated and the time symmetry is restored. The attenuation compensation time-reverse location algorithm can effectively locate the source in viscoelastic orthotropic media. Compared to cases without attenuation compensation or using isotropic attenuation compensation, this method can remove location error caused by anisotropic attenuation and improve the imaging effect of the source. This paper verifies the effectiveness of the method through theoretical analysis and model testing.