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A nonparametric spectrum estimation method for dispersion and attenuation analysis of borehole acoustic measurements

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Petroleum Science 2023年第1期20卷 241-248页

作者： Bing Wang Wei Li Qing Ye Kun-Yu Ma State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China Beijing Research Center Aramco AsiaBeijing100102China

dispersion and attenuation analysis can be used to determine formation anisotropy induced by fractures,or *** this paper,we propose a nonparametric spectrum estimation method to get phase dispersion characteristics and attenuation *** designing an appropriate vector filter,phase velocity,attenuation coefficient and amplitude can be inverted from the waveform recorded by the receiver *** analysis of this algorithm is compared with Extended Prony Method(EPM)and Forward and Backward Matrix Pencil(FBMP)*** on the analysis results,the proposed method is capable of achieving high resolution and precision as the parametric spectrum estimation *** the meantime,it also keeps high stability as the other nonparametric spectrum estimation *** last,applications to synthetic waveforms modeled using finite difference method and real data show its *** real data processing results show that the P-wave attenuation log is more sensitive to oil formation compared to S-wave;and the S-wave attenuation log is more sensitive to shale formation compared to P-wave.

关键词： dispersion analysis Attenuation factor Nonparametric spectrum estimation method Acoustic logging Fluid type evaluation

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analysis of high-frequency local coupling instability induced by multi- transmitting formula - P-SV wave simulation in a 2D waveguide

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Earthquake Engineering and Engineering Vibration 2017年第1期16卷 1-10页

作者： Xie Zhinan Zhang Xubin Institute of Engineering Mechanics China Earthquake Administration Key Laboratory of Earthquake Engineering and Engineering vibration of China Earthquake Administration Harbin 150080 China

Local coupling instability will occur when the numerical scheme of absorbing boundary condition and that of the field wave equation allow energies to spontaneously enter into the computational domain. That is, the two schemes support common wave solutions with group velocity pointed into the computation domain. The key to eliminate local coupling instability is to avoid such wave solutions. For lumped-mass finite element simulation of P-SV wave motion in a 2D waveguide, an approach for stable implementation of high order multi-transmitting formula is provided. With a uniform rectangular mesh, it is proven and validated that high-freqaency local coupling instability can be eliminated by setting the ratio of the element size equal to or greater than x/2 times the ratio of the P wave velocity to the S wave velocity. These results can be valuable for dealing instability problems induced by other absorbing boundary conditions.

关键词： absorbing boundary condition local coupling instability dispersion analysis group velocity multi-transmitting formula

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Effect of Element Distortion on the Numerical dispersion of Spectral Element Methods

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Communications in Computational Physics 2011年第4期9卷 937-958页

作者： S.P.Oliveira G.Seriani Departamento de Matematica Universidade Federal do ParanaCuritiba-PR81531-980Brazil Istituto Nazionale di Oceanografia e di Geofisica Sperimentale Borgo Grotta Gigante42/cSgonico(TS)34010Italy

Spectral element methods are well established in the field of wave propagation,in particular because they inherit the flexibility of finite element methods and have low numerical dispersion *** latter is experimentally acknowledged,but has been theoretically shown only in limited cases,such as Cartesian *** is well known that a finite element mesh can contain distorted elements that generate numerical errors for very large *** the present work,we study the effect of element distortion on the numerical dispersion error and determine the distortion range in which an accurate solution is obtained for a given error *** also discuss a double-grid calculation of the spectral element matrices that preserves accuracy in deformed geometries.

关键词： Spectral element method dispersion analysis slivering

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A meshfree method for inverse wave propagation using collocation and radial basis functions

A meshfree method for inverse wave propagation using colloca...

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第十一届南方计算力学学术会议（SCCM-11）

作者： Lihua Wang Zhen Wang Zhihao Qian School of Aerospace Engineering and Applied Mechanics Tongji University

A stable and highly accurate meshfree scheme based on strong form collocation associated with radial basis functions and explicit time integration is proposed to solve ill-posed inverse wave propagation problems. Tikhonov regularization technique and the L-curve criterion are employed to deal with the noise measurement data before solving the governing equation to get a stable solution. Appropriate weights are first derived for imposing boundary conditions and known conditions from the measurement data to yield the optimal convergence for inverse problems. Compared to the required iterative procedures in common methods, no iteration is needed in the proposed method which leads to the time-saving computation and avoids the instability resulting from the iterative methods. dispersion analysis describes that this method has much less dispersion error than the classical finite element method(FEM) and popular weak form meshfree methods, and stability analysis is performed to predict the critical time step for the explicit time integration. Another outstanding advantage of this method is it’s effortless to extend the solution scheme of one-dimensional inverse problem to high-dimensional inverse problems. Furthermore, the influences of the high noise into measurement data are evaluated, which demonstrate that even handling with very high noise in the input data the proposed algorithm can achieve stable and high-accuracy solutions.

关键词： strong form collocation radial basis functions ill-posed inverse wave propagation problem Tikhonov regularization dispersion analysis stability analysis

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