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Signal separation using unsupervised learning with local uncorrelated constraints: Applications to ground-roll contaminated data sets

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Geophysics 2025年第4期90卷 V313-V323页

作者： Sun, Xu Chai, Xintao Yang, Qingyi Zhai, Meiyuan Gu, Hanming School of Geophysics and Geomatics DeepResearch Group The Home of SeisPro Hubei Subsurface Multi-scale Imaging Key Laboratory Wuhan China Shandong Electric Power Engineering Consulting Institute Co. Ltd Jinan China

Signal/noise separation is a fascinating field in geophysics (e.g., separating ground-roll contaminated shot gathers into ground roll and other signals or splitting noisy seismic sections into random noises and noise-free signals). Local orthogonalization (LO) stands out as one of the most intriguing theories initially conceived for random noise attenuation. It postulates that the signal and noise should be orthogonal to each other, implying that they exhibit no correlation. Drawing inspiration from the LO theory and driven by advancements in artificial intelligence (AI) technologies, we innovatively explore a signal separation method using unsupervised learning (USL) with local uncorrelated constraints and apply it to ground-roll contaminated data sets. We establish one neural network (NN) comprising two parallel branches to produce two distinct outputs. The input of the NN consists of the band-pass-filtered low-frequency component of the raw shot gather. The outputs of the NN correspond to the separated ground roll and the remaining low-frequency components. Because our signal separation method is label free, we incorporate one data loss function and two local uncorrelated losses (defined by the local correlation coefficient between the two separated signals) to guide the NN learning process. The data loss ensures that the signal separation remains faithful to the raw data. One of the local uncorrelated loss functions aims to minimize the correlation between the separated ground roll and the remaining low-frequency components. The second local uncorrelated loss is designed to minimize the correlation between the separated ground roll and the remaining low-and high-frequency components. Overall, our work combines the principles of LO, USL, and AI advancements to tackle signal separation challenges in geophysics. Applications to two field data sets demonstrate the feasibility of our method. We share our code and data via a public repository. © 2025 Society of Explor

关键词： Unsupervised learning

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Estimation of lunar major elemental abundances in Chang'E-3 landing site based on Active Particle-induced X-ray Spectrometer (APXS)

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ASTROPHYSICS AND SPACE SCIENCE 2015年第1期359卷 1-9页

作者： Wang, Jian Wang, Xianmin China Univ Geosci Inst Geophys & Geomat Hubei Subsurface Multi Scale Imaging Key Lab Wuhan 430074 Peoples R China

Elemental abundance provides an effective vehicle to understand lunar petrologic characteristics and evolutional history. The APXS mounted on the Yutu rover provides a valuable opportunity to determine the major elemental abundances in lunar soil within a short distance. In this study, we processed the APXS spectra including energy calibration, dead time correction and nonlinear least-squares fitting, and determined the abundances of the lunar major elements using the fundamental parameter method. In the calculation of X-ray fluorescence yield, a finite element method (FEM) was employed to improve the accuracy. The major elemental abundances derived from Chang'E-3 (CE-3) APXS possess a good consistency with the result of LP-GRS (Lunar Prospector gamma-ray spectrometer) data in the landing region. Compared with the chemical composition of the returned lunar rock samples, we draw the conclusion that the lunar soils in CE-3 landing site are fragments of mare basalts. Our conclusion is supported by the geological map of Mare Imbrium.

关键词： Chang'E-3 APXS Elemental abundance Lunar soil

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3D CSEM simulation and the effects of electrical anisotropy and topography 89

3D CSEM simulation and the effects of electrical anisotropy ...

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Society of Exploration Geophysicists International Exposition and Annual Meeting 2019, SEG 2019

作者： Peng, Ronghua Hu, Xiangyun Liu, Yajun China University of Geosciences Wuhan China Hubei Subsurface Multi-scale Imaging Key Laboratory Wuhan China

Controlled-source electromagnetic (CSEM) method has evolved into an established geophysical technique and found its increasing applications on land, marine and airborne. However, irregular undulated earth surface and electrical anisotropy of geological formations are often encountered in practical CSEM surveys. In such cases, reliable data interpretation requires a knowledge of quantitative estimates of the influence of topography and electrical anisotropy on CSEM data. In this study, we have developed a finite element CSEM modeling scheme and investigated the effects of anisotropy and topography on CSEM responses. The results demonstrate that both the anisotropy and topography can affect CSEM responses, but to different extents. The effects of electrical anisotropy and topography have to be taken into account for reliable CSEM data interpretation in practice. © 2019 SEG

关键词： Topography

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Curie point depth estimates based on spectrum analysis from aeromagnetic data in Guangxi Province, China 88

Curie point depth estimates based on spectrum analysis from ...

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88th Society of Exploration Geophysicists International Exposition and Annual Meeting, SEG 2018

作者： Zhi, Jianli Li, Hailong Du, Jinsong Liang, Qing Liu, Yiming Chen, Chao Hubei Subsurface Multi-scale Imaging Key Laboratory Institute of Geophysics and Geomatics China University of Geosciences China Guangxi Academy of Geophysical Exploration China Hubei Subsurface Multi-scale Imaging Key Laboratory Institute of Geophysics and Geomatics China University of Geosciences State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences United States Hubei Subsurface Multi-scale Imaging Key Laboratory Institute of Geophysics and Geomatics China University of Geosciences China

The Guangxi province is considered as a unique region in southeastern China due to its geographical location, tectonic and thermal activities. It is located geographically at the crossroads of Yangtze plate and Cathaysia landmass constituting a collision zone between the two blocks. In this study, we aim to further understand the lithospheric magnetic structure, thermal activity, and seismicity through mapping the Curie point depth (CPD) for Guangxi. The CPD are obtained by the method of power-density spectrum analysis based on the aeromagnetic anomaly data. Results of this study indicate that the CPD of Guangxi at a depth of 19~40 km (indicate that the CPD over the study region ranges from 19 km to 40 km). We found a weakly negative nonlinear correlation between the CPD and heat flow. The Curie isotherm generally lies above the Moho in this region but deepens into the mantle in some locations, notably beneath the middle of Guangxi. Earthquakes concentrated in the concave field and transition band of the CPD. The distribution of faults and igneous rocks have significant influences on the CPD. © 2018 SEG.

关键词： Spectrum analysis

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Slip rate of the seismogenic fault of the 2021 Maduo earthquake in western China inferred from GPS observations

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Science China Earth Sciences 2021年第10期64卷 1363-1370页

作者： Yage ZHU Faqi DIAO Yuchao FU Chengli LIU Xiong XIONG Hubei Subsurface Multi-Scale Imaging Key Laboratory Institute of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074China

Seismic and field observations indicate that the Mw7.4 Maduo earthquake ruptured the Jiangcuo fault,which is a secondary fault~85 km south of the northern boundary of the Bayan Hor block in western *** kinematic characteristics of the Jiangcuo fault can shed lights on the seismogenic mechanism of this *** rate is one of the key parameters to describe the kinematic features of a fault,which can also provide quantitative evidences for regional seismic hazard ***,due to lack of effective observations,the slip rate of the Jiangcuo fault has not been studied *** this study,we consider the interaction between the Jiangcuo fault and the eastern Kunlun fault,and estimate the slip rates of the two faults using the interseismic GPS observations across the seismogenic *** inferred results show that the slip rates of the Jiangcuo fault and the Tuosuo Lake segment of the Kunlun fault are 1.2±0.8 and 5.4±0.3 mm a^(-1),*** the slip rate with the average slip inferred from the coseismic slip model,the earthquake recurrence interval of the Jiangcuo fault is estimated to be 1800700+3700 years(1100–5500 years).Based on the results derived from previous studies,as well as calculations in this study,we infer that the slip rate of the Kunlun fault may decrease gradually from the Tuosuo Lake segment to the eastern *** Jiangcuo fault and its adjacent parallel secondary faults may have absorbed the relative motion of blocks together with the Kunlun fault.

关键词： Maduo earthquake Fault slip rate Geodetic observation Kunlun fault Seismic hazard

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Gravitational quasinormal modes of a parametrized Schwarzschild metric

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Communications in Theoretical Physics 2023年第10期75卷 121-128页

作者： Kai Lin Hongsheng Zhang Hubei Subsurface Multi-scale Imaging Key Laboratory School of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074HubeiChina School of Physics and Technology University of Jinan336 West Road of Nan XinzhuangJinan 250022China

Recently,a parametrized Schwarzschild metric(PSM)was proposed,in which n=2 to solve the differences of mass of M87*from different *** find the axial gravitational quasinormal modes of this metric are unstable for n>*** decay rate of the quasinormal mode of the case n<1 is much smaller than the case n=1,which can be used to differentiate the PSM from a Schwarzschild one.

关键词： black hole quasinormal mode matrix method

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Stability analysis of constrained L1 inversion of gravity data for estimating discontinuous basement relief 9

Stability analysis of constrained L1 inversion of gravity da...

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9th International Conference on Environmental and Engineering Geophysics, ICEEG 2020

作者： Li, Jiawei Liang, Qing Hubei Subsurface Multi-scale Imaging Key Laboratory Institute of Geophysics and Geomatics China University of Geosciences Wuhan China

L1 inversion of gravity data is widely used to estimate the discontinuous relief of basement. We used the L1 inversion method to recover a complex model with faults, a smooth feature, and a V-shaped interface. The noise of data, the constraints with errors and the incorrect density contrast are considered in the stability analysis of inversion. The results show that the constrained L1 inversion of gravity data is stable and efficient for complex discontinuous relief of basement. © Published under licence by IOP Publishing Ltd.

关键词： Buildings

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Theoretical dispersion curves for borehole real-valued wave modes in vertically transverse isotropic formations

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Petroleum Science 2022年第6期19卷 2649-2662页

作者： Fu-Qiang Zeng Chao Li Hubei Subsurface Multi-scale Imaging Key Laboratory Institute of Geophysics and GeomaticsChina University of GeosciencesWuhan430074HubeiChina State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing100190China Beijing Engineering and Technology Research Center for Deep Drilling Exploration and Measurement Beijing100190China

The dispersion curves of real-valued modes in a fluid-filled borehole are widely used in acoustic well *** accurate dispersion curves are the precondition of theoretical analysis and inversion ***,these curves can be obtained by solving the conventional dispersion equation for isotropic formations and most vertically transverse isotropy(VTI)***,if the real-valued solutions exist when the radial wavenumbers for the formation quasi-P and quasi-S equals to each other,the existed methods based on the conventional dispersion equation could lead to incorrect results for some VTI *** studies have focused on the influence of these real-valued solutions on dispersion curve *** remove these real-valued solutions,we have proposed a modified dispersion equation and its corresponding solving *** solving the dispersion equation,the Scholte wave velocity of VTI formation at high frequency is used as the initial *** two synthetic examples including fast and slow VTI formations validate that these real-valued solutions do not contribute to the wavefield,and the new dispersion curve extraction method is suitable for all kinds of VTI ***,the method can provide reliable dispersion curves for both theoretical analysis and anisotropic parameters inversion in VTI formations.

关键词： Dispersion equation Scholte wave velocity Acoustic properties Transverse isotropy Thomsen anisotropic parameters inversion

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Electrical conductivity models in saturated porous media: A review

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EARTH-SCIENCE REVIEWS 2017年 171卷 419-433页

作者： Cai, Jianchao Wei, Wei Hu, Xiangyun Wood, David A. China Univ Geosci Inst Geophys & Geomat Hubei Subsurface Multi Scale Imaging Key Lab Wuhan 430074 Hubei Peoples R China DWA Energy Ltd Lincoln England

Electrical transport properties of saturated porous media, such as soils, rocks and fractured networks, typically composed of a non-conductive solid matrix and a conductive brine in the pore space, have numerous applications in reservoir engineering and petrophysics. One of the widely used electrical conductivity models is the empirical Archie's law that has a practical application in well-log interpretation of reservoir rocks. The Archie equation does not take into account the contributions of clay minerals, isolated porosity, heterogeneity in grains and pores and their distributions, as well as anisotropy. In the literature, either some modifications were presented to apply Archie's law to tight and clay-rich reservoirs or more modern models were developed to describe electrical conductivity in such reservoirs. In the former, a number of empirically derived parameters were proposed, which typically vary from one reservoir to another. In the latter, theoretical improvements by including detailed characteristics of pore space morphology led to developing more complex electrical conductivity models. Such models enabled us to address the electrical properties in a wider range of potential reservoir rocks through theoretical parameters related to key reservoir-defining petrophysical properties. This paper presents a review of the electrical conductivity models developed using fractal, percolation and effective medium theories. key results obtained by comparing experiential and theoretical models with experiments/simulations, as well as advantages and drawbacks of each model are analyzed. Approaches to obtaining more reasonable electrical conductivity models are discussed. Experiments suggest more complex relationships between electrical conductivity and porosity than experiential models, particularly in low-porosity formations. However, the available theoretical models combined with simulations do provide insight to how microscale physics affects macroscale electrical

关键词： Electrical conductivity Porous media Fractal model Percolation theory Effective medium approximation Pore-network model

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Fast forward modeling of gravity anomalies for two-dimensional bodies of arbitrary shape and density distribution

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Applied Geophysics 2020年第5期17卷 776-783,902,903页

作者： Chen Xin Chen Long-Wei Luo Tian-Ya Xiong Bin Guangxi Key Laboratory of Exploration for Hidden Metallic Ore Deposits College of Earth SciencesGuilin University of TechnologyGuilin 541006China Hubei Subsurface Multi-scale Imaging Key Laboratory Institute of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074China

A fast and high precision spatial domain algorithm is presented for forward modeling of two-dimensional(2D)body gravity anomalies of arbitrary shape and density *** new algorithm takes advantage of the convolution properties of the expression for 2D gravity anomalies,uses a rectangular cell as a grid subdivision unit,and then 2D bodies with irregular cross-sections are approximated by a combination of 2D bodies with a rectangular cross *** closed-form expression is used to calculate the gravitational anomalies of the combination of 2D bodies with a rectangular cross *** improve computing effi ciency,the new algorithm uses a fast algorithm for the implementation of the Toeplitz matrix and vector *** synthetic 2D models with rectangular and circular cross-sections and constant and variable densities are designed to evaluate the computational accuracy and speed of the new *** experiment results show that the computation costs less than 6 s for a grid subdivision with 10000×10000 *** to the traditional forward modeling methods,the proposed method significantly improved computational effi ciency while guaranteeing computational accuracy.

关键词： two-dimensional bodies gravity anomalies forward modeling Toeplitz matrix

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