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Inversion of explosive source land seismic data to determine source signature parameters Geophys. Prospect. (IF 1.556) Pub Date : 2021-01-27 Anton Ziolkowski
In seismic land exploration, where terrain conditions limit the use of vibrator sources, explosive sources are the preferred choice, and in situations where low frequency energy is essential, explosive is the preferred source, because it contains energy down to D.C. (0 Hz). I present a new method to estimate the source time functions of explosion source seismic data, using a modified acquisition method
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Sensitivity and depth of investigation from Monte Carlo ensemble statistics Geophys. Prospect. (IF 1.556) Pub Date : 2020-12-30 Christin Bobe; Johannes Keller; Ellen Van De Vijver
For many geophysical measurements, such as direct current or electromagnetic induction methods, information fades away with depth. This has to be taken into account when interpreting models estimated from such measurements. For that reason, a measurement sensitivity analysis and determining the depth of investigation are standard steps during geophysical data processing. In deterministic gradient‐based
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Working mechanism and experimental study of electromagnetic measurement while drilling systems based on a relay station Geophys. Prospect. (IF 1.556) Pub Date : 2021-01-25 Chunhua Lu; Rongjing Wang; Huibin Zhao; Tao Zhang
Electromagnetic measurement while drilling (EM‐MWD) systems transmit downhole data via an information channel composed of a drill string and formation; the formation has a strong attenuation effect on the signal. Signal attenuation during EM wave transmission through the formation limits the well depth at which this technique can be applied. This paper discusses several commonly used methods to improve
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The Frequency Exponent of Artificial Sandstone's Complex Resistivity Spectrum Geophys. Prospect. (IF 1.556) Pub Date : 2021-01-25 Jiang Jia; Shizhen Ke; Reza Rezaee; Junjian Li; Feng Wu
The complex resistivity spectra of 16 artificial sandstone samples with different physical property at different water and solution saturations were measured and fitted with the Cole‐Cole model in the frequency band of 40 Hz to 110 MHz. The frequency exponent in the model indicates the ideal degree of the sample's capacitive property. The experiment result shows that the frequency exponents of the
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Prestack seismic data interpolation and enhancement with CRS‐based migration and demigration Geophys. Prospect. (IF 1.556) Pub Date : 2021-01-25 German Garabito
The standard common‐reflection‐surface (CRS) stacking method simulates from multi‐coverage prestack data high‐quality zero‐offset stacked data and, as by‐products, provides three kinematic wavefield attributes in two dimensions that can be applied to solve reflection seismic problems. One of the most significant applications of those attributes is for interpolation and enhancement of prestack data
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Seismic noise attenuation by signal reconstruction: an unsupervised machine learning approach Geophys. Prospect. (IF 1.556) Pub Date : 2021-01-22 Yang Gao; Pingqi Zhao; Guofa Li; Hao Li
Random noise attenuation is an essential step in seismic data processing for improving seismic data quality and signal‐to‐noise ratio (S/N). We adopt an unsupervised machine learning approach to attenuate random noise via signal reconstruction strategy. This approach can be accomplished in the following steps: Firstly, we randomly mute a part of the input data of the neural network according to a certain
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On the equivalence of the conductivity and resistivity equations in the interpretation of induced polarization data Geophys. Prospect. (IF 1.556) Pub Date : 2020-12-29 Nikolai O. Kozhevnikov; Evgeny Y. Antonov
There are several models accounting for the induced polarization phenomenon in terms of complex, frequency‐dependent conductivity σ or resistivity ρ = 1/σ. The most popular ones are the Cole–Cole conductivity and Pelton resistivity models. Each model includes four parameters: resistivity ρ (or its inverse, conductivity σ), chargeability m, relaxation time τ and frequency dependence c. Some authors
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Dispersion of flexural waves in a borehole with a tensile fracture in an anisotropic stress environment Geophys. Prospect. (IF 1.556) Pub Date : 2021-01-18 Kosuke Kayama; Hitoshi Mikada; Junichi Takekawa
The effect of tensile fracture in a vertical borehole under anisotropic horizontal stress conditions is numerically investigated in terms of the dispersion of flexural wave generated in dipole sonic logging. Our three‐dimensional model comprises a borehole filled with water and a tensile fracture intersecting the borehole in the borehole axial direction. Two shear waves are excited individually to
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Kirchhoff pre‐stack depth scalar migration in a simple triclinic velocity model for three‐component P, S1, S2 and converted waves Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-10 Václav Bucha
Migration of multi‐component elastic data in anisotropic models is difficult and has not been reasonably addressed. Thus we test three‐dimensional ray‐based Kirchhoff pre‐stack depth scalar migration and calculate migrated sections in a simple anisotropic velocity model. We generate ray‐theory seismograms for separate phases of reflected P, S1, S2 and converted waves. The velocity model is composed
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Seismic data interpolation using deep learning with generative adversarial networks Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-29 Harpreet Kaur; Nam Pham; Sergey Fomel
We propose an algorithm for seismic trace interpolation using generative adversarial networks, a type of deep neural network. The method extracts feature vectors from the training data using self‐learning and does not require any pre‐processing to create the training labels. The algorithm also does not make any prior explicit assumptions about linearity of seismic events or sparsity of the data, which
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Unified elimination of 1D acoustic multiple reflection Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-18 Evert Slob; Lele Zhang
Migration, velocity and amplitude analysis are the employed processing steps to find the desired subsurface information from seismic reflection data. The presence of free‐surface and internal multiples can mask the primary reflections for which many processing methods are built. The ability to separate primary from multiple reflections is desirable. Connecting Marchenko theory with classical one‐dimensional
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Elastic wave‐mode separation in 2D transversely isotropic media using optical flow Geophys. Prospect. (IF 1.556) Pub Date : 2020-12-03 Xiaoyi Wang; Yongming Lu; Jianfeng Zhang
Wave‐mode separation is a critical step in anisotropic elastic‐wave imaging. To avoid high computational costs and additional corrections, we apply a separation formula in the space domain that projects Cartesian components of the elastic wavefield onto the polarization vectors in the orthogonal direction. By solving the Christoffel equation, we implement the conversion from the phase velocity direction
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Deep learning assisted well log inversion for fracture identification Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-18 Miao Tian; Bingtao Li; Huaimin Xu; Dezhi Yan; Yining Gao; Xiaozheng Lang
Manual fracture identification methods based on cores and image logging pseudo‐pictures are limited by the expense and the amount of data. In this paper, we propose an integrated workflow, which takes the fracture identification as an end‐to‐end project, to combine the boundary detection and the deep learning classification to recognize fractured zones with accurate locations and reasonable thickness
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Subsurface structures of the Xiaorequanzi deposit, NW China: new insights from gravity, magnetic and electromagnetic data Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-10 An Shaole; Zhang Zhixin; Zhou Kefa; Wang Jinlin
The Xiaorequanzi copper–zinc deposit, located in the eastern Tianshan, is considered as a medium‐sized polymetallic deposit in Xinjiang, NW China. Understanding the structural framework and delineating the location of intrusions as well as the distribution of ore‐controlling strata in this mining area are vital for identifying new potential exploration areas. This paper aims to provide new information
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Denoising of magnetotelluric data using K‐SVD dictionary training Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-27 Jin Li; Yiqun Peng; Jingtian Tang; Yong Li
Magnetotelluric is one of the mainstream exploration geophysical methods, which plays a vital role in studying deep geological structures and finding deep hidden blind ore bodies. The seriousness of human electromagnetic noise causes a large number of abnormal waveforms in the time series of measured magnetotelluric data, and the data can no longer objectively reflect the underground electrical distribution
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Improved controlled source audio‐frequency magnetotelluric method apparent resistivity pseudo‐sections based on the frequency and frequency–spatial gradients of electromagnetic fields Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-27 Ming Zhang; Colin G. Farquharson; Changsheng Liu
Although most electromagnetic data can be inverted to actual resistivity, ways of quickly getting a real‐time interpretation of a data set are still valuable. Such methods are useful when we are testing instrumentation or assessing data quality during a survey, or when we need to get a general understanding of the geological structure during a field survey. Apparent resistivity is a good way to satisfy
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Recovering sparse models in 3D potential‐field inversion without bound dependence or staircasing problems using a mixed Lp norm regularization Geophys. Prospect. (IF 1.556) Pub Date : 2020-12-17 Jiajia Sun; Xiaolong Wei
Sparse inversions have proven to be useful for interpreting potential‐field data because the recovered models are characterized by sharp boundaries, compact features and elevated values, compared with conventional smoothness‐based inversion results. However, several open problems remain to be addressed, including the bound dependence and staircasing problems. The former results in recovered anomalous
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Reconstruction of seismic signals using S‐transform ridges Geophys. Prospect. (IF 1.556) Pub Date : 2021-01-12 Aleksander S. Serdyukov; Anton V. Azarov; Aleksander V. Yablokov; Tatiana V. Shilova; Valery D. Baranov
We have addressed the problem of seismic data frequency‐time filtration based on the S‐transform. The S‐transform provides frequency‐dependent resolution while maintaining a direct relationship with the Fourier spectrum and has been widely used in different seismic data‐processing applications. The standard S‐transform filtration method is based on its invertibility. In a sense of time localization
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Angle domain common image gathers from reverse time migration by combining the Poynting vector with directional decomposition Geophys. Prospect. (IF 1.556) Pub Date : 2020-12-25 Feipeng Li; Jinghuai Gao; Zhaoqi Gao; Chuang Li; Wei Zhang; Wenbo Sun
Angle domain common image gathers are crucial for seismic applications such as the migration velocity analysis and amplitude variation with angle analysis. Angle domain common image gathers are the gather of reflection coefficients when seismic waves incident at different angles on the same image point. The curvature of gathers can be used to update the migration velocity model. The amplitude variation
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A workflow for multimineralogic carbonate rock physics modelling in a Bayesian framework: Brazilian pre‐salt reservoir case study Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-30 Jonatan Dias; Jorge L. Lopez; Raquel Velloso; Fabio Perosi
We develop a workflow to estimate elastic attributes ( V p and V s ) of Pre‐Salt carbonate reservoirs using the Xu and Payne rock physics model in a depth‐variant multimineralogic fashion and apply it to one calibration and four extrapolation wells in a field in the Brazilian Santos Basin. Some of the parameters were stochastically simulated in a Bayesian framework to handle the model non‐uniqueness
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Simultaneous‐source deblending using adaptive coherence‐constrained dictionary learning and sparse approximation Geophys. Prospect. (IF 1.556) Pub Date : 2020-12-31 E. Isaac Evinemi; Weijian Mao
The dictionary learning and sparse approximation method using the K ‐ Singular Value Decomposition algorithm rely on the knowledge of the sparsity or noise variance as a constraint when it is used for data denoising. However, the determination of the sparsity or noise variance of seismic data can be tricky and sometimes unknown, especially in seismic field data. Thus, where the cardinality or the noise
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Sparsity‐promoting least‐squares reverse time migration via preconditioned Bregmanized operator splitting Geophys. Prospect. (IF 1.556) Pub Date : 2020-12-30 Toktam Zand; Hamid Reza Siahkoohi
Nowadays the least‐squares reverse time migration has become the most used migration method because of its accuracy in amplitude recovery and high resolution imaging, specifically its priority to image the beneath of structural domes such as salt domes. However, errors in migration velocity model, inadequate physics of modeling/migration, and too sparse data decrease the quality of the migrated image
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Seismic dispersion and attenuation in Mancos shale – laboratory measurements Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-16 V. Mikhaltsevitch; M. Lebedev; M. Pervukhina; B. Gurevich
We present the results of a low‐frequency study of Mancos shale, where we first elaborate a stress–strain methodology of laboratory low‐frequency experiments to estimate the elastic moduli of shales, and then apply this methodology to investigate the influence of partial water saturation on the elastic and anelastic parameters, velocities and P‐wave anisotropy of Mancos shale. We also analyse the applicability
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PATCHUNET: A fully‐unsupervised and highly‐generalized deep learning approach for random noise suppression Geophys. Prospect. (IF 1.556) Pub Date : 2020-12-19 Omar M. Saad; Yangkang Chen
We develop a deep learning algorithm (PATCHUNET) to suppress random noise and preserve the coherent seismic signal. The input data is divided into several patches, each patch is encoded to extract the meaningful features. Following this, the extracted features are decompressed to retrieve the seismic signal. Skip connections are used between the encoder and decoder parts, allowing the PATCHUNET to
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Eigenrays in 3D heterogeneous anisotropic media, Part I: Kinematics Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-12 Zvi Koren; Igor Ravve
We present a new ray bending approach, referred to as the Eigenray method, for solving two‐point boundary‐value kinematic and dynamic ray tracing problems in 3D smooth heterogeneous general anisotropic elastic media. The proposed Eigenray method is aimed to provide reliable stationary ray path solutions and their dynamic characteristics, in cases where conventional initial‐value ray shooting methods
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Eigenrays in 3D heterogeneous anisotropic media, Part II: Dynamics Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-11 Igor Ravve; Zvi Koren
This paper is the second in a sequel of two papers and dedicated to the computation of paraxial rays and dynamic characteristics along the stationary rays obtained in the first paper. We start by formulating the linear, second‐order, Jacobi dynamic ray tracing equation. We then apply a similar finite‐element solver, as used for the kinematic ray tracing, to compute the dynamic characteristics between
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Mapping of underground cavities by the passive seismic standing waves method: the case study of Barsukovskaya cave (Novosibirsk region, Russia) Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-29 Konstantin V. Fedin; Yury I. Kolesnikov; Luckymore Ngomayezwe
This article presents the results of mapping a karst cave by the passive seismic standing waves method. Barsukovskaya cave is located about 100 km southeast of the city of Novosibirsk (Russia). The total length of the cave's passages and grottoes is estimated at about 200 m, the maximum depth from the earth's surface is about 19 m. The method for studying underground cavities used is based on the effect
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Anisotropic attenuation of stratified viscoelastic media Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-08 Jing Zeng; Alexey Stovas; Handong Huang
An important cause of seismic anisotropic attenuation is the interbedding of thin viscoelastic layers. However, much less attention has been devoted to layer‐induced anisotropic attenuation. Here, we derive a group of unified weighted average forms for effective attenuation from a binary isotropic, transversely isotropic‐ and orthorhombic‐layered medium in the zero‐frequency limit by using the Backus
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Seismic dispersion and attenuation in layered porous rocks with fractures of varying orientations Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-03 Denghui Xu; Tongcheng Han; Li‐Yun Fu
Wave‐induced fluid flow plays an important role in affecting the seismic dispersion and attenuation of fractured porous rocks. While numerous theoretical models have been proposed for the seismic dispersion and attenuation in fractured porous rocks, most of them neglect the wave‐induced fluid flow resulting from the background anisotropy (e.g. the interlayer fluid flow between different layers) that
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Seismic time–frequency analysis as a robust method to estimate the fluid saturation: A case study of carbonates reservoir, Iran Geophys. Prospect. (IF 1.556) Pub Date : 2020-11-03 Javad Jamali; Abdolrahim Javaherian
The propagation of seismic waves through a saturated reservoir compresses the fluid in the pore spaces. During this transition, parts of seismic energy would be attenuated because of intrinsic absorption. Rock physics models make the bridge between the seismic properties and petrophysical reality in the earth. Attenuation is one of the significant seismic attributes used to describe the fluid behaviour
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Dependence of borehole shear‐horizontal‐wave seismoelectric response on soil textures Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-04 Weihao Wang; Zhiwen Cui; Jinxia Liu; Tribikram Kundu
The phenomenon of acoustic waves inducing electric fields in porous media is called the seismoelectric effect. Earlier investigators proposed the usage of seismoelectric effect for well logging. Soil texture has a strong influence on the coupled wave fields during shallow surface explorations. In this article, we study the borehole pure shear‐horizontal wave and the coupling transverse‐electric field
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Water‐flooding and consolidation of reservoir chalk – effect on porosity and Biot's coefficient Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-29 Tobias B. Gram; Frederik P. Ditlevsen; Klaus Mosegaard; Ida L. Fabricius
Improved oil recovery from chalk reservoirs by water‐flooding may cause mechanical weakening and change in elasticity. Confined compressive strength testing of chalk from a North Sea reservoir was done in water‐saturated and oil‐saturated conditions. During testing, elastic wave velocities were sampled by ultrasonic transducers, so that subsequently Biot's coefficient could be modelled. The porosity
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Biot effective stress parameter in poroelastic anisotropic media: Static and dynamic case Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-29 Sharif M. Morshed; Evgeny M. Chesnokov; Alexandra A. Vikhoreva
Stress, rock microstructure and frequency are the three key factors that influence the velocities of elastic waves and, hence, are sensitive to the Biot effective stress parameter (α) in porous rocks. The effective stress in an isotropic poroelastic medium relates to applied pressure and pore pressure, with the Biot parameter (α) as a scaling factor of the pore pressure. This paper provides an independent
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From cradle to grave: how burial history controls the rock‐physics properties of quartzose sandstones Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-03 Ivan Lehocki; Per Avseth
Rock‐physics properties of sands and sandstones are strongly affected by geological processes of the past, including deposition, compaction and exhumation. By honouring these geological processes, the rock‐physics modelling will be more predictive in areas with limited well control. This study performs rock‐physics modelling constrained by a given geological history, starting from deposition to mechanical
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Elastic properties of a reservoir sandstone: a broadband inter‐laboratory benchmarking exercise Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-30 Abdulwaheed Ògúnsàmì; Ian Jackson; Jan V.M. Borgomano; Jérôme Fortin; Hasan Sidi; Andre Gerhardt; Boris Gurevich; Vassili Mikhaltsevitch; Maxim Lebedev
Low‐frequency forced‐oscillation methods applied to a reservoir sandstone allowed determination of the Young's modulus and Poisson's ratio (from axial loading), bulk modulus (by oscillation of the confining pressure) and shear modulus (from torsional‐forced oscillations) for comparison with conventional ultrasonic data. All tests were performed on a common sandstone core sample from an oil reservoir
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The impact of seismic inversion methodology on rock property prediction Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-21 Mariana Martinho; Timothy Tylor‐Jones; Leonardo Azevedo
Seismic inversion is a central step within the seismic reservoir characterization workflow. In seismic inversion, seismic amplitudes are inverted to predict the spatial distribution of the subsurface elastic properties. In subsequent steps of the geomodelling workflow, the inverted models are then converted into rock properties and facies. The methodology to perform the seismic inversion does have
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Order‐controlled closed‐loop focal beams and resolution comparison of primary and multiple reflections for seismic acquisition geometries Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-13 Wei Wei; Gerrit Blacquière
Focal beam analysis has built a bridge between the acquisition parameters on the surface and the image quality of underground targets. However, as a practical matter, it is still difficult to answer how to choose a proper acquisition geometry according to the complexity of medium, especially considering the contradictory effects of multiple reflections on spatial resolution as they can be considered
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Windowless Q‐factor tomography by the instantaneous frequency Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-16 A. Vesnaver; G. Böhm; P. Cance; M. Dal Cin; D. Gei
The estimation of the Q factor of rocks by seismic surveys is a powerful tool for reservoir characterization, as it helps detecting possible fractures and saturating fluids. Seismic tomography allows building 3D macro‐models for the Q factor, using methods as the spectral ratio and the frequency shift. Both these algorithms require windowing the seismic signal accurately in the time domain; however
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Review Paper: Methods of measurement for 4D seismic post‐stack time shifts Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-14 Colin MacBeth; Hamed Amini; Saeed Izadian
The estimation of time‐lapse time shifts between two, or several, repeated seismic surveys has become increasingly popular over the past eighteen years. These time shifts are a reliable and informative seismic attribute that can relate to reservoir production. Correction for these time shifts or the underlying velocity perturbations and/or subsurface displacement in an imaging sense also permits accurate
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Time‐domain sparsity promoting least‐squares reverse time migration with source estimation Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-18 Mengmeng Yang; Zhilong Fang; Philipp Witte; Felix J. Herrmann
Least‐squares reverse‐time migration is well known for its capability to generate artefact‐free true‐amplitude subsurface images through fitting observed data in the least‐squares sense. However, when applied to realistic imaging problems, this approach is faced with issues related to overfitting and excessive computational costs induced by many wave‐equation solves. The fact that the source function
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2D and 3D amplitude‐preserving elastic reverse time migration based on the vector‐decomposed P‐ and S‐wave records Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-27 Wei Zhang; Jinghuai Gao; Zhaoqi Gao; Ying Shi
The elastic reverse time migration approach based on the vector‐wavefield decomposition generally uses the scalar product imaging condition to image the multicomponent seismic data. However, the resulting images contain the crosstalk artefacts and the polarity reversal problems, which are caused by the nonphysical wave modes and the angle‐dependent reduction of image amplitudes, respectively. To overcome
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Combining discrete cosine transform and convolutional neural networks to speed up the Hamiltonian Monte Carlo inversion of pre‐stack seismic data Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-21 Mattia Aleardi
Markov chain Monte Carlo algorithms are commonly employed for accurate uncertainty appraisals in non‐linear inverse problems. The downside of these algorithms is the considerable number of samples needed to achieve reliable posterior estimations, especially in high‐dimensional model spaces. To overcome this issue, the Hamiltonian Monte Carlo algorithm has recently been introduced to solve geophysical
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Pure P‐ and S‐wave equations in transversely isotropic media Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-21 Alexey Stovas; Tariq Alkhalifah; Umair bin Waheed
Pure‐mode wave propagation is important for applications ranging from imaging to avoiding parameter tradeoff in waveform inversion. Although seismic anisotropy is an elastic phenomenon, pseudo‐acoustic approximations are routinely used to avoid the high computational cost and difficulty in decoupling wave modes to obtain interpretable seismic images. However, such approximations may result in inaccuracies
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Convolutional neural networks for automated microseismic detection in downhole distributed acoustic sensing data and comparison to a surface geophone array Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-28 Gary Binder; Ali Tura
Distributed acoustic sensing is a growing technology that enables affordable downhole recording of strain wavefields from microseismic events with spatial sampling down to ∼1 m. Exploiting this high spatial information density motivates different detection approaches than typically used for downhole geophones. A new machine learning method using convolutional neural networks is described that operates
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Seismic signal enhancement based on the low‐rank methods Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-28 Min Bai; Guangtan Huang; Hang Wang; Yangkang Chen
Based on the fact that the Hankel matrix constructed by noise‐free seismic data is low‐rank, low‐rank approximation (or rank‐reduction) methods have been widely used for removing noise from seismic data. Due to the linear‐event assumption of the traditional low‐rank approximation method, it is difficult to define a rank that optimally separates the data subspace into signal and noise subspaces. For
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Experimental study on frequency‐dependent elastic properties of weakly consolidated marine sandstone: effects of partial saturation Geophys. Prospect. (IF 1.556) Pub Date : 2020-09-17 Hui Li; Luanxiao Zhao; De‐hua Han; Jinghuai Gao; Hemin Yuan; Yirong Wang
Investigating seismic dispersion and attenuation characteristics of loosely compacted marine sandstone is essential in reconciling different geophysical measurements (surface seismic, well logging and ultrasonic) for better characterization of a shallow marine sandstone reservoir. We have experimented with a typical high‐porosity and high‐permeability sandstone sample, extracted from the Paleogene
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Three‐dimensional electrical structure of the northwestern margin of the Karamay region, China, revealed by magnetotelluric data Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-28 Yixin Ye; Shengping Gong; Hui Yu; Zhibing Feng; Wenyu Liu
In order to investigate the three‐dimensional structures of intrusive granite and the deep structure of the Darbut fault in the northwestern margin of the Karamay region, western Junggar Basin, China, new magnetotelluric data were collected along six profiles across the Darbut fault. The magnetotelluric data were processed using a robust estimation technique to obtain the magnetotelluric impedance
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Stress prediction and evaluation approach based on azimuthal amplitude‐versus‐offset inversion of unconventional reservoirs Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-05 Bingyi Du; Guangzhi Zhang; Jing Zhang; Jianhu Gao; Xueshan Yong; Wuyang Yang; Ren Jiang; Shujiang Wang; Hailiang Li; Enli Wang
A novel approach of unconventional reservoir stress evaluation is proposed to enhance the accuracy of fracture development prediction. Differential horizontal stress ratio can reflect the stress characteristic of fractured reservoir. To calculate the differential horizontal stress ratio more intuitionistic and simpler, we re‐derive its formula with Poisson's ratio and fracture density. Meanwhile, a
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Optimized experimental design for seismic full waveform inversion: A computationally efficient method including a flexible implementation of acquisition costs Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-02 Valérie Krampe; Pascal Edme; Hansruedi Maurer
Optimized experimental design aims at reducing the cost of a seismic survey by identifying the optimal locations and amounts of sources and receivers. While the acquisition design in the context of seismic imaging applies criteria like fold, offset and spatial sampling, different attributes such as the sensitivity kernels are more relevant for seismic full waveform inversion. An ideal measure to quantify
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Calculating complex‐valued P‐wave first‐arrival traveltimes in attenuative vertical transversely isotropic media with an irregular surface Geophys. Prospect. (IF 1.556) Pub Date : 2020-10-01 Mengxiu Wang; Jingyi Chen; Zhencong Zhao; Wenyi Hu
The complex‐valued first‐arrival traveltime can be used to describe the properties of both velocity and attenuation as seismic waves propagate in attenuative elastic media. The real part of the complex‐valued traveltime corresponds to phase arrival and the imaginary part is associated with the amplitude decay due to energy absorption. The eikonal equation for attenuative vertical transversely isotropic
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Effects of petrophysical parameters on attenuation and dispersion of seismic waves in the simplified poroelastic theory: Comparison between the Biot's theory and viscosity‐extended theory Geophys. Prospect. (IF 1.556) Pub Date : 2020-09-30 Haixia Zhao; Bangyu Wu; Jinghuai Gao
The simplified macro‐equations of porous elastic media are presented based on Hickey's theory upon ignoring effects of thermomechanical coupling and fluctuations of porosity and density induced by passing waves. The macro‐equations with definite physical parameters predict two types of compressional waves (P wave) and two types of shear waves (S wave). The first types of P and S waves, similar to the
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Time evolution of the first‐order linear acoustic/elastic wave equation using Lie product formula and Taylor expansion Geophys. Prospect. (IF 1.556) Pub Date : 2020-09-29 Edvaldo S. Araujo; Reynam C. Pestana
We propose a new numerical solution to the first‐order linear acoustic/elastic wave equation. This numerical solution is based on the analytic solution of the linear acoustic/elastic wave equation and uses the Lie product formula, where the time evolution operator of the analytic solution is written as a product of exponential matrices where each exponential matrix term is then approximated by Taylor
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Passive seismic data primary estimation and noise removal via focal‐denoising closed‐loop surface‐related multiple elimination based on 3D L1‐norm sparse inversion Geophys. Prospect. (IF 1.556) Pub Date : 2020-09-29 Tiexing Wang; Deli Wang; Jing Sun; Bin Hu
Passive seismic has recently attracted a great deal of attention because non‐artificial source is used in subsurface imaging. The utilization of passive source is low cost compared with artificial‐source exploration. In general, constructing virtual shot gathers by using cross‐correlation is a preliminary step in passive seismic data processing, which provides the basis for applying conventional seismic
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Erratic noise suppression using iterative structure‐oriented space‐varying median filtering with sparsity constraint Geophys. Prospect. (IF 1.556) Pub Date : 2020-09-24 Guangtan Huang; Min Bai; Qiang Zhao; Wei Chen; Yangkang Chen
Erratic noise often has high amplitudes and a non‐Gaussian distribution. Least‐squares–based approaches therefore are not optimal. This can be handled better with non–least‐squares approaches, for example based on Huber norm which is computationally expensive. An alternative method has been published which involves transforming the data with erratic noise to pseudodata that have Gaussian distributed
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Geometrical characteristics of phase and group velocity surfaces in anisotropic media Geophys. Prospect. (IF 1.556) Pub Date : 2020-09-11 Alexey Stovas; Yuriy Roganov; Vyacheslav Roganov
The phase and group velocity surfaces are essential for wave propagation in anisotropic media. These surfaces have certain features that, especially, for shear waves result in complications for modelling and inversion of recorded wavefields. To analyse wave propagation in an anisotropic model, it is important to identify these features in both the phase and group domains. We propose few characteristics
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Two‐dimensional dictionary learning for suppressing random seismic noise Geophys. Prospect. (IF 1.556) Pub Date : 2020-09-01 Kunhong Li; Zhining Liu; Bin She; Hanpeng Cai; Yaojun Wang; Guangmin Hu
Dictionary learning is a successful method for random seismic noise attenuation that has been proven by some scholars. Dictionary learning–based techniques aim to learn a set of common bases called dictionaries from given noised seismic data. Then, the denoising process will be performed by assuming a sparse representation on each small local patch of the seismic data over the learned dictionary. The
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Pre‐stack seismic inversion based on ‐norm regularized logarithmic absolute misfit function Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-23 Guangtan Huang, Xiaohong Chen, Cong Luo, Yangkang Chen
Ill‐posedness is one of the most common and intractable issues that arise when solving geophysical inverse problems. Ill‐posedness could be induced by various factors such as noise, band‐limited intrinsic property of seismic data and inappropriate forward operators. Regularization has been proven to be an effective method widely accepted for mitigating the adverse effects of ill‐posedness. Aiming to
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The tunnel seismic advance prediction method with wide illumination and a high signal‐to‐noise ratio Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-12 Xinglin Lu, Xian Liao, Yao Wang, Guimei Wang, Zhihong Fu, HengMing Tai
Tunnel seismic prediction is widely used in the field of tunnel seismic advance detection. The illumination of the target and the signal‐to‐noise ratio of the data are two key factors affecting the precision of data interpretation. Current seismic prospecting has shortcomings on sites: (1) The lighting shots are solely towards one side of the tunnel wall, (2) the geophones are placed far away from
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Angle‐domain imaging of relative impedance perturbation Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-07 Yanan Liu, Shengchang Chen, Guoxin Chen, Feng Wang, Zhiwei Gu
Impedance is a physical parameter that plays an important role in seismic data processing and interpretation. A relative impedance perturbation (the ratio of the impedance perturbation and the impedance for the background models) imaging method in depth domain based on the reflection wave equation is proposed. Under the small perturbation assumption, primary wave and high‐frequency approximation condition
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Erratum Geophys. Prospect. (IF 1.556) Pub Date : 2020-08-06
In Tohti et al . (2020), there is a conflict in the use of symbol for porosity in the paragraph after equation (11) with the symbol used for electrical potential: The symbol for porosity should be Φ and the corrected text is as follows: The errors have been corrected in the online version of the article.
Contents have been reproduced by permission of the publishers.