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Two exact first-order k-space formulations for low-rank viscoacoustic wave propagation on staggered grids

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Petroleum Science 2023年第3期20卷 1521-1531页

作者： Hong-Yu Zhou Yang Liu Jing Wang China Universityof Petroleum(Bejing) State Key Laboratory of Petroleum Resources and Prospecting and CNPC Key Laboratory of Geophysical ProspectingBeijing102249China China University of Petroleum(Bejing) Karamay CampusKaramayXinjiang834000China

Wave propagation in the viscoacoustic media is physically dispersive and *** excluding the numerical dispersion error from the physical dispersion in the viscoacoustic wave simu-lation is indispensable to understanding the intrinsic property of the wave propagation in attenuated media for the petroleum exploration *** recent years,a viscoacoustic wave equation char-acterized by fractional Laplacian gains wide attention in geophysical ***,the first-order form of the viscoacoustic wave equation,often solved by the conventional staggered-grid pseu-dospectral method,suffers from the numerical dispersion error in time due to the low-order finite-difference *** is challenging to completely eliminate the error because the viscoacoustic wave equation contains two temporal derivatives,which stem from the time stepping and the amplitude attenuation terms,*** tackle the issue,we derive two exact first-order k-space viscoacoustic formulations that can fully exclude the numerical error from the physical *** the homoge-neous case,two formulations agree with the viscoacoustic analytical solution very well and have the same *** the heterogeneous case,our second k-space formulation is more efficient than the first one because the second formulation significantly reduces the number of the wavenumber-space mixed-domain operators,which are the expensive part of the viscoacoustic k-space ***-merical cases validate that the two first-order k-space formulations are effective and efficient alternatives to the current staggered-grid pseudospectral formulation for the viscoacoustic wave simulation.

关键词： Viscoacoustic K-space Staggered-grid Low-rank

Effect of regularization parameters on geophysical reconstruction

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Petroleum Science 2009年第2期6卷 119-126页

作者： Zhou Hui Wang Zhaolei Qiu Dongling Li Guofa Shen Jinsong State key laboratory of Petroleum Resource and prospecting China University of Petroleum Beijing 102249 China key laboratory of CNPC geophysical prospecting China University of Petroleum Beijing 102249 China Research Institute Bureau of Geophysical Prospecting Hebei 072751 China China University of Petroleum Beijing 102249 China

In this paper we discuss the edge-preserving regularization method in the reconstruction of physical parameters from geophysical data such as seismic and ground-penetrating radar data. In the regularization method a potential function of model parameters and its corresponding functions are introduced. This method is stable and able to preserve boundaries, and protect resolution. The effect of regularization depends to a great extent on the suitable choice of regularization parameters. The influence of the edge-preserving parameters on the reconstruction results is investigated and the relationship between the regularization parameters and the error of data is described.

关键词： geophysical data inversion error of data regularization regularization parameters

Model-data-driven P-wave impedance inversion using ResNets and the normalized zero-lag cross-correlation objective function

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Petroleum Science 2022年第6期19卷 2711-2719页

作者： Yu-Hang Sun Yang Liu CNPC key laboratory of geophysical prospecting and State key laboratory of Petroleum Resources and prospecting China University of Petroleum(Beijing)Beijing102249China China University of Petroleum(Beijing) Karamay CampusKaramayXinjiang834000China

Model-driven and data-driven inversions are two prominent methods for obtaining P-wave impedance,which is significant in reservoir description and *** on proper initial models,most model-driven methods primarily use the limited frequency bandwidth information of seismic data and can invert P-wave impedance with high accuracy,but not high *** data-driven methods mainly employ the information from well-log data and can provide high-accuracy and highresolution P-wave impedance owing to the superior nonlinear curve fitting capacity of neural ***,these methods require a significant number of training samples,which are frequently *** obtain P-wave impedance with both high accuracy and high resolution,we propose a model-data-driven inversion method using Res Nets and the normalized zero-lag cross-correlation objective function which is effective for avoiding local minima and suppressing random *** using initial models and training samples,the proposed model-data-driven method can invert P-wave impedance with satisfactory accuracy and *** on synthetic and field data demonstrate the proposed method’s efficacy and practicability.

关键词： Model-data-driven P-wave impedance inversion Res Nets Zero-lag cross-correlation

Enhancing the resolution of seismic data based on the generalized S-transform

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Petroleum Science 2009年第2期6卷 153-157页

作者： Tian Jianhua Song Wei Yang Feizhou State key laboratory of Petroleum Resource and prospecting China University of Petroleum Beijing 102249 China key laboratory of CNPC geophysical prospecting China University of Petroleum Beijing 102249 China

In this paper, we analyze the seismic signal in the time-frequency domain using the generalized S-transform combined with spectrum modeling. Without assuming that the reflection coefficients are random white noise as in the conventional resolution-enhanced techniques, the wavelet which changes with time and frequency was simulated and eliminated. After using the inverse S-transform for the processed instantaneous spectrum, the signal in the time domain was obtained again with a more balanced spectrum and broader frequency band. The quality of seismic data was improved without additional noise.

关键词： Time-frequency domain generalized S-transform spectrum modeling instantaneous spectrum balanced spectrum

Automatic fracture–vug identification and extraction from electric imaging logging data based on path morphology

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Petroleum Science 2019年第1期16卷 58-76页

作者： Xi-Ning Li Jin-Song Shen Wu-Yang Yang Zhen-Ling Li State key laboratory of Petroleum Resources and prospecting China University of Petroleum CNPC key laboratory of geophysical prospecting China University of Petroleum North-west Division of Exploration and Production Research Institute CNPC Huabei Division of China Petroleum Logging Corporation

We present a path morphology method to separate total rock pore space into matrix, fractures and vugs and derive their pore structure spectrum. Thus, we can achieve fine pore evaluation in fracture–vug reservoirs based on electric imaging logging data. We automatically identify and extract fracture–vug information from the electric imaging images by adopting a path morphological operator that remains flexible enough to fit rectilinear and slightly curved structures because they are independent of the structuring element shape. The Otsu method was used to extract fracture–vug information from the background noise caused by the matrix. To accommodate the differences in scale and form of the different target regions,including fracture and vug path, operators with different lengths were selected for their recognition and extraction at the corresponding scale. Polynomial and elliptic functions are used to fit the extracted fractures and vugs, respectively, and the fracture–vug parameters are deduced from the fitted edge. Finally, test examples of numerical simulation data and several measured well data have been provided for the verification of the effectiveness and adaptability of the path morphology method in the application of electric imaging logging data processing. This also provides algorithm support for the fine evaluation of fracture–vug reservoirs.

关键词： Path morphology Image automatic identification Electric imaging logging Fracture–vug reservoir

Analysis of the ambiguity of log-constrained seismic impedance inversion

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Petroleum Science 2011年第2期8卷 151-156页

作者： Li Guofa Li Hao Ma Yanyan Xiong Jinliang State key laboratory of Petroleum Resources and prospecting China University of Petroleum (Beijing) Beijing 102249 China key laboratory of geophysical prospecting China National Petroleum Corporation Beijing 102249 China Dagang Oil field PetroChina Tianjin 300280 China

Although the ambiguity of seismic inversion is widely recognized in both theory and practice, so far as a concrete inversion example is concerned, there is not any objective, controllable method or any standard for how to evaluate and determine its ambiguity and reliability, especially for the high frequency components beyond the effective seismic frequency band. Taking log-constrained impedance inversion as an example, a new appraisal method is proposed on the basis of analyzing a simple geological model. Firstly, the inverted impedance model is transformed to a reflection coefficient series. Secondly, the maximum effective frequency of the real seismic data is chosen as a cutoff point and the reflection coefficient series is decomposed into two components by low-pass and high-pass filters. Thirdly, the geometrical reflection characteristics of the high-frequency components and that of the real seismic data are compared and analyzed. Then, the reliability of the inverted impedance model is appraised according to the similarity of geometrical characteristics between the high-frequency components and the real seismic data. The new method avoids some subjectivity in appraising the inverted result, and helps to enhance the reliability of reservoir prediction by impedance inversion technology.

关键词： Log-constrained impedance reflection coefficients seismic inversion ambiguity

Potential risks of spectrum whitening deconvolution——compared with well-driven deconvolution

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Petroleum Science 2009年第2期6卷 146-152页

作者： Li Guofa Zhou Hui Zhao Chao State key laboratory of Petroleum Resource and prospecting China University of Petroleum Beijing 102249 China key laboratory of CNPC geophysical Exploration China University of Petroleum Beijing 102249 China

Deconvolution is widely used to increase the resolution of seismic data. To compare the resolution ability of conventional spectrum whitening deconvolution to thin layers with that of welldriven deconvolution, a complex sedimentary geological model was designed, and then the simulated seismic data were processed respectively by each of the two methods. The amplitude spectrum of seismic data was almost white after spectrum whitening, but the wavelet resolution was low. The amplitude spectrum after well-driven deconvolution deviated from white spectrum, but the wavelet resolution was high. Further analysis showed that if an actual reflectivity series could not well satisfy the hypothesis of white spectrum, spectrum whitening deconvolution had a potential risk of wavelet distortion, which might lead to a pitfall in high resolution seismic data interpretation. On the other hand, the wavelet after well- driven deconvolution had higher resolution both in the time and frequency domains. It is favorable for high resolution seismic interpretation and reservoir prediction.

关键词： Well-driven high resolution spectrum whitening deconvolution seismic wavelet

Fluid substitution in a shaley sandstone reservoir at seismic scale

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Petroleum Science 2012年第1期9卷 31-37页

作者： Li Jingye State key laboratory of Petroleum Resource and prospecting China University of PetroleumBeijing 102249China CNPC key laboratory of geophysical Exploration China University of PetroleumBeijing 102249China

Shaley sandstone is heterogeneous at a seismic scale. Gassmann＇s equation is suited for fluid substitution in a homogeneous medium. To study the difference between shaley sandstone effective elastic moduli calculated by mean porosity as a homogeneous medium, and those calculated directly from the sub-volumes of the volume as a heterogeneous medium, computational experiments are conducted on Han＇s shaley sand model, the soft-sand model, the stiff-sand model, and their combination under the assumption that the shaley sandstone volume is made up of separate homogenous sub-volumes with independent porosity and clay content. Fluid substitutions are conducted by Gassmann＇s equation on rock volume and sub-volumes respectively. The computational data show that at seismic scale, there are minor differences between fluid substitution on rock volume and that on sub-volumes using Gassmann＇s equation. But fluid substitution on sub-volumes can take consideration of the effects of low porosity and low permeability sub-volumes, which can get more reasonable data, especially for low porosity reservoirs.

关键词： Fluid substitution Gassmann's equation shaley sandstone seismic scale

Wide/narrow azimuth acquisition footprints and their effects on seismic imaging

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Petroleum Science 2008年第4期5卷 308-313页

作者： Di Bangrang Xu Xiucang Wei Jianxin key laboratory of CNPC geophysical Exploration China University of Petroleum Beijing 102249 China State key laboratory of Petroleum Resource and prospecting China University of Petroleum Beijing 102249 China key laboratory of Earth prospecting and Information Technology China University of Petroleum Beijing 102249 China

Acquisition footprint is a new concept to describe the seismic noise in three-dimensional seismic exploration and it is closely related to geometry and observation shuttering. At present, the study on acquisition footprints has become a hot spot. In partnership with the Dagang Oilfield, we used the channel sand body seismic physical model to study the characteristics of wide/narrow azimuth acquisition footprints and analyzed and compared the two types of footprints and their effects on target imaging. In addition, the footprints caused by data processing of the normal moveout offset （NMO） stretching aberration were discussed. These footprints are located only in the shallow or middle layer in the time slice, and possibly affect the imaging of shallow target layers, and have no influence on deep target imaging. Seismic physical modeling has its advantages in the study of acquisition footprints.

关键词： Wide/narrow azimuth geometry acquisition footprint stretching aberration time slice seismic imaging