High-resolution and accurate acquisition of underground sonic properties is essential for energy detection and earth exploration. An effective method is proposed to accurately calculate sonic slowness at the highest resolution (receiver spacing of 0.5 ft) with high signal-to-noise ratio (S/N) ratio. The method utilizes super-virtual interferometry to reconstruct a large number of waveforms for slowness extraction using redundant information from overlapping inter-receiver spacing. Synthetic calculations are used to verify the validity of the method, especially in the case of strong noise interference and the presence of damaged channels in the array receivers, to accurately calculate the formation sonic slowness. The theory is applied to process and interpret low data-quality field measurements acquired at Brothers Volcano from the International Ocean Discovery Program (IODP). The processing analysis shows that in the case of very weak formation signals, the residual tool waves from the wireline sonic logging can still interfere with the high-resolution processing, while this method can effectively suppress this interference and accurately obtain the formation sonic velocity.
{"title":"Highest-Resolution High-Signal-to-Noise Ratio Sonic Slowness and Application to Brothers Volcano, Kermadec Arc, New Zealand","authors":"Song Xu","doi":"10.1190/geo2023-0347.1","DOIUrl":"https://doi.org/10.1190/geo2023-0347.1","url":null,"abstract":"High-resolution and accurate acquisition of underground sonic properties is essential for energy detection and earth exploration. An effective method is proposed to accurately calculate sonic slowness at the highest resolution (receiver spacing of 0.5 ft) with high signal-to-noise ratio (S/N) ratio. The method utilizes super-virtual interferometry to reconstruct a large number of waveforms for slowness extraction using redundant information from overlapping inter-receiver spacing. Synthetic calculations are used to verify the validity of the method, especially in the case of strong noise interference and the presence of damaged channels in the array receivers, to accurately calculate the formation sonic slowness. The theory is applied to process and interpret low data-quality field measurements acquired at Brothers Volcano from the International Ocean Discovery Program (IODP). The processing analysis shows that in the case of very weak formation signals, the residual tool waves from the wireline sonic logging can still interfere with the high-resolution processing, while this method can effectively suppress this interference and accurately obtain the formation sonic velocity.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139593499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shear-wave velocity is commonly used to understand the characteristics of the subsurface, which can be retrieved by inverting the phase or group velocity in Rayleigh wave surveys. Now, many studies have shown the advantage of analyzing group velocity over phase velocity to obtain the S-wave velocity. However, previous methods often suffer from poor resolution in estimating group velocity. In order to improve the resolution of the group velocity and reduce uncertainty in extracting dispersion curves, we propose a new method for estimation of the Rayleigh wave group velocity spectrum based on the slant stack and adaptive generalized S-transform with energy reassignment. This method incorporates the adaptive generalized S-transform and the energy reassignment technique to enhance the time-frequency representation, and then calculates the group velocity at each frequency using the slant stack. By conducting experiments with synthetic seismic records, it is evident that the new method has high resolution and accurate multimode group velocity calculations. Furthermore, when applied to a field dataset and synthetic record with noise, the method shows better results and noise robustness. This confirms the superior performance of the method at generating high-resolution dispersion images of the group velocity compared to previous approaches. The method will become an efficient tool in Rayleigh wave exploration.
剪切波速度通常用于了解地下的特征，可以通过反演瑞利波勘测中的相位或群速度来获取。目前，许多研究表明，分析群速度比相位速度更有利于获得 S 波速度。然而，以往的方法在估算群速度时往往存在分辨率低的问题。为了提高群速度的分辨率，减少提取频散曲线时的不确定性，我们提出了一种基于斜叠加和能量重分配的自适应广义 S 变换的估算瑞利波群速度谱的新方法。该方法结合了自适应广义 S 变换和能量重新分配技术，以增强时频表示，然后利用斜叠加计算每个频率的群速度。通过对合成地震记录进行实验，可以明显看出新方法具有高分辨率和精确的多模群速度计算。此外，当应用于野外数据集和带有噪声的合成记录时，该方法显示出更好的结果和噪声鲁棒性。这证明，与以前的方法相比，该方法在生成高分辨率群速度频散图像方面性能优越。该方法将成为瑞利波探测的有效工具。
{"title":"A new method for estimation of Rayleigh wave group velocity spectrum","authors":"Jiazhe Li, Xianhai Song, Xueqiang Zhang, Shichuan Yuan, Limin Wang, Kai Zhang","doi":"10.1190/geo2023-0458.1","DOIUrl":"https://doi.org/10.1190/geo2023-0458.1","url":null,"abstract":"Shear-wave velocity is commonly used to understand the characteristics of the subsurface, which can be retrieved by inverting the phase or group velocity in Rayleigh wave surveys. Now, many studies have shown the advantage of analyzing group velocity over phase velocity to obtain the S-wave velocity. However, previous methods often suffer from poor resolution in estimating group velocity. In order to improve the resolution of the group velocity and reduce uncertainty in extracting dispersion curves, we propose a new method for estimation of the Rayleigh wave group velocity spectrum based on the slant stack and adaptive generalized S-transform with energy reassignment. This method incorporates the adaptive generalized S-transform and the energy reassignment technique to enhance the time-frequency representation, and then calculates the group velocity at each frequency using the slant stack. By conducting experiments with synthetic seismic records, it is evident that the new method has high resolution and accurate multimode group velocity calculations. Furthermore, when applied to a field dataset and synthetic record with noise, the method shows better results and noise robustness. This confirms the superior performance of the method at generating high-resolution dispersion images of the group velocity compared to previous approaches. The method will become an efficient tool in Rayleigh wave exploration.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139594962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-26DOI: 10.1190/geo2024-0120-errata.1
Chen Tang, G. McMechan
{"title":"To: “From classical reflectivity-to-velocity inversion to full-waveform inversion using phase-modified and deconvolved reverse time migration images,” Chen Tang and George A. McMechan, 2017, GEOPHYSICS, 82, no. 1, S31–S49, https://doi.org/10.1190/geo2016-0033.1.","authors":"Chen Tang, G. McMechan","doi":"10.1190/geo2024-0120-errata.1","DOIUrl":"https://doi.org/10.1190/geo2024-0120-errata.1","url":null,"abstract":"<jats:p> </jats:p>","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139593817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In marine seismic exploration, towed-streamer seismic data acquisition stands out as a prevalent and economical approach. This data records scalar pressure and captures P waves including those that are converted from sub-seabed S waves. Theoretically, towed-streamer seismic data can be used to reconstruct S-wave fields for elastic wave imaging via backward extrapolation. Our research applies an acoustic-elastic coupled equation that includes a pressure term to perform elastic reverse time migration, using the pressure seismic data as the boundary condition for backward extrapolation. The feasibility of employing towed-streamer seismic data for elastic wave imaging of complex subsurface structures is confirmed through synthetic and field data examples. The investigation demonstrates how the smoothness of velocity and density models impacts the quality of elastic reverse time migration using towed-streamer seismic data. We find that using smooth velocity and density models for elastic wave imaging can enhance imaging quality by utilizing transmitted S waves. Furthermore, certain nonphysical S waves generated during backward extrapolation can contribute to PS images, as evidenced by a synthetic data example. Overall, the results indicate that the towed-streamer seismic data for elastic wave imaging has potential in marine seismic exploration. Moving forward, it is crucial to focus on refining the quality of PS images and reducing artifacts caused by the backward extrapolated nonphysical waves.
在海洋地震勘探中，拖曳流地震数据采集是一种普遍而经济的方法。这种数据记录标量压力并捕捉 P 波，包括从海底下 S 波转换而来的 P 波。从理论上讲，拖曳流地震数据可通过反推法重建 S 波场，用于弹性波成像。我们的研究应用了包含压力项的声弹耦合方程，利用压力地震数据作为反推的边界条件，进行弹性反向时间迁移。通过合成和现场数据实例，证实了利用拖曳流地震数据对复杂地下结构进行弹性波成像的可行性。研究证明了速度和密度模型的平滑度如何影响使用拖曳流地震数据进行弹性反向时间迁移的质量。我们发现，使用平滑的速度和密度模型进行弹性波成像，可以利用透射 S 波提高成像质量。此外，在反向外推过程中产生的某些非物理 S 波也有助于 PS 成像，一个合成数据实例就证明了这一点。总之，研究结果表明，用于弹性波成像的拖曳流地震数据在海洋地震勘探中具有潜力。展望未来，关键是要提高 PS 成像的质量，减少后推非物理波造成的伪影。
{"title":"Can towed-streamer seismic data be used for elastic wave imaging? Synthetic and field data examples","authors":"Rui Gong, Jianhua Geng, P. Yu, Xueying Hu","doi":"10.1190/geo2022-0534.1","DOIUrl":"https://doi.org/10.1190/geo2022-0534.1","url":null,"abstract":"In marine seismic exploration, towed-streamer seismic data acquisition stands out as a prevalent and economical approach. This data records scalar pressure and captures P waves including those that are converted from sub-seabed S waves. Theoretically, towed-streamer seismic data can be used to reconstruct S-wave fields for elastic wave imaging via backward extrapolation. Our research applies an acoustic-elastic coupled equation that includes a pressure term to perform elastic reverse time migration, using the pressure seismic data as the boundary condition for backward extrapolation. The feasibility of employing towed-streamer seismic data for elastic wave imaging of complex subsurface structures is confirmed through synthetic and field data examples. The investigation demonstrates how the smoothness of velocity and density models impacts the quality of elastic reverse time migration using towed-streamer seismic data. We find that using smooth velocity and density models for elastic wave imaging can enhance imaging quality by utilizing transmitted S waves. Furthermore, certain nonphysical S waves generated during backward extrapolation can contribute to PS images, as evidenced by a synthetic data example. Overall, the results indicate that the towed-streamer seismic data for elastic wave imaging has potential in marine seismic exploration. Moving forward, it is crucial to focus on refining the quality of PS images and reducing artifacts caused by the backward extrapolated nonphysical waves.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139595697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Crepaldi, L. D. de Figueiredo, Andrea Zerilli, Ivan S. Oliveira, J. Sinnecker
A Bayesian approach is proposed to estimate litho-fluid facies and other rock properties conditioned on seismic and electromagnetic data for reservoir characterization. Prior distributions are assumed to be facies-related Gaussian modes of geophysical rock properties directly acquired or converted from petrophysical properties by calibrated rock physics modeling. An original generalization includes two distributions in the same marginalization integral, analytically solved under a linearized Gaussian assumption to provide a facies model likelihood conditioned on geophysical data. Since computing this probability for all possible facies configurations may be impractical, a Markov Chain Monte Carlo algorithm efficiently samples models to provide a full posterior distribution. The linearized Gaussian approach allows the computation of the conditional distributions of geophysical and petrophysical rock properties by applying local deterministic inversions over the many sampled facies models. The inversion uses simulated geophysical data from a 1D synthetic model based on the geological scenario and a well from a selected marine oil field. Two other wells from the same reservoir were used to gather prior distributions. Data from the well, calibration of the rock physics modeling, and facies matching between the priors and the synthetic model are presented and discussed. Numerical tests validate nonlinear forward modeling adaptations on the assumed linearized Gaussian approach. The simulated stand-alone and joint geophysical datasets are then inverted for litho-fluid facies models under different prior inputs. Two challenging geoelectric scenarios were also tested, one with lower resistivity contrasts and another with a misguided background model. All results demonstrate a gain in precision and accuracy when associating both geophysical signals to estimate the oil column. Facies-conditioned inversions for the rock properties also show potential for quantitative reservoir interpretations.
{"title":"Bayesian joint inversion of seismic and electromagnetic data for reservoir litho-fluid facies including geophysical and petrophysical rock properties","authors":"J. Crepaldi, L. D. de Figueiredo, Andrea Zerilli, Ivan S. Oliveira, J. Sinnecker","doi":"10.1190/geo2022-0546.1","DOIUrl":"https://doi.org/10.1190/geo2022-0546.1","url":null,"abstract":"A Bayesian approach is proposed to estimate litho-fluid facies and other rock properties conditioned on seismic and electromagnetic data for reservoir characterization. Prior distributions are assumed to be facies-related Gaussian modes of geophysical rock properties directly acquired or converted from petrophysical properties by calibrated rock physics modeling. An original generalization includes two distributions in the same marginalization integral, analytically solved under a linearized Gaussian assumption to provide a facies model likelihood conditioned on geophysical data. Since computing this probability for all possible facies configurations may be impractical, a Markov Chain Monte Carlo algorithm efficiently samples models to provide a full posterior distribution. The linearized Gaussian approach allows the computation of the conditional distributions of geophysical and petrophysical rock properties by applying local deterministic inversions over the many sampled facies models. The inversion uses simulated geophysical data from a 1D synthetic model based on the geological scenario and a well from a selected marine oil field. Two other wells from the same reservoir were used to gather prior distributions. Data from the well, calibration of the rock physics modeling, and facies matching between the priors and the synthetic model are presented and discussed. Numerical tests validate nonlinear forward modeling adaptations on the assumed linearized Gaussian approach. The simulated stand-alone and joint geophysical datasets are then inverted for litho-fluid facies models under different prior inputs. Two challenging geoelectric scenarios were also tested, one with lower resistivity contrasts and another with a misguided background model. All results demonstrate a gain in precision and accuracy when associating both geophysical signals to estimate the oil column. Facies-conditioned inversions for the rock properties also show potential for quantitative reservoir interpretations.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139596995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhiyong Wang, Guochang Liu, Chao Li, Lanting Shi, Zixu Wang
Random noise in seismic records affects the accuracy of effective signal identification, making it difficult for subsequent seismic data processing, imaging, and interpretation. Therefore, random noise attenuation has always been an important step in seismic data processing, especially for 3D data. In recent years, multi-component exploration has been developed rapidly. However, the common method for processing multi-component data is to process each component separately resulting in the correlation between multi-component data being neglected. For 3D multi-component data, we propose a multi-component adaptive prediction filter (MAPF) based on noncausal regularized nonstationary autoregressive models to implement random noise attenuation in the t- x- y domain. The MAPF for multi-component signals can be used to identify the potential correlations and differences between each pair of components, providing not only a robust analysis of individual components but also effective information about the consistency and differences between each component with more information and constraints compared to traditional single-component prediction. Moreover, it can obtain smooth non-stationary prediction coefficients by solving the least squares problem with shaping regularization. The example results demonstrate that the MAPF method is superior to the traditional adaptive prediction filtering (APF) method. Furthermore, since the multi-component method requires more coefficients and takes longer time to predict than the single-component method, we further propose a fast multi-component adaptive prediction filter (FMAPF) combining the data pooling and coefficient reconstruction strategies. The example results demonstrate that the FMAPF method is effective at denoising and greatly improves computational efficiency. The method comes with a slight decrease in computational accuracy.
地震记录中的随机噪声会影响有效信号识别的准确性，给后续的地震数据处理、成像和解释带来困难。因此，随机噪声衰减一直是地震数据处理，尤其是三维数据处理的重要步骤。近年来，多分量勘探得到了快速发展。然而，处理多分量数据的常用方法是单独处理每个分量，导致多分量数据之间的相关性被忽视。针对三维多分量数据，我们提出了一种基于非因果正则化非平稳自回归模型的多分量自适应预测滤波器（MAPF），以实现 t- x- y 域的随机噪声衰减。多分量信号的 MAPF 可用于识别每对分量之间的潜在相关性和差异，与传统的单分量预测相比，它不仅能对单个分量进行稳健分析，还能提供有关各分量之间一致性和差异的有效信息，并具有更多的信息和约束条件。此外，它还可以通过求解具有整形正则化的最小二乘问题，获得平滑的非平稳预测系数。实例结果表明，MAPF 方法优于传统的自适应预测滤波（APF）方法。此外，由于多分量方法比单分量方法需要更多的系数和更长的预测时间，我们进一步提出了一种结合数据池和系数重构策略的快速多分量自适应预测滤波器（FMAPF）。实例结果表明，FMAPF 方法在去噪方面非常有效，并大大提高了计算效率。该方法的计算精度略有下降。
{"title":"Random noise attenuation of 3D multi-component seismic data using fast adaptive prediction filter","authors":"Zhiyong Wang, Guochang Liu, Chao Li, Lanting Shi, Zixu Wang","doi":"10.1190/geo2023-0195.1","DOIUrl":"https://doi.org/10.1190/geo2023-0195.1","url":null,"abstract":"Random noise in seismic records affects the accuracy of effective signal identification, making it difficult for subsequent seismic data processing, imaging, and interpretation. Therefore, random noise attenuation has always been an important step in seismic data processing, especially for 3D data. In recent years, multi-component exploration has been developed rapidly. However, the common method for processing multi-component data is to process each component separately resulting in the correlation between multi-component data being neglected. For 3D multi-component data, we propose a multi-component adaptive prediction filter (MAPF) based on noncausal regularized nonstationary autoregressive models to implement random noise attenuation in the t- x- y domain. The MAPF for multi-component signals can be used to identify the potential correlations and differences between each pair of components, providing not only a robust analysis of individual components but also effective information about the consistency and differences between each component with more information and constraints compared to traditional single-component prediction. Moreover, it can obtain smooth non-stationary prediction coefficients by solving the least squares problem with shaping regularization. The example results demonstrate that the MAPF method is superior to the traditional adaptive prediction filtering (APF) method. Furthermore, since the multi-component method requires more coefficients and takes longer time to predict than the single-component method, we further propose a fast multi-component adaptive prediction filter (FMAPF) combining the data pooling and coefficient reconstruction strategies. The example results demonstrate that the FMAPF method is effective at denoising and greatly improves computational efficiency. The method comes with a slight decrease in computational accuracy.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139596483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-24DOI: 10.1190/geo2024-0118-geodis.1
Geophysics publishes abstracts of dissertations and titles of master’s theses in print and online. Recent graduates are invited to submit their abstracts or titles by completing and submitting the appropriate form found at http://seg.org/dissertationabstracts . Abstracts and titles will be reviewed and accepted or rejected based on their relevance to the readers of Geophysics. Abstracts must be written in English and defended in 2020 or later.
{"title":"Geophysics Dissertation Abstracts","authors":"","doi":"10.1190/geo2024-0118-geodis.1","DOIUrl":"https://doi.org/10.1190/geo2024-0118-geodis.1","url":null,"abstract":"Geophysics publishes abstracts of dissertations and titles of master’s theses in print and online. Recent graduates are invited to submit their abstracts or titles by completing and submitting the appropriate form found at http://seg.org/dissertationabstracts . Abstracts and titles will be reviewed and accepted or rejected based on their relevance to the readers of Geophysics. Abstracts must be written in English and defended in 2020 or later.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139600476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wenhao Wang, Shengqing Li, Junxin Guo, Long Zhao, Shangjing Guo, Yuanda Su, Xiao-Ming Tang
Owing to the complex structural characteristics of aligned fractured rocks with a fluid-saturated porous background, many existing single-wave attenuation mechanism models cannot accurately characterize measuring multiband SV wave data. Moreover, the coupled effect of wave-induced fluid flow between fractures and the background (FB-WIFF) and elastic scattering (ES) from the fractures leads to ambiguity in the elastic response of the SV wave. Using Biots theory and mixed boundary constraints, we derived exact solutions to the scattering problem for a single penny-shaped fracture with an oblique incident SV wave. Furthermore, we developed a theoretical model for a set of aligned fractures by using Foldy's scheme. The numerical results showed that the FB-WIFF, ES of fractures, and their coupling effects were mainly responsible for wave dispersion and attenuation. The FB-WIFF occurs primarily in the low-frequency seismic exploration frequency band, whereas the ES of the fracture surface depends on the relationship between the wavelength and fracture size. In addition, we validated the accuracy and effectiveness of our model by comparing it with an existing interpolation approximation model and previous experimental measurements. The analysis results of this work can explain the acoustic response of SV wave experimental data in different frequency bands and theoretically support fracture detection and characterization.
由于具有流体饱和多孔背景的排列断裂岩石的复杂结构特征，许多现有的单波衰减机制模型无法准确描述测量多波段 SV 波数据。此外，裂缝与背景之间的波致流体流动（FB-WIFF）和裂缝的弹性散射（ES）的耦合效应导致 SV 波的弹性响应模糊不清。利用 Biots 理论和混合边界约束，我们推导出了斜入射 SV 波作用下单笔形断裂散射问题的精确解。此外，我们还利用 Foldy 方案为一组排列整齐的断裂建立了理论模型。数值结果表明，FB-WIFF、断裂 ES 及其耦合效应是造成波的色散和衰减的主要原因。FB-WIFF 主要发生在低频地震勘探频段，而断裂面 ES 则取决于波长与断裂尺寸之间的关系。此外，我们通过与现有的内插近似模型和之前的实验测量结果进行比较，验证了我们的模型的准确性和有效性。这项工作的分析结果可以解释不同频段 SV 波实验数据的声学响应，并为断裂检测和表征提供理论支持。
{"title":"Dispersion and attenuation characteristics of obliquely incident SV wave in a fluid-saturated porous rock containing aligned penny-shaped fractures","authors":"Wenhao Wang, Shengqing Li, Junxin Guo, Long Zhao, Shangjing Guo, Yuanda Su, Xiao-Ming Tang","doi":"10.1190/geo2023-0170.1","DOIUrl":"https://doi.org/10.1190/geo2023-0170.1","url":null,"abstract":"Owing to the complex structural characteristics of aligned fractured rocks with a fluid-saturated porous background, many existing single-wave attenuation mechanism models cannot accurately characterize measuring multiband SV wave data. Moreover, the coupled effect of wave-induced fluid flow between fractures and the background (FB-WIFF) and elastic scattering (ES) from the fractures leads to ambiguity in the elastic response of the SV wave. Using Biots theory and mixed boundary constraints, we derived exact solutions to the scattering problem for a single penny-shaped fracture with an oblique incident SV wave. Furthermore, we developed a theoretical model for a set of aligned fractures by using Foldy's scheme. The numerical results showed that the FB-WIFF, ES of fractures, and their coupling effects were mainly responsible for wave dispersion and attenuation. The FB-WIFF occurs primarily in the low-frequency seismic exploration frequency band, whereas the ES of the fracture surface depends on the relationship between the wavelength and fracture size. In addition, we validated the accuracy and effectiveness of our model by comparing it with an existing interpolation approximation model and previous experimental measurements. The analysis results of this work can explain the acoustic response of SV wave experimental data in different frequency bands and theoretically support fracture detection and characterization.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139605084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohsen Kazemnia Kakhki, Ahmadreza Mokhtari, W. Mansur
Cohen class distributions are well-known time-frequency distributions that have been widely used to analyze different signals. However, they are impractical for signal filtering as they only provide amplitude spectra and suffer from cross-term. In this paper, deconvolutive STFT (DSTFT) is developed by estimating phase spectra and updating moduli to address residual cross-terms. We use DSTFT moduli as weights and apply a weighted least squares technique to estimate a high-resolution and almost cross-term-free Wigner-Ville distribution. Through numerical tests, we demonstrate that choosing the optimal window length can minimize cross-terms in STFT and DSTFT spectrograms, and employing thresholding or re-weighting techniques can eliminate weights associated with noise. The performance of the proposed method is demonstrated using synthetic and two real seismic wavefield separation problems, including ground roll removal in seismic shot records and polarization analysis in seismology. The results show the high performance of the proposed method in estimating phase spectra and filtering seismic data.
{"title":"Time-Frequency Phase Retrieval for Deconvolutive Short-Time Fourier Transform","authors":"Mohsen Kazemnia Kakhki, Ahmadreza Mokhtari, W. Mansur","doi":"10.1190/geo2023-0563.1","DOIUrl":"https://doi.org/10.1190/geo2023-0563.1","url":null,"abstract":"Cohen class distributions are well-known time-frequency distributions that have been widely used to analyze different signals. However, they are impractical for signal filtering as they only provide amplitude spectra and suffer from cross-term. In this paper, deconvolutive STFT (DSTFT) is developed by estimating phase spectra and updating moduli to address residual cross-terms. We use DSTFT moduli as weights and apply a weighted least squares technique to estimate a high-resolution and almost cross-term-free Wigner-Ville distribution. Through numerical tests, we demonstrate that choosing the optimal window length can minimize cross-terms in STFT and DSTFT spectrograms, and employing thresholding or re-weighting techniques can eliminate weights associated with noise. The performance of the proposed method is demonstrated using synthetic and two real seismic wavefield separation problems, including ground roll removal in seismic shot records and polarization analysis in seismology. The results show the high performance of the proposed method in estimating phase spectra and filtering seismic data.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139604216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Huan Cao, Yang Zhao, Chenggang Xian, Hengyu Tang, Lanlan Yan, Da Shuai, Lele Zhang, Yinghao Shen, Shichang Li
The anisotropic parameters inversion in horizontal transverse isotropy (HTI) medium plays an important role in predicting the fracture density as well as the anisotropic in-situ stress for unconventional reservoirs. The current industry practice is to use the azimuthal PP-wave reflection coefficient to estimate the HTI anisotropic parameters. Based on the linear slip theory, this study adapts azimuthal P-wave phase velocity to calculate the HTI anisotropic parameters and demonstrates superiority against the conventional azimuthal PP-wave reflection coefficient. Specifically, we first verify that the azimuthal P-wave phase velocity is more feasible for the HTI elliptical fitting rather than the azimuthal PP-wave reflection coefficient due to the analytical formulations. Second, we sort the prestack wide-azimuth (WAZ) data into offset vector tile (OVT) sectors and perform the AVO (Amplitude Versus Offset) inversion at each azimuth. Third, the elliptical fitting is applied to the obtained azimuthal P-wave phase velocities to estimate the HTI anisotropic parameters, fracture density, and fracture direction. Fourth, based on the HTI mechanical earth model (MEM), we formulate the 3D in-situ stress as a function of the obtained elastic parameters and fracture compliance, which exhibits a potential for computational efficiency. Finally, field examples from the Zhaotong area, China demonstrate that the estimated fracture density and anisotropic in-situ stress present high accuracy and resolution compared with conventional methods. The dominant stress regime in the study area is a strike-slip faulting regime with a governing orientation of NE-SW and presents good alignments with well logs, which demonstrates the reliability and accuracy of our proposed method for predicting fracture density and anisotropic in-situ stress.
水平横向各向同性（HTI）介质的各向异性参数反演在预测非常规储层的裂缝密度和各向异性原位应力方面发挥着重要作用。目前的行业做法是使用方位 PP 波反射系数来估算 HTI 各向异性参数。本研究以线性滑移理论为基础，采用方位 P 波相位速度计算 HTI 各向异性参数，并证明其优于传统的方位 PP 波反射系数。具体来说，我们首先验证了由于分析公式的原因，方位角 P 波相位速度比方位角 PP 波反射系数更适用于 HTI 椭圆拟合。其次，我们将预叠加宽方位（WAZ）数据分类为偏移矢量瓦（OVT）扇区，并在每个方位角进行AVO（振幅与偏移）反演。第三，对获得的方位 P 波相位速度进行椭圆拟合，以估算 HTI 各向异性参数、裂缝密度和裂缝方向。第四，基于 HTI 地球力学模型（MEM），我们将三维原位应力表述为所获得的弹性参数和断裂顺应性的函数，这显示了计算效率的潜力。最后，中国昭通地区的野外实例表明，与传统方法相比，估计的断裂密度和各向异性原位应力具有较高的精度和分辨率。研究区域的主要应力机制是走向为 NE-SW 的走向滑动断层机制，与测井记录吻合良好，这证明了我们提出的预测压裂密度和各向异性原位应力方法的可靠性和准确性。
{"title":"HTI ANISOTROPY PARAMETERS INVERSION VIA AZIMUTHAL SEISMIC VELOCITY ANISOTROPY AND ITS APPLICATION TO ANISOTROPIC 3D IN-SITU STRESS ESTIMATION","authors":"Huan Cao, Yang Zhao, Chenggang Xian, Hengyu Tang, Lanlan Yan, Da Shuai, Lele Zhang, Yinghao Shen, Shichang Li","doi":"10.1190/geo2023-0377.1","DOIUrl":"https://doi.org/10.1190/geo2023-0377.1","url":null,"abstract":"The anisotropic parameters inversion in horizontal transverse isotropy (HTI) medium plays an important role in predicting the fracture density as well as the anisotropic in-situ stress for unconventional reservoirs. The current industry practice is to use the azimuthal PP-wave reflection coefficient to estimate the HTI anisotropic parameters. Based on the linear slip theory, this study adapts azimuthal P-wave phase velocity to calculate the HTI anisotropic parameters and demonstrates superiority against the conventional azimuthal PP-wave reflection coefficient. Specifically, we first verify that the azimuthal P-wave phase velocity is more feasible for the HTI elliptical fitting rather than the azimuthal PP-wave reflection coefficient due to the analytical formulations. Second, we sort the prestack wide-azimuth (WAZ) data into offset vector tile (OVT) sectors and perform the AVO (Amplitude Versus Offset) inversion at each azimuth. Third, the elliptical fitting is applied to the obtained azimuthal P-wave phase velocities to estimate the HTI anisotropic parameters, fracture density, and fracture direction. Fourth, based on the HTI mechanical earth model (MEM), we formulate the 3D in-situ stress as a function of the obtained elastic parameters and fracture compliance, which exhibits a potential for computational efficiency. Finally, field examples from the Zhaotong area, China demonstrate that the estimated fracture density and anisotropic in-situ stress present high accuracy and resolution compared with conventional methods. The dominant stress regime in the study area is a strike-slip faulting regime with a governing orientation of NE-SW and presents good alignments with well logs, which demonstrates the reliability and accuracy of our proposed method for predicting fracture density and anisotropic in-situ stress.","PeriodicalId":509604,"journal":{"name":"GEOPHYSICS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139606773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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