Zhanshan Xiao, Haining Zhang, Yi Wang, Hao Ni, Xuefeng Liu, Jianbin Zhao, Yonghao Zhang, Chenjun Zhang, Bo Wei
Unconventional reservoirs typically exhibit strong heterogeneity leading to a significant scale effect in digital rock physics simulations. To ensure the reliability of the simulation results, improving computational efficiency and increasing sample sizes are crucial. In this study, we present a numerical finite element simulation method for the acoustic and electrical properties of digital rock cores based on tetrahedral unstructured meshes. We calculated the elastic moduli and electrical resistivity of the Fontainebleau sandstone digital rock samples. A comparison was made between the tetrahedral mesh and the traditional voxel-based hexahedral mesh in terms of the accuracy and efficiency of finite element numerical simulations. The results indicate that this numerical simulation method based on the tetrahedral mesh exhibits high accuracy comparable to experimental results, and its computational efficiency is significantly improved compared to the traditional hexahedral mesh method. These findings highlight the advantages of this finite element simulation method in improving the computational scale and efficiency of digital rock simulations. It effectively addresses common computational resource constraints in dealing with large-scale core systems and facilitates better integration with engineering construction, well-logging instrument simulations, and production applications.
{"title":"Numerical simulations of the acoustic and electrical properties of digital rocks based on tetrahedral unstructured mesh","authors":"Zhanshan Xiao, Haining Zhang, Yi Wang, Hao Ni, Xuefeng Liu, Jianbin Zhao, Yonghao Zhang, Chenjun Zhang, Bo Wei","doi":"10.1093/jge/gxae077","DOIUrl":"https://doi.org/10.1093/jge/gxae077","url":null,"abstract":"\u0000 Unconventional reservoirs typically exhibit strong heterogeneity leading to a significant scale effect in digital rock physics simulations. To ensure the reliability of the simulation results, improving computational efficiency and increasing sample sizes are crucial. In this study, we present a numerical finite element simulation method for the acoustic and electrical properties of digital rock cores based on tetrahedral unstructured meshes. We calculated the elastic moduli and electrical resistivity of the Fontainebleau sandstone digital rock samples. A comparison was made between the tetrahedral mesh and the traditional voxel-based hexahedral mesh in terms of the accuracy and efficiency of finite element numerical simulations. The results indicate that this numerical simulation method based on the tetrahedral mesh exhibits high accuracy comparable to experimental results, and its computational efficiency is significantly improved compared to the traditional hexahedral mesh method. These findings highlight the advantages of this finite element simulation method in improving the computational scale and efficiency of digital rock simulations. It effectively addresses common computational resource constraints in dealing with large-scale core systems and facilitates better integration with engineering construction, well-logging instrument simulations, and production applications.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141800324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Honggang Mi, Yunan Liang, Qiang Sun, Chao Wei, Hongwei Song, Quanying Zhang, Ningchao Li, Xin Nie
The spiral borehole, primarily attributed to uneven force on the drill bit, poses a unique drilling and well logging challenge. In certain logging applications, this phenomenon can disrupt logging responses, introducing periodic fluctuations in the logging curve and complicating the interpretation process. To elucidate the impact of the spiral-borehole phenomenon on conventional radioactive logging methods, we conducted a simulation study examining its effects on traditional density tool (GGD), thermal-neutron porosity tool (TNP), and natural gamma tool (GR). Our findings reveal significant influences on density and porosity tool responses, with the amplitude of periodic fluctuations in logging curves closely linked to the groove depth of the spiral borehole. Conversely, the natural gamma tool exhibits minimal impact, with noticeable spiral-borehole effects causing limited fluctuations. Additionally, when the groove depth of the spiral borehole is fixed, the smaller the distance between the logging tool and the well wall, the closer the value obtained by the logging tool is to the true value of the formation parameter, and vice versa. This research offers theoretical insights for effectively correcting spiral-borehole effects in radioactive logging methods.
{"title":"Simulation study on the radioactive logging responses in the spiral borehole","authors":"Honggang Mi, Yunan Liang, Qiang Sun, Chao Wei, Hongwei Song, Quanying Zhang, Ningchao Li, Xin Nie","doi":"10.1093/jge/gxae078","DOIUrl":"https://doi.org/10.1093/jge/gxae078","url":null,"abstract":"\u0000 The spiral borehole, primarily attributed to uneven force on the drill bit, poses a unique drilling and well logging challenge. In certain logging applications, this phenomenon can disrupt logging responses, introducing periodic fluctuations in the logging curve and complicating the interpretation process. To elucidate the impact of the spiral-borehole phenomenon on conventional radioactive logging methods, we conducted a simulation study examining its effects on traditional density tool (GGD), thermal-neutron porosity tool (TNP), and natural gamma tool (GR). Our findings reveal significant influences on density and porosity tool responses, with the amplitude of periodic fluctuations in logging curves closely linked to the groove depth of the spiral borehole. Conversely, the natural gamma tool exhibits minimal impact, with noticeable spiral-borehole effects causing limited fluctuations. Additionally, when the groove depth of the spiral borehole is fixed, the smaller the distance between the logging tool and the well wall, the closer the value obtained by the logging tool is to the true value of the formation parameter, and vice versa. This research offers theoretical insights for effectively correcting spiral-borehole effects in radioactive logging methods.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141805904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crooked-line seismic survey has been widely used in oil and gas exploration in complex areas of western China. However, due to the unconventional acquisition geometry, current migration methods cannot fully account for the characteristics of crooked-line seismic data and may lead to poorly-resolved images with inaccurate kinematics. To mitigate this problem, we present in this paper a modified Kirchhoff prestack time migration well adapted to crooked-line seismic data. We first carry out a theoretical analysis on the propagation geometry of crooked-line seismic data and demonstrate problems associated with conventional 3D traveltime-based migration. Then, we present a modified 2D migration scheme based on the projection between the actual imaging trace within the vertical plane of seismic reflections and the output imaging trace. Compared with the 3D traveltime-based migration, our method not only ensures the accuracy of imaging depth but also improves the focusing and continuity of the migrated image. We use both synthetic and real data tests to validate the correctness and effectiveness of the proposed method.
{"title":"Kirchhoff Prestack time migration of crooked-line seismic data","authors":"Xiangzhong Chen, Yubo Yue, Xie Yu, Wei Li","doi":"10.1093/jge/gxae079","DOIUrl":"https://doi.org/10.1093/jge/gxae079","url":null,"abstract":"\u0000 Crooked-line seismic survey has been widely used in oil and gas exploration in complex areas of western China. However, due to the unconventional acquisition geometry, current migration methods cannot fully account for the characteristics of crooked-line seismic data and may lead to poorly-resolved images with inaccurate kinematics. To mitigate this problem, we present in this paper a modified Kirchhoff prestack time migration well adapted to crooked-line seismic data. We first carry out a theoretical analysis on the propagation geometry of crooked-line seismic data and demonstrate problems associated with conventional 3D traveltime-based migration. Then, we present a modified 2D migration scheme based on the projection between the actual imaging trace within the vertical plane of seismic reflections and the output imaging trace. Compared with the 3D traveltime-based migration, our method not only ensures the accuracy of imaging depth but also improves the focusing and continuity of the migrated image. We use both synthetic and real data tests to validate the correctness and effectiveness of the proposed method.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141814670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dan Yang, Yong Wang, Zhixian Gui, Zhili Chen, Jiaxin Huang
Reverse-time migration (RTM) is widely regarded as one of the most accurate migration methods available today. A crucial step in RTM involves extending seismic wavefields forward and backward. Compared to the conventional central finite difference (CFD) scheme, the combined compact difference (CCD) scheme offers several advantages, including a shorter difference operator and the suppression of numerical dispersion under coarse grids. These attributes conserve memory and enhance effectiveness while maintaining the same level of differential precision. In this article, we begin with the five-point eighth-order CCD scheme and utilize the least squares method and Lagrange multiplier method to optimize the difference coefficients. This optimization is guided by the concept of dispersion-relation-preserving (DRP). The result is the acquisition of an optimized combined compact difference (OCCD) scheme, further enhancing the ability to suppress numerical dispersion. We thoroughly compare and analyze dispersion relationships and stability conditions. In addition, we examine several crucial steps in the RTM of the second-order acoustic wave equation. These steps include absorption boundary conditions, boundary storage strategy, and Poynting vector imaging conditions. Finally, we apply both the CCD and OCCD schemes in the RTM of the layered model, graben model, and SEG/EAGE salt model. We compare these results with those obtained from CFD's RTM. Numerical findings demonstrate that, in contrast to the CFD scheme, the CCD scheme effectively suppresses numerical dispersion and enhances imaging accuracy. Moreover, the optimized OCCD scheme further improves the ability to suppress numerical dispersion and can obtain better imaging results, which is an effective reverse time migration method suitable for coarse grid conditions.
{"title":"2-D acoustic equation prestack reverse-time migration based on optimized combined compact difference scheme","authors":"Dan Yang, Yong Wang, Zhixian Gui, Zhili Chen, Jiaxin Huang","doi":"10.1093/jge/gxae073","DOIUrl":"https://doi.org/10.1093/jge/gxae073","url":null,"abstract":"\u0000 Reverse-time migration (RTM) is widely regarded as one of the most accurate migration methods available today. A crucial step in RTM involves extending seismic wavefields forward and backward. Compared to the conventional central finite difference (CFD) scheme, the combined compact difference (CCD) scheme offers several advantages, including a shorter difference operator and the suppression of numerical dispersion under coarse grids. These attributes conserve memory and enhance effectiveness while maintaining the same level of differential precision. In this article, we begin with the five-point eighth-order CCD scheme and utilize the least squares method and Lagrange multiplier method to optimize the difference coefficients. This optimization is guided by the concept of dispersion-relation-preserving (DRP). The result is the acquisition of an optimized combined compact difference (OCCD) scheme, further enhancing the ability to suppress numerical dispersion. We thoroughly compare and analyze dispersion relationships and stability conditions. In addition, we examine several crucial steps in the RTM of the second-order acoustic wave equation. These steps include absorption boundary conditions, boundary storage strategy, and Poynting vector imaging conditions. Finally, we apply both the CCD and OCCD schemes in the RTM of the layered model, graben model, and SEG/EAGE salt model. We compare these results with those obtained from CFD's RTM. Numerical findings demonstrate that, in contrast to the CFD scheme, the CCD scheme effectively suppresses numerical dispersion and enhances imaging accuracy. Moreover, the optimized OCCD scheme further improves the ability to suppress numerical dispersion and can obtain better imaging results, which is an effective reverse time migration method suitable for coarse grid conditions.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141815742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carbonate reservoirs are important targets for promoting the oil and gas reserve exploration and production in China. However, such reservoirs usually contain the developed complex pore structures, which heavily affect the precision in seismic prediction of petrophysical parameters. As one of the most important parameters to characterize reservoir rock, pore-related parameters can not only describe the pore structure, but also be used to evaluate the oil/gas bearing capabilities of potential reservoirs. The conventional rock-physics models (e.g. Gassmann's model) are formulated assuming fully-connected pores, which is unable to accurately capture the geometrical complexity in real rocks. In order to characterize the influences of multiple pores on the elastic properties, this work presents a rock-physics modelling method for carbonates, wherein the percentage composition of connected pores is equivalently quantified as the pore-connectivity factor. The method treats the pore-connectivity factor as an objective variable to characterize the spatial variations of pore structure. Specifically, the method combines the differential equivalent medium theory and Gassmann's model, and derives a linearized forward operator to quantitatively link porosity, water saturation, and pore-connectivity factor to seismic elastic parameters. According to the Bayesian linear inverse theory, the simultaneous estimation of petrophysical and pore-connectivity parameters is achieved. To characterize the statistical variations with multiple lithofacies, the Gaussian mixture model is employed to quantify the prior distribution of the objective variables. The posterior distribution of the objective variables is analytically expressed with the linearized forward operator. Numerical experiments show that the accuracy of the proposed method in predicting elastic parameters is improved. Compared with the conventional Xu-White model and the varying pore aspect ratio method, the accuracy of predicted P-wave velocity increases by 10.29% and 1.33%, respectively, and the predicted S-wave velocity increases by 6.44% and 0.03%, in terms of correlation coefficient. The application to the field data validates the effectiveness of the method, wherein the porosity and water saturation results help indicating the spatial distribution of potential reservoirs.
碳酸盐岩储层是促进中国油气储量勘探和生产的重要目标。然而，这类储层通常含有发育复杂的孔隙结构，严重影响了岩石物理参数的地震预测精度。作为描述储层岩石特征的重要参数之一，孔隙相关参数不仅可以描述孔隙结构，还可用于评价潜在储层的含油/气能力。传统的岩石物理模型（如 Gassmann 模型）是在假设孔隙完全连通的情况下建立的，无法准确反映实际岩石的几何复杂性。为了描述多孔隙对弹性特性的影响，本研究提出了一种碳酸盐岩的岩石物理建模方法，其中连通孔隙的百分比组成被等同量化为孔隙连通系数。该方法将孔隙连通系数作为一个客观变量来描述孔隙结构的空间变化。具体来说，该方法结合了微分等效介质理论和 Gassmann 模型，推导出一个线性化的前向算子，将孔隙度、含水饱和度和孔隙连通系数与地震弹性参数定量联系起来。根据贝叶斯线性反演理论，实现了岩石物理参数和孔隙连通性参数的同步估算。为了描述多种岩性的统计变化特征，采用了高斯混合模型来量化目标变量的先验分布。目标变量的后验分布用线性化前向算子分析表示。数值实验表明，所提出的方法提高了预测弹性参数的精度。与传统的 Xu-White 模型和不同孔隙纵横比方法相比，预测 P 波速度的精度分别提高了 10.29% 和 1.33%，预测 S 波速度的精度提高了 6.44% 和 0.03%（相关系数）。对现场数据的应用验证了该方法的有效性，其中孔隙度和含水饱和度结果有助于显示潜在储层的空间分布。
{"title":"Bayesian linearized inversion for petrophysical and pore-connectivity parameters with seismic elastic data of carbonate reservoirs","authors":"Jing Ba, Jiawei Chen, Qiang Guo, Wei Cheng, Zhifang Yang, Xiao Chen, Cong Luo","doi":"10.1093/jge/gxae076","DOIUrl":"https://doi.org/10.1093/jge/gxae076","url":null,"abstract":"\u0000 Carbonate reservoirs are important targets for promoting the oil and gas reserve exploration and production in China. However, such reservoirs usually contain the developed complex pore structures, which heavily affect the precision in seismic prediction of petrophysical parameters. As one of the most important parameters to characterize reservoir rock, pore-related parameters can not only describe the pore structure, but also be used to evaluate the oil/gas bearing capabilities of potential reservoirs. The conventional rock-physics models (e.g. Gassmann's model) are formulated assuming fully-connected pores, which is unable to accurately capture the geometrical complexity in real rocks. In order to characterize the influences of multiple pores on the elastic properties, this work presents a rock-physics modelling method for carbonates, wherein the percentage composition of connected pores is equivalently quantified as the pore-connectivity factor. The method treats the pore-connectivity factor as an objective variable to characterize the spatial variations of pore structure. Specifically, the method combines the differential equivalent medium theory and Gassmann's model, and derives a linearized forward operator to quantitatively link porosity, water saturation, and pore-connectivity factor to seismic elastic parameters. According to the Bayesian linear inverse theory, the simultaneous estimation of petrophysical and pore-connectivity parameters is achieved. To characterize the statistical variations with multiple lithofacies, the Gaussian mixture model is employed to quantify the prior distribution of the objective variables. The posterior distribution of the objective variables is analytically expressed with the linearized forward operator. Numerical experiments show that the accuracy of the proposed method in predicting elastic parameters is improved. Compared with the conventional Xu-White model and the varying pore aspect ratio method, the accuracy of predicted P-wave velocity increases by 10.29% and 1.33%, respectively, and the predicted S-wave velocity increases by 6.44% and 0.03%, in terms of correlation coefficient. The application to the field data validates the effectiveness of the method, wherein the porosity and water saturation results help indicating the spatial distribution of potential reservoirs.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141822636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qing-zhuang Mao, Yu Zhong, Yangting Liu, Mei He, Kun Zou, Hanming Gu, Kai Xu, Haibo Huang, Yuan Zhou, Zeyun Shi
Wave equation forward modeling is a useful method to study the propagation regulation of seismic wavefields. Finite difference (FD) is one of the most extensively employed numerical approaches for computing wavefields in earthquake and exploration seismology. However, the FD approach relying on regular grids often struggles with calculating wavefields in regions featuring surface topographies. The elastic wave equation can more accurately describe the propagation of seismic wavefields in elastic media compared to the acoustic wave equation. We introduce a new FD scheme to calculate the elastic wavefields in an isotropic model with a surface topography. The novel approach can use a conventional staggered grid FD(SGFD) approach based on regular grids. A new elastic model with a horizontal surface is first obtained from the nearby surface's elastic properties and the undulating terrain elevation. We subsequently employ a topography-related strategy to eliminate the effects of surface topographies on the seismic wavefields in models with irregular surface topographies. The merits of our proposed scheme lie in its ability to stable numerically compute wavefields in models with irregular surface topographies without altering the conventional SGFD relying on regular grids. To validate the effectiveness and practicality of our method, we utilize elastic models featuring complex surface topographies. Numerical experiments demonstrate that our approach efficiently calculates elastic wavefields in isotropic media with irregular topographies based on conventional SGFD.
{"title":"Simulate the elastic wavefields in media with an irregular surface topography based on staggered grid finite difference","authors":"Qing-zhuang Mao, Yu Zhong, Yangting Liu, Mei He, Kun Zou, Hanming Gu, Kai Xu, Haibo Huang, Yuan Zhou, Zeyun Shi","doi":"10.1093/jge/gxae075","DOIUrl":"https://doi.org/10.1093/jge/gxae075","url":null,"abstract":"\u0000 Wave equation forward modeling is a useful method to study the propagation regulation of seismic wavefields. Finite difference (FD) is one of the most extensively employed numerical approaches for computing wavefields in earthquake and exploration seismology. However, the FD approach relying on regular grids often struggles with calculating wavefields in regions featuring surface topographies. The elastic wave equation can more accurately describe the propagation of seismic wavefields in elastic media compared to the acoustic wave equation. We introduce a new FD scheme to calculate the elastic wavefields in an isotropic model with a surface topography. The novel approach can use a conventional staggered grid FD(SGFD) approach based on regular grids. A new elastic model with a horizontal surface is first obtained from the nearby surface's elastic properties and the undulating terrain elevation. We subsequently employ a topography-related strategy to eliminate the effects of surface topographies on the seismic wavefields in models with irregular surface topographies. The merits of our proposed scheme lie in its ability to stable numerically compute wavefields in models with irregular surface topographies without altering the conventional SGFD relying on regular grids. To validate the effectiveness and practicality of our method, we utilize elastic models featuring complex surface topographies. Numerical experiments demonstrate that our approach efficiently calculates elastic wavefields in isotropic media with irregular topographies based on conventional SGFD.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141828902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiang Li, Ziduo Hu, Zhen Zou, Fenglin Niu, Yancan Tian, Wei Liu, Gang Yao
Irregular topography of the free surface significantly affects seismic wavefield modelling, especially when employing finite-difference methods on rectangular grids. These methods represent the free surface as discrete points, resulting in a boundary that resembles a “staircase”. This approximation inaccurately represents surface topography, introducing errors in surface reflection traveltimes and generating artificial diffractions in wavefield simulation. We introduce a stable three-dimensional immersed boundary method (3DIBM) employing Cartesian coordinates to address these challenges. The 3DIBM enables the simulation of acoustic waves in media with complex topography through standard finite difference, extending the two-dimensional immersed boundary approach to compute spatial coordinates for ghost and mirror points in a three-dimensional space. Wavefield values at these points are obtained by three-dimensional spatial iterative symmetric interpolation, specifically through the Kaiser windowed sinc method. By implicitly implementing the free surface boundary condition in three dimensions, this method effectively reduces artificial diffractions and enhances the accuracy of reflection traveltime. The effectiveness and accuracy of 3DIBM are validated through numerical tests and pre-stack depth migration (PSDM) imaging with simulated data, demonstrating its superiority as a modelling engine for migration imaging and waveform inversion in three-dimensional land seismic analysis.
自由表面的不规则地形会严重影响地震波场建模，尤其是在矩形网格上采用有限差分方法时。这些方法将自由表面表示为离散点，导致边界类似于 "楼梯"。这种近似方法对地表地形的表示不准确，会带来地表反射旅行时间的误差，并在波场模拟中产生人为衍射。我们采用笛卡尔坐标引入了一种稳定的三维沉浸边界法（3DIBM）来应对这些挑战。三维沉浸边界法通过标准有限差分法模拟具有复杂地形的介质中的声波，扩展了二维沉浸边界法，计算三维空间中幽灵点和镜像点的空间坐标。这些点的波场值通过三维空间迭代对称插值法（特别是通过 Kaiser 窗口 sinc 法）获得。通过在三维空间隐式执行自由表面边界条件，该方法有效地减少了人为衍射，提高了反射旅行时间的精度。通过数值测试和叠前深度迁移（PSDM）成像模拟数据，验证了 3DIBM 的有效性和准确性，证明了其作为三维陆地地震分析中迁移成像和波形反演建模引擎的优越性。
{"title":"A Three-dimensional Immersed Boundary Method for Accurate Simulation of Acoustic Wavefields with Complex Surface Topography","authors":"Xiang Li, Ziduo Hu, Zhen Zou, Fenglin Niu, Yancan Tian, Wei Liu, Gang Yao","doi":"10.1093/jge/gxae074","DOIUrl":"https://doi.org/10.1093/jge/gxae074","url":null,"abstract":"\u0000 Irregular topography of the free surface significantly affects seismic wavefield modelling, especially when employing finite-difference methods on rectangular grids. These methods represent the free surface as discrete points, resulting in a boundary that resembles a “staircase”. This approximation inaccurately represents surface topography, introducing errors in surface reflection traveltimes and generating artificial diffractions in wavefield simulation. We introduce a stable three-dimensional immersed boundary method (3DIBM) employing Cartesian coordinates to address these challenges. The 3DIBM enables the simulation of acoustic waves in media with complex topography through standard finite difference, extending the two-dimensional immersed boundary approach to compute spatial coordinates for ghost and mirror points in a three-dimensional space. Wavefield values at these points are obtained by three-dimensional spatial iterative symmetric interpolation, specifically through the Kaiser windowed sinc method. By implicitly implementing the free surface boundary condition in three dimensions, this method effectively reduces artificial diffractions and enhances the accuracy of reflection traveltime. The effectiveness and accuracy of 3DIBM are validated through numerical tests and pre-stack depth migration (PSDM) imaging with simulated data, demonstrating its superiority as a modelling engine for migration imaging and waveform inversion in three-dimensional land seismic analysis.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141828834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The seismic data acquisition design with ‘two-wide and one-high’ geometry effectively improves the imaging quality of seismic records. However, when data is acquired in the real field, complex near surface conditions and environmental factors can introduce a variety of noises and gaps in seismic data, impacting the accuracy of seismic imaging. Currently, the method of low-rank matrix/tensor completion is commonly employed for data reconstruction after normal moveout (NMO). In complex subsurface medium, CMP (Common Midpoint) data processed with NMO may not satisfy the linear or quasi-linear assumptions within local data windows. Therefore, this paper exploits the inherent low-rank structure of high-dimensional data to propose a high-dimensional tensor completion method under the Frobenius-nuclear mixed norm constraint (FN-TC). This method unfolds the 4D data tensor into the frequency-space domain along its modes-(m, n) and subsequently imposes a non-convex Frobenius-nuclear mixed norm constraint on the unfolded approximate matrices. This approach closely approximates the rank function of the factor matrices, thereby enhancing the accuracy of data modeling. Theoretical and practical studies demonstrate that the novel FN-TC approach can effectively reconstruct high-dimensional seismic data and suppress noise, thereby providing data support for subsequent high-precision seismic imaging.
{"title":"Reconstruction and denoising of high-dimensional seismic data via Frobenius-nuclear mixed norm constraints","authors":"Fei Luo, Lanlan Yan, Jiexiong Cai, Kai Guo","doi":"10.1093/jge/gxae072","DOIUrl":"https://doi.org/10.1093/jge/gxae072","url":null,"abstract":"\u0000 The seismic data acquisition design with ‘two-wide and one-high’ geometry effectively improves the imaging quality of seismic records. However, when data is acquired in the real field, complex near surface conditions and environmental factors can introduce a variety of noises and gaps in seismic data, impacting the accuracy of seismic imaging. Currently, the method of low-rank matrix/tensor completion is commonly employed for data reconstruction after normal moveout (NMO). In complex subsurface medium, CMP (Common Midpoint) data processed with NMO may not satisfy the linear or quasi-linear assumptions within local data windows. Therefore, this paper exploits the inherent low-rank structure of high-dimensional data to propose a high-dimensional tensor completion method under the Frobenius-nuclear mixed norm constraint (FN-TC). This method unfolds the 4D data tensor into the frequency-space domain along its modes-(m, n) and subsequently imposes a non-convex Frobenius-nuclear mixed norm constraint on the unfolded approximate matrices. This approach closely approximates the rank function of the factor matrices, thereby enhancing the accuracy of data modeling. Theoretical and practical studies demonstrate that the novel FN-TC approach can effectively reconstruct high-dimensional seismic data and suppress noise, thereby providing data support for subsequent high-precision seismic imaging.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141651819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaodong Luan, Junjie Xue, Bin Chen, Xin Wu, Xiaoyin Ma
The inversion of artificial source electromagnetic method (EM) data fundamentally involves constructing a mathematical relationship between observable data and geological structures. The aim of imaging and inversion is to construct a geophysical model that matches the observable results, thereby realizing the identification of subsurface targets. The results of EM data inversion, due to the simplicity of geophysical models, limited inversion computing efficiency. Moreover, complexity of actual geological structures, and lack of onsite observable data, are often hindered by non-uniqueness. The challenge in the interpretation of artificial source EM data is in enhancing both the precision and expeditiousness of the inversion process. It can be classified into three main types for the EM data inversion: direct imaging inversion, deterministic inversion, and stochastic inversion. To enhance computational efficiency and reduce non-uniqueness in the results, effective inversion methods, prior geological information, geophysical data and comprehensive analysis can help mitigate the issue of non-uniqueness in EM data inversion, thereby leading to more rational geophysical interpretation results. With the progress of technology such as computing center and the development of artificial intelligence methods, future inversion techniques will become faster, more efficient and more intelligent, and will be applied to the interpretation of artificial source EM data.
{"title":"Analysis on stable imaging and inverse algorithm for artificial source EM data","authors":"Xiaodong Luan, Junjie Xue, Bin Chen, Xin Wu, Xiaoyin Ma","doi":"10.1093/jge/gxae071","DOIUrl":"https://doi.org/10.1093/jge/gxae071","url":null,"abstract":"\u0000 The inversion of artificial source electromagnetic method (EM) data fundamentally involves constructing a mathematical relationship between observable data and geological structures. The aim of imaging and inversion is to construct a geophysical model that matches the observable results, thereby realizing the identification of subsurface targets. The results of EM data inversion, due to the simplicity of geophysical models, limited inversion computing efficiency. Moreover, complexity of actual geological structures, and lack of onsite observable data, are often hindered by non-uniqueness. The challenge in the interpretation of artificial source EM data is in enhancing both the precision and expeditiousness of the inversion process. It can be classified into three main types for the EM data inversion: direct imaging inversion, deterministic inversion, and stochastic inversion. To enhance computational efficiency and reduce non-uniqueness in the results, effective inversion methods, prior geological information, geophysical data and comprehensive analysis can help mitigate the issue of non-uniqueness in EM data inversion, thereby leading to more rational geophysical interpretation results. With the progress of technology such as computing center and the development of artificial intelligence methods, future inversion techniques will become faster, more efficient and more intelligent, and will be applied to the interpretation of artificial source EM data.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141682588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kang Chen, Guangzhi Zhang, Guidong Di, Xin Guo, Long Wen, Qi Ran, Hualing Ma, Juncheng Dai
A comprehensive drilling of wells has been conducted in the Permian Qixia Formation in the central Sichuan Basin, revealing a significant number of dolomite reservoirs. High- and medium-porosity dolomite reservoirs are the main gas-producing reservoirs in the Qixia Formation. Seismic PP-wave data show a ‘bright spot’ for high-porosity dolomite reservoir formations but weak responses for medium-porosity dolomite reservoir formations, which is attributed to the inability of P waves to distinguish between medium-porosity reservoirs and limestone. However, medium-porosity dolomite and limestone have different S-wave velocities. Therefore, in this study, the identification of different-porosity dolomite reservoirs using multi-component seismic data was investigated. A comprehensive analysis of the elastic waves by forward modeling shows that the PS-wave amplitude is more sensitive to medium-porosity dolomite than the PP-wave amplitude. Therefore, medium-porosity dolomite reservoirs can be predicted using the amplitude attributes of the PS wave, and high-porosity dolomite reservoirs can be characterized using the PP wave. Meanwhile, the elastic parameter λρ (the product of Lame constant λ and density ρ), which is highly correlated with the dolomite content, can be used as an indicator of dolomite formations. Furthermore, compared to the results of PP-wave inversion, the elastic parameters derived from the joint inversion of PP- and PS-waves exhibited a better correspondence with the well-logging results. The comprehensive use of the seismic amplitude responses of PP and PS waves and multi-component seismic joint inversion can effectively predict high- and medium-porosity dolomite reservoirs. The predicted results can support the exploration and development of the Qixia Formation.
对四川盆地中部二叠系栖霞地层进行了全面钻探，发现了大量白云岩储层。高、中孔隙度白云岩储层是栖霞地层的主要产气储层。地震 PP 波数据显示，高孔隙度白云岩储层有 "亮点"，但中孔隙度白云岩储层的响应较弱，这是因为 P 波无法区分中孔隙度储层和石灰岩。然而，中等孔隙度白云岩和石灰岩的 S 波速度不同。因此，本研究利用多分量地震数据对不同孔隙度的白云岩储层进行了识别。通过正演模型对弹性波的综合分析表明，PS 波振幅对中孔隙度白云岩比 PP 波振幅更敏感。因此，可以利用 PS 波的振幅属性预测中孔隙度白云岩储层，利用 PP 波描述高孔隙度白云岩储层。同时，与白云岩含量高度相关的弹性参数λρ（拉美常数λ与密度ρ的乘积）可作为白云岩地层的指标。此外，与 PP 波反演结果相比，PP 波和 PS 波联合反演得出的弹性参数与测井结果的对应关系更好。综合利用PP波和PS波的地震振幅响应和多分量地震联合反演，可以有效预测高、中孔隙度白云岩储层。预测结果可为栖霞地层的勘探开发提供支持。
{"title":"Application of multi-component seismic data in identifying dolomite reservoirs in the Sichuan Basin","authors":"Kang Chen, Guangzhi Zhang, Guidong Di, Xin Guo, Long Wen, Qi Ran, Hualing Ma, Juncheng Dai","doi":"10.1093/jge/gxae068","DOIUrl":"https://doi.org/10.1093/jge/gxae068","url":null,"abstract":"\u0000 A comprehensive drilling of wells has been conducted in the Permian Qixia Formation in the central Sichuan Basin, revealing a significant number of dolomite reservoirs. High- and medium-porosity dolomite reservoirs are the main gas-producing reservoirs in the Qixia Formation. Seismic PP-wave data show a ‘bright spot’ for high-porosity dolomite reservoir formations but weak responses for medium-porosity dolomite reservoir formations, which is attributed to the inability of P waves to distinguish between medium-porosity reservoirs and limestone. However, medium-porosity dolomite and limestone have different S-wave velocities. Therefore, in this study, the identification of different-porosity dolomite reservoirs using multi-component seismic data was investigated. A comprehensive analysis of the elastic waves by forward modeling shows that the PS-wave amplitude is more sensitive to medium-porosity dolomite than the PP-wave amplitude. Therefore, medium-porosity dolomite reservoirs can be predicted using the amplitude attributes of the PS wave, and high-porosity dolomite reservoirs can be characterized using the PP wave. Meanwhile, the elastic parameter λρ (the product of Lame constant λ and density ρ), which is highly correlated with the dolomite content, can be used as an indicator of dolomite formations. Furthermore, compared to the results of PP-wave inversion, the elastic parameters derived from the joint inversion of PP- and PS-waves exhibited a better correspondence with the well-logging results. The comprehensive use of the seismic amplitude responses of PP and PS waves and multi-component seismic joint inversion can effectively predict high- and medium-porosity dolomite reservoirs. The predicted results can support the exploration and development of the Qixia Formation.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141343661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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