Xingli Zhang, Yaping Zhang, ZuoGang Liu, Hongjuan Wang
Rank-reduction (RR) has become a hotspot in seismic data reconstruction research in recent years. Traditional RR methods generally use the nuclear norm as a convex proxy for rank, but these methods overly penalise large singular values, leading to reconstruction results that deviate from the optimal solution. In this paper, we propose a tensor robust principal component analysis (TRPCA) model with minimisation of the partial sum of tensor nuclear norm (PSTNN) for three-dimensional (3D) reconstruction of seismic data. PSTNN minimises only the partial singular values and can approximate the rank function more accurately. TRPCA can accurately recover the 3D tensor corrupted by sparse errors, improving the accuracy of seismic data reconstruction. The experimental results of the simulated data and real data show that the reconstruction effect of the proposed method on the 3D seismic data is better than the compared methods.
{"title":"Three-dimensional seismic data reconstruction via partial sum of tensor nuclear norm minimisation","authors":"Xingli Zhang, Yaping Zhang, ZuoGang Liu, Hongjuan Wang","doi":"10.1093/jge/gxad012","DOIUrl":"https://doi.org/10.1093/jge/gxad012","url":null,"abstract":"\u0000 Rank-reduction (RR) has become a hotspot in seismic data reconstruction research in recent years. Traditional RR methods generally use the nuclear norm as a convex proxy for rank, but these methods overly penalise large singular values, leading to reconstruction results that deviate from the optimal solution. In this paper, we propose a tensor robust principal component analysis (TRPCA) model with minimisation of the partial sum of tensor nuclear norm (PSTNN) for three-dimensional (3D) reconstruction of seismic data. PSTNN minimises only the partial singular values and can approximate the rank function more accurately. TRPCA can accurately recover the 3D tensor corrupted by sparse errors, improving the accuracy of seismic data reconstruction. The experimental results of the simulated data and real data show that the reconstruction effect of the proposed method on the 3D seismic data is better than the compared methods.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49447740","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}
Electrical resistivity and induced polarization (ER-IP) surveys were carried out in Eastern Labo, Bicol, Philippines, to assess the potential Cu-Au mineralization in pyroclastic-covered areas. An electrical resistivity tomography method with a dipole–dipole array was used, and the L1 norm (robust) inversion approach was employed to generate the 16 2D ER-IP models. The analysis of the resistivity and chargeability classified the underlying lithology into eight zones. Zones from C to F are the potential mineralized zones, while Zones A and B (Labo Volcanic Complex) and Zones G and H (Tumbaga Formation and Tamisan Diorite) are the non-mineralized zones. Zone C, represented by low chargeability (<15 mV V−1) and intermediate resistivity (15–100 Ω-m) values, is characterized by a high concentration of disseminated sulfide minerals (e.g. chalcopyrite). Zone D has a chargeability range comparable to Zone C but higher resistivity (>100 Ω-m), which might be due to silicification. Zone E corresponds to the oxide zone with concentrated sulfide minerals along clayey, weathered, fractured areas; it has moderate to high chargeability (>15 mV V−1) and low resistivity (<15 Ω-m) signatures. Zone F has a similar resistivity range to Zone E but has lower chargeability (<15 mV V−1) values. The interpreted underlying lithological units were confirmed using borehole data. Because of the extensive occurrence of high chargeability zones with moderate resistivity anomalies, potentially mineralized areas for further investigation (e.g. drilling) were identified in the north-eastern portion of the study area.
{"title":"Characterization of potential Cu-Au mineralization using electrical resistivity and induced polarization methods: a case study in Eastern Labo, Bicol, Philippines","authors":"M. A. A. Casulla, H. Mizunaga","doi":"10.1093/jge/gxad018","DOIUrl":"https://doi.org/10.1093/jge/gxad018","url":null,"abstract":"\u0000 Electrical resistivity and induced polarization (ER-IP) surveys were carried out in Eastern Labo, Bicol, Philippines, to assess the potential Cu-Au mineralization in pyroclastic-covered areas. An electrical resistivity tomography method with a dipole–dipole array was used, and the L1 norm (robust) inversion approach was employed to generate the 16 2D ER-IP models. The analysis of the resistivity and chargeability classified the underlying lithology into eight zones. Zones from C to F are the potential mineralized zones, while Zones A and B (Labo Volcanic Complex) and Zones G and H (Tumbaga Formation and Tamisan Diorite) are the non-mineralized zones. Zone C, represented by low chargeability (<15 mV V−1) and intermediate resistivity (15–100 Ω-m) values, is characterized by a high concentration of disseminated sulfide minerals (e.g. chalcopyrite). Zone D has a chargeability range comparable to Zone C but higher resistivity (>100 Ω-m), which might be due to silicification. Zone E corresponds to the oxide zone with concentrated sulfide minerals along clayey, weathered, fractured areas; it has moderate to high chargeability (>15 mV V−1) and low resistivity (<15 Ω-m) signatures. Zone F has a similar resistivity range to Zone E but has lower chargeability (<15 mV V−1) values. The interpreted underlying lithological units were confirmed using borehole data. Because of the extensive occurrence of high chargeability zones with moderate resistivity anomalies, potentially mineralized areas for further investigation (e.g. drilling) were identified in the north-eastern portion of the study area.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43628341","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}
Using multigeophysical exploration techniques is a common way for deep targets to be explored in complex survey areas. How to locate an unknown underground target using multiple datasets is a great challenge. The useful information in the multisource geophysical model can be extracted and fused with the help of data fusion, which also works well to correct the interpretation divergence brought on by expert experience, with image feature extraction being the key step in the fusion of the geophysical models. Traditionally, this method is often used for these kinds of geophysical images, but it significantly reduces the efficiency of feature extraction. As a result, we propose a novel method based on a transfer learning method to extract the features of multisource images. First, the ResNet50 network is used to extract the initial features of the images. Owing to the problems of feature redundancy and fuzzy features in initial features, Spearman and zero phase component analysis can be used to achieve feature reduction and enhancement, which can further improve the computational efficiency and fusion accuracy in fusion. Finally, the fusion image is obtained using fusion rules that we designed based on the current state. The algorithm's reliability is tested using field data from the Iliamna Volcano. The case study demonstrates the effectiveness of the proposed strategy, which also offers a novel way to locate subsurface targets.
{"title":"Application of the transfer learning method in multisource geophysical data fusion","authors":"Pengfei Lv, G. Xue, Weiying Chen, Wanting Song","doi":"10.1093/jge/gxad011","DOIUrl":"https://doi.org/10.1093/jge/gxad011","url":null,"abstract":"\u0000 Using multigeophysical exploration techniques is a common way for deep targets to be explored in complex survey areas. How to locate an unknown underground target using multiple datasets is a great challenge. The useful information in the multisource geophysical model can be extracted and fused with the help of data fusion, which also works well to correct the interpretation divergence brought on by expert experience, with image feature extraction being the key step in the fusion of the geophysical models. Traditionally, this method is often used for these kinds of geophysical images, but it significantly reduces the efficiency of feature extraction. As a result, we propose a novel method based on a transfer learning method to extract the features of multisource images. First, the ResNet50 network is used to extract the initial features of the images. Owing to the problems of feature redundancy and fuzzy features in initial features, Spearman and zero phase component analysis can be used to achieve feature reduction and enhancement, which can further improve the computational efficiency and fusion accuracy in fusion. Finally, the fusion image is obtained using fusion rules that we designed based on the current state. The algorithm's reliability is tested using field data from the Iliamna Volcano. The case study demonstrates the effectiveness of the proposed strategy, which also offers a novel way to locate subsurface targets.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49135882","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}
Wireless Electromagnetic Method (WEM) is an emerging new method for deep resource exploration. This method based on Magnetotellurics and Controlled Source Electromagnetic Method features advantages such as high signal strength and signal-to-noise ratio, large penetration depth, and easy survey geometry setups, which gives WEM potential for deployment in mineral exploration of large depth. As for now, there is little research on the controlling factors of the ionosphere in WEM exploration and whether the ionosphere is related to the modeling result remains unclear. In this work, we first developed a modified Quadrature with Extrapolation method to settle the oscillation in the calculation of WEM response. Then we compared its performance and accuracy with other methods and found that our method has better numerical stability even with highly oscillated integral kernels, which is ideal for WEM emulation. With the emulation tools, we can further investigate how the ionosphere’s height and resistivity affect the ground-received signal. We compared signals obtained with different ionospheric properties under various earth resistivity models. The conclusion we got is that these ionospheric properties only impact the received signal’s strength and have no influence on the Cagniard resistivity and phase of impedance.
{"title":"A Study of Ionospheric Impacts in WEM Exploration with QWE Method","authors":"Yilang Zhang, Ya Gao, C. Fu","doi":"10.1093/jge/gxad015","DOIUrl":"https://doi.org/10.1093/jge/gxad015","url":null,"abstract":"\u0000 Wireless Electromagnetic Method (WEM) is an emerging new method for deep resource exploration. This method based on Magnetotellurics and Controlled Source Electromagnetic Method features advantages such as high signal strength and signal-to-noise ratio, large penetration depth, and easy survey geometry setups, which gives WEM potential for deployment in mineral exploration of large depth. As for now, there is little research on the controlling factors of the ionosphere in WEM exploration and whether the ionosphere is related to the modeling result remains unclear. In this work, we first developed a modified Quadrature with Extrapolation method to settle the oscillation in the calculation of WEM response. Then we compared its performance and accuracy with other methods and found that our method has better numerical stability even with highly oscillated integral kernels, which is ideal for WEM emulation. With the emulation tools, we can further investigate how the ionosphere’s height and resistivity affect the ground-received signal. We compared signals obtained with different ionospheric properties under various earth resistivity models. The conclusion we got is that these ionospheric properties only impact the received signal’s strength and have no influence on the Cagniard resistivity and phase of impedance.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49201589","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}
Hongzhi Chen, Jun-qiang Lu, X. Ju, Bai-yong Men, W. Qiao
Acoustoelectric logging is an important reservoir permeability evaluation method in the field of oil and gas exploration. Its complex composition, weak acoustoelectric signals, vulnerability to Electro Magnetic Interference, and other characteristics require high Electro Magnetic Compatibility. In this study, after systematically analysing the interference characteristics of the detector, the electromagnetic protection measures are found to be largely inadequate. A complete shielding of the transmitting acoustic system was proposed. The shielding effectiveness was calculated and tested. In the test, the shielding suppression was ineffective, and the interference was enhanced by 60 dB instead. The explanation of conducted interference was given, and the conducted interference simulation prediction model was established. The simulation result explains the experimental result well. According to the suppression measurements provided by the model, the conducted interference was effectively suppressed, making the shielding effect of the transmitting acoustic system meet the design requirements.
{"title":"Electromagnetic compatibility analysis and interference shielding method for AcoustoElectric Logging Tool 2.0","authors":"Hongzhi Chen, Jun-qiang Lu, X. Ju, Bai-yong Men, W. Qiao","doi":"10.1093/jge/gxad013","DOIUrl":"https://doi.org/10.1093/jge/gxad013","url":null,"abstract":"\u0000 Acoustoelectric logging is an important reservoir permeability evaluation method in the field of oil and gas exploration. Its complex composition, weak acoustoelectric signals, vulnerability to Electro Magnetic Interference, and other characteristics require high Electro Magnetic Compatibility. In this study, after systematically analysing the interference characteristics of the detector, the electromagnetic protection measures are found to be largely inadequate. A complete shielding of the transmitting acoustic system was proposed. The shielding effectiveness was calculated and tested. In the test, the shielding suppression was ineffective, and the interference was enhanced by 60 dB instead. The explanation of conducted interference was given, and the conducted interference simulation prediction model was established. The simulation result explains the experimental result well. According to the suppression measurements provided by the model, the conducted interference was effectively suppressed, making the shielding effect of the transmitting acoustic system meet the design requirements.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42371986","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}
Haidi Yang, L. Fu, Hongyang Li, Q. Du, Haochen Zheng
Seismic exploration of deep oil/gas reservoirs involves the propagation of seismic waves in high-pressure media. Traditional elastic wave equations are not suitable for describing such media. The theory of acoustoelasticity establishes the dynamic equation of wave propagating in prestressed media through constitutive relation using third-order elastic constants. Many studies have been carried out on numerical simulations for acoustoelastic waves, but mainly are limited to 2D cases. A standard staggered-grid (SSG) finite difference (FD) approach and the perfectly matched layer (PML) absorbing boundary are combined to solve 3D first-order velocity-stress equations of acoustoelasticity to simulate wave propagating in 3D prestressed solid medium. Our numerical results are partially validated by plane wave analytical solution through the comparison of calculated and theoretical P-/S-wave velocities as a function of confining prestress. We perform numerical simulations of acoustoelastic waves under confining, uniaxial, and pure shear prestressed conditions. The results show the stress-induced velocity anisotropy in acoustoelastic media, which is closely related to the direction of prestresses. Comparisons to seismic simulations based on the theory of elasticity illustrate the limitation of conventional elastic simulations for prestressed media. Numerical simulations prove the significant effect of prestressed conditions on seismic responses.
{"title":"3D acoustoelastic FD modeling of elastic wave propagation in prestressed solid media","authors":"Haidi Yang, L. Fu, Hongyang Li, Q. Du, Haochen Zheng","doi":"10.1093/jge/gxad010","DOIUrl":"https://doi.org/10.1093/jge/gxad010","url":null,"abstract":"\u0000 Seismic exploration of deep oil/gas reservoirs involves the propagation of seismic waves in high-pressure media. Traditional elastic wave equations are not suitable for describing such media. The theory of acoustoelasticity establishes the dynamic equation of wave propagating in prestressed media through constitutive relation using third-order elastic constants. Many studies have been carried out on numerical simulations for acoustoelastic waves, but mainly are limited to 2D cases. A standard staggered-grid (SSG) finite difference (FD) approach and the perfectly matched layer (PML) absorbing boundary are combined to solve 3D first-order velocity-stress equations of acoustoelasticity to simulate wave propagating in 3D prestressed solid medium. Our numerical results are partially validated by plane wave analytical solution through the comparison of calculated and theoretical P-/S-wave velocities as a function of confining prestress. We perform numerical simulations of acoustoelastic waves under confining, uniaxial, and pure shear prestressed conditions. The results show the stress-induced velocity anisotropy in acoustoelastic media, which is closely related to the direction of prestresses. Comparisons to seismic simulations based on the theory of elasticity illustrate the limitation of conventional elastic simulations for prestressed media. Numerical simulations prove the significant effect of prestressed conditions on seismic responses.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46104573","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}
Shuaishuai Li, Jiangjie Zhang, Q. Cheng, Feng Zhu, Linong Liu
With the development of seismic surveys and the decline of shallow petroleum resources, high resolution and high signal-to-noise ratio have become more important in seismic processing. To improve the quality of seismic data, stationary phase migration based on dip-angle gathers can be used to separate the reflected waves and noise. However, this method is very computationally intensive and heavily dependent on expert experience. Neural networks currently have powerful adaptive capabilities and great potential to replace artificial processing. Certain applications of convolution neural networks (CNNs) on stack profiles lead to a loss of amplitude information. Therefore, we have developed CNNs for noise reduction based on Common-Reflection-Point (CRP) gathers. We used CRP gathers of stationary phase migration as labels and CRP gathers of conventional prestack time migration as inputs. In addition, we analyzed the seismic amplitude properties and demonstrated the neural network optimization process and results. The results showed that our methods can achieve fast and reliable denoising and produce high-quality stack profiles that contain true amplitude information. Furthermore, the predicted high-quality CRP gathers can be used for further processing steps, such as normal moveout correction and amplitude variation with offset.
{"title":"Seismic profile denoising based on common-reflection-point gathers using convolution neural networks","authors":"Shuaishuai Li, Jiangjie Zhang, Q. Cheng, Feng Zhu, Linong Liu","doi":"10.1093/jge/gxad008","DOIUrl":"https://doi.org/10.1093/jge/gxad008","url":null,"abstract":"With the development of seismic surveys and the decline of shallow petroleum resources, high resolution and high signal-to-noise ratio have become more important in seismic processing. To improve the quality of seismic data, stationary phase migration based on dip-angle gathers can be used to separate the reflected waves and noise. However, this method is very computationally intensive and heavily dependent on expert experience. Neural networks currently have powerful adaptive capabilities and great potential to replace artificial processing. Certain applications of convolution neural networks (CNNs) on stack profiles lead to a loss of amplitude information. Therefore, we have developed CNNs for noise reduction based on Common-Reflection-Point (CRP) gathers. We used CRP gathers of stationary phase migration as labels and CRP gathers of conventional prestack time migration as inputs. In addition, we analyzed the seismic amplitude properties and demonstrated the neural network optimization process and results. The results showed that our methods can achieve fast and reliable denoising and produce high-quality stack profiles that contain true amplitude information. Furthermore, the predicted high-quality CRP gathers can be used for further processing steps, such as normal moveout correction and amplitude variation with offset.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41567527","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 Paleogene Shahejie and Dongying formations of the eastern Bohai Bay Basin contain over 500m fluvial-deltaic deposits and over 600 m deltaic-lacustrine deposits, both of which are important for oil and gas exploration. This study aims to figure out the deposition system distribution within the sequence stratigraphy and predict the exploration target. Sequence boundaries are recognized by unconformities in the seismic profiles and abrupt changes in the well-logging curves (AC, SP, GR, Rt), and two 2nd order sequences and five 3rd order sequences (SQs1, SQs3 in Shahejie Formation and SQd1-SQd3 in Dongying Formation) are identified. Four types of depositional system and its distribution is determined by well-logging profiles, cores, relative sand content, and root-mean-square seismic attributes. The SQs3 sequence is dominantly by fan deltas and lacustrine deposits, the SQs1 sequence is dominantly by shallow lacustrine deposits, the SQd3 sequence is dominantly by braided-river delta, semi-deep lacustrine, and turbidite fan, the SQd2 sequence is dominantly by braided-river delta deposits, whereas the SQd1 sequence is dominantly by braided-river deposits. The controlling factors are determined by basin subsidence simulation and fossil data of biological palynology, indicating that tectonic activity is the main controlling factor in SQs3 and SQd3 while climate is the main controlling factor in the SQs1, SQd2 and SQd1 sequences. Combined with the physical properties of sandstone, it is concluded that the beach bar in the SQs1 sequence, turbidite fan in the SQs3 and SQd3 sequences, and thick sandstone in the SQd2 sequence are the important exploration targets.
{"title":"Sequence architecture, depositional system evolution and controlling factors in a lacustrine basin: A case study from Changdi Area, Bohai Bay Basin, Eastern China","authors":"Yuhan Cheng, Zhiwei Wang, Jingyan Liu, Q. Wu, Shina Yu, Xiao Ma, Dingliang Peng, Yiyao Zhang","doi":"10.1093/jge/gxad007","DOIUrl":"https://doi.org/10.1093/jge/gxad007","url":null,"abstract":"\u0000 The Paleogene Shahejie and Dongying formations of the eastern Bohai Bay Basin contain over 500m fluvial-deltaic deposits and over 600 m deltaic-lacustrine deposits, both of which are important for oil and gas exploration. This study aims to figure out the deposition system distribution within the sequence stratigraphy and predict the exploration target. Sequence boundaries are recognized by unconformities in the seismic profiles and abrupt changes in the well-logging curves (AC, SP, GR, Rt), and two 2nd order sequences and five 3rd order sequences (SQs1, SQs3 in Shahejie Formation and SQd1-SQd3 in Dongying Formation) are identified. Four types of depositional system and its distribution is determined by well-logging profiles, cores, relative sand content, and root-mean-square seismic attributes. The SQs3 sequence is dominantly by fan deltas and lacustrine deposits, the SQs1 sequence is dominantly by shallow lacustrine deposits, the SQd3 sequence is dominantly by braided-river delta, semi-deep lacustrine, and turbidite fan, the SQd2 sequence is dominantly by braided-river delta deposits, whereas the SQd1 sequence is dominantly by braided-river deposits. The controlling factors are determined by basin subsidence simulation and fossil data of biological palynology, indicating that tectonic activity is the main controlling factor in SQs3 and SQd3 while climate is the main controlling factor in the SQs1, SQd2 and SQd1 sequences. Combined with the physical properties of sandstone, it is concluded that the beach bar in the SQs1 sequence, turbidite fan in the SQs3 and SQd3 sequences, and thick sandstone in the SQd2 sequence are the important exploration targets.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46471929","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 estimation of physical and anisotropic parameters is of great importance for the characterisation of characterizing fractured reservoirs. Vertical fractures developing in a laterally isotropic (VTI) setting are equivalent to orthotropic anisotropic (OA) media common in stratified fractured shale reservoirs. To obtain independent anisotropic and physical information, a novel reflection coefficient approximation containing physical and anisotropic parameters is derived to improve the stability of the inversion for orthotropic media. To simplify the equation for the reflection coefficient, an approximate rock physics model is constructed using the approximate theory of rock modulus. The estimated parameters are reduced from nine to six. The accuracy analysis reveals that the new reflection coefficient is appropriate and suitable for inversion. In addition, a stepwise Bayesian AVAZ inversion method with smooth background constraints is developed to estimate the anisotropic and physical parameters from the azimuthal seismic data. The smooth background constraint improves the robustness of the inversion. And the stepwise inversion strategy solves the problem that the contribution of the fracture parameter to the reflection coefficient is smaller than the other parameters. Synthetic cases show that the proposed stepwise Bayesian AVAZ inversion method is feasible in estimating the anisotropic parameters for OA media even when the signal-to-noise ratio is 2. The field cases show that the proposed inversion method has good stability and robustness in predicting shale reservoirs with vertical or near-vertical fractures.
{"title":"Seismic pre-stack inversion for physical and anisotropic parameters in fractured shale reservoirs","authors":"Si-Yi Wu, Z. Zong","doi":"10.1093/jge/gxad009","DOIUrl":"https://doi.org/10.1093/jge/gxad009","url":null,"abstract":"\u0000 The estimation of physical and anisotropic parameters is of great importance for the characterisation of characterizing fractured reservoirs. Vertical fractures developing in a laterally isotropic (VTI) setting are equivalent to orthotropic anisotropic (OA) media common in stratified fractured shale reservoirs. To obtain independent anisotropic and physical information, a novel reflection coefficient approximation containing physical and anisotropic parameters is derived to improve the stability of the inversion for orthotropic media. To simplify the equation for the reflection coefficient, an approximate rock physics model is constructed using the approximate theory of rock modulus. The estimated parameters are reduced from nine to six. The accuracy analysis reveals that the new reflection coefficient is appropriate and suitable for inversion. In addition, a stepwise Bayesian AVAZ inversion method with smooth background constraints is developed to estimate the anisotropic and physical parameters from the azimuthal seismic data. The smooth background constraint improves the robustness of the inversion. And the stepwise inversion strategy solves the problem that the contribution of the fracture parameter to the reflection coefficient is smaller than the other parameters. Synthetic cases show that the proposed stepwise Bayesian AVAZ inversion method is feasible in estimating the anisotropic parameters for OA media even when the signal-to-noise ratio is 2. The field cases show that the proposed inversion method has good stability and robustness in predicting shale reservoirs with vertical or near-vertical fractures.","PeriodicalId":54820,"journal":{"name":"Journal of Geophysics and Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49644694","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}
Shiqi Liu, Y. Fei, Juan Wang, Di Wu, Dongyu Guo, Yanlin Dong, Xingjie Liu, Yiwei Shangguan
Reducing the width of safe coal pillar near geological structures, such as a water-conducting fault, to improve the extraction ratio of coal seam is a major concern that needs to be addressed urgently for mining shallow coal resources in China. To tackle the contradiction between improving the extraction ratio of resources and the disaster caused by reducing the width of the waterproof coal pillar, this study focuses on retaining the coal (rock) pillar near the water-conducting fault and proposes a novel method for calculating the waterproofing of the coal pillar precisely. We consider the different location relationships between the water-conducting fault, confined aquifer and coal seam, and suggest the principle of retaining the waterproofing of the coal pillar. First, we develop a mechanical model describing a waterproof coal pillar near the water-conducting fault by using elastic–plastic mechanics theory and subsequently calculate the length of plastic zone of the coal pillar under water pressure of the fault by using the limit equilibrium method. Furthermore, we use FLAC3D software to simulate the stress distribution of the coal seam roof and floor under fault water pressure. Subsequently, based on the Mohr–Coulomb strength criterion, we propose a method to calculate the width of waterproof coal pillars by combining the plastic zone with the maximum principal stress propagation line. Ultimately, we assess and discuss the accuracy and simplicity of this method by combining it with engineering methods.
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