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A method for calculating the P-to-S-wave velocity ratio through direct inversion of prestack multi-component seismic data based on the L1-2 norm constraint |
HAN Lei1( ), LI Jing-Ye1, GENG Wei-Heng2, WANG Yong-Ping1, YANG Qi-Yu1, ZHANG Yu-Ning1 |
1. College of Geophysics,China University of Petroleum(Beijing),Beijing 102249,China 2. School of Information Science and Technology,Tsinghua University,Beijing 100084,China |
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Abstract The ratio of compressional to shear wave velocities(hereafter referred to as the P-to-S-wave velocity ratio) is an essential parameter for lithology discrimination,reservoir characterization,and gas reservoir identification.Direct inversion of PP-wave seismic data to derive the P- and S-wave velocities has been a well-established technique.However,calculating the P-to-S-wave velocity ratio using the P- and S-wave velocities obtained through individual inversion may lead to cumulative errors.In contrast,since PS-wave data inherently contain S-wave velocity information,the joint inversion of PS-wave data can significantly improve the accuracy of the P-to-S-wave velocity ratio.This study employed the L1-2 norm to enhance the resolution of inversion results.Compared to the L1 and L2 norms,the L1-2 norm yielded sparser solutions with higher resolution.First,this study derived and assessed the accuracy of linearized forward modeling approximate formulas for PP- and PS-waves.Second,based on Bayesian theory,this study incorporated the L1-2 norm to construct an objective function for the direct inversion of the P-to-S-wave velocity ratio.Third,the objective function was solved to obtain the inversion result for the P-to-S-wave velocity ratio.The quantitative comparison of the correlation coefficients demonstrates that the inversion results based on the L1-2 norm outperform those based on the L1 or L2 norm,direct inversion is superior to indirect inversion,and joint inversion provides better results than individual inversion.Finally, the effectiveness and feasibility of the proposed method in this study were validated through inversions of synthetic and field data.
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Received: 25 October 2024
Published: 22 July 2025
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Direct inversion of P-wave velocity (a), S-wave velocity (b) and density (c) by PP and PP-PS wave
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数据类型 | 单独PP反演 | 联合PP+PS联合反演 | 反演参数 | 纵波速度 | 横波速度 | 密度 | 纵波速度 | 横波速度 | 密度 | 相关系数 | 0.8723 | 0.8259 | 0.9067 | 0.9423 | 0.8697 | 0.9619 |
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Correlation coefficients of inversion results of different data types m/s
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地层 | Vp/(m·s-1) | Vs/(m·s-1) | ρ/(g·cm-3) | 页岩 | 2540 | 1250 | 2.30 | 含气砂岩 | 2980 | 1525 | 2.42 |
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The first type of typical AVO model
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地层 | Vp/(m·s-1) | Vs/(m·s-1) | ρ/(g·cm-3) | 页岩 | 2776 | 1780 | 2.35 | 含气砂岩 | 2700 | 1740 | 2.34 |
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The second type of typical AVO model
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地层 | Vp/(m·s -1) | Vs/(m·s-1) | ρ/(g·cm-3) | 页岩 | 3000 | 1280 | 2.30 | 含气砂岩 | 2450 | 1265 | 2.12 |
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The third type of typical AVO model
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Comparison of PP wave reflection coefficients of three typical AVO models
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Comparison of PS wave reflection coefficients of three typical AVO models
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Noise-free forward-modeled PP-wave(a) and PS-wave(b) seismic records
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Comparison of one-dimensional probability density functions with different distributions
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Two-dimensional images of L0 norm (a), L1 norm (b), L2 norm (c), and L1-2 norm (d)
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Noise-free data inversion results a—PP only inversion;b—PP+PS joint inversion
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Forward modeling synthetic seismic record with SNR=10 a—PP wave seismic record;b—PS wave seismic record
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SNR=10 data inversion results a—PP only inversion;b—PP+PS joint inversion
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Forward modeling synthetic seismic record with SNR=4 a—PP wave seismic record;b—PS wave seismic record
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| 联合PP+PS直接反演 | 单独PP直接反演 | 联合PP+PS间接反演 | L1 | L2 | L1-2 | L1 | L2 | L1-2 | L1 | L2 | L1-2 | SNR=4 | 0.9326 | 0.9300 | 0.9592 | 0.9123 | 0.9050 | 0.9454 | 0.9073 | 0.9017 | 0.9342 | SNR=10 | 0.9815 | 0.9529 | 0.9841 | 0.9257 | 0.9228 | 0.9536 | 0.9219 | 0.9162 | 0.9425 |
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Comparison of correlation coefficients of inversion results
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SNR=4 data inversion results a—PP only inversion;b—PP+PS joint inversion
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PP only inversion results with SNR=10(a) and SNR=4(b) data
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Part-stack seismic profile of PP waves(a) and PS waves(b)
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Comparison between offset well log inversion results inversion results of PP waves alone(a) joint inversion results of PP-PS waves(b)
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Direct inversion of P-to-S wave velocity ratio using L1-2 norm constraint for single PP waves seismic data
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Direct inversion of P-to-S wave velocity ratio using L1-2 norm constraint for joint PP waves and PS waves seismic data
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数据类型 | 单独PP反演 | 联合PP+PS联合反演 | 约束方法 | L1范数 | L2范数 | L1-2范数 | L1范数 | L2范数 | L1-2范数 | 相关系数 | 0.3133 | 0.3019 | 0.5350 | 0.4514 | 0.4359 | 0.6535 |
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Comparison of correlation coefficients of inversion results
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