{"title":"倾斜横向各向同性介质的弹性全波形反演:考虑对称轴倾斜角的多步骤策略","authors":"Hengli Song, Yuzhu Liu, Jizhong Yang","doi":"10.1111/1365-2478.13578","DOIUrl":null,"url":null,"abstract":"<p>Transversely isotropic media with a tilted symmetry axis (TTI) exits widely underground due to tectonic movement and mineral orientation. Traditional full waveform inversion (FWI) based on isotropic media or transversely isotropic media with a vertical symmetry axis (VTI) cannot deal with such situations. To address this limitation, TTI–based FWI was developed. However, its practical application faces challenges in estimating the symmetry axis tilt angle <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math>. Previous studies have generally assumed that <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math> is equal to the strata dip angle, which is incorrect in complex structures such as salt domes and magmatic intrusion zones. Another theoretically robust way to estimate <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math> is to treat it as the parameter to be inverted, but there are still some problems unresolved. First, the parameter <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math> increases the nonlinearity of the inversion process, and its impact mechanism on inversion is not yet clear. Second, there is severe crosstalk (also known as trade-off or coupling) between parameters, but the current parameter decoupling technique for TTI–based FWI is not mature. To address the first problem, we assess the interaction between <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math> and other parameters by analysing the radiation patterns in the TTI background. Our analysis reveals that <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math> is most coupled by S-wave vertical velocity <span></span><math>\n <semantics>\n <msub>\n <mi>v</mi>\n <mrow>\n <mi>s</mi>\n <mn>0</mn>\n </mrow>\n </msub>\n <annotation>${{v}_{{\\mathrm{s}}0}}$</annotation>\n </semantics></math>, and <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math> substantially affects anisotropic parameters <span></span><math>\n <semantics>\n <mi>ε</mi>\n <annotation>$\\varepsilon $</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mi>δ</mi>\n <annotation>$\\delta $</annotation>\n </semantics></math>. Therefore, we conclude that a good inversion of velocity parameters is a prerequisite for recovering <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math>, and only after <span></span><math>\n <semantics>\n <msub>\n <mi>θ</mi>\n <mi>t</mi>\n </msub>\n <annotation>${{\\theta }_{\\mathrm{t}}}$</annotation>\n </semantics></math> recovers can <span></span><math>\n <semantics>\n <mi>ε</mi>\n <annotation>$\\varepsilon $</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mi>δ</mi>\n <annotation>$\\delta $</annotation>\n </semantics></math> be recovered. This conclusion provides a natural perspective for solving the second problem. We therefore propose a multi-step and multi-parameter joint inversion strategy to gradually improve the quality of parameter inversion and weaken their coupling. Numerical experiments demonstrate that our strategy achieves more accurate inversion results compared to previously proposed multi-parameter inversion strategies. Finally, the application to the field OBN dataset acquired from the South China Sea verifies the practicality of our method.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":null,"pages":null},"PeriodicalIF":1.8000,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Elastic full waveform inversion for tilted transverse isotropic media: A multi-step strategy accounting for a symmetry axis tilt angle\",\"authors\":\"Hengli Song, Yuzhu Liu, Jizhong Yang\",\"doi\":\"10.1111/1365-2478.13578\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Transversely isotropic media with a tilted symmetry axis (TTI) exits widely underground due to tectonic movement and mineral orientation. Traditional full waveform inversion (FWI) based on isotropic media or transversely isotropic media with a vertical symmetry axis (VTI) cannot deal with such situations. To address this limitation, TTI–based FWI was developed. However, its practical application faces challenges in estimating the symmetry axis tilt angle <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math>. Previous studies have generally assumed that <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math> is equal to the strata dip angle, which is incorrect in complex structures such as salt domes and magmatic intrusion zones. Another theoretically robust way to estimate <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math> is to treat it as the parameter to be inverted, but there are still some problems unresolved. First, the parameter <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math> increases the nonlinearity of the inversion process, and its impact mechanism on inversion is not yet clear. Second, there is severe crosstalk (also known as trade-off or coupling) between parameters, but the current parameter decoupling technique for TTI–based FWI is not mature. To address the first problem, we assess the interaction between <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math> and other parameters by analysing the radiation patterns in the TTI background. Our analysis reveals that <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math> is most coupled by S-wave vertical velocity <span></span><math>\\n <semantics>\\n <msub>\\n <mi>v</mi>\\n <mrow>\\n <mi>s</mi>\\n <mn>0</mn>\\n </mrow>\\n </msub>\\n <annotation>${{v}_{{\\\\mathrm{s}}0}}$</annotation>\\n </semantics></math>, and <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math> substantially affects anisotropic parameters <span></span><math>\\n <semantics>\\n <mi>ε</mi>\\n <annotation>$\\\\varepsilon $</annotation>\\n </semantics></math> and <span></span><math>\\n <semantics>\\n <mi>δ</mi>\\n <annotation>$\\\\delta $</annotation>\\n </semantics></math>. Therefore, we conclude that a good inversion of velocity parameters is a prerequisite for recovering <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math>, and only after <span></span><math>\\n <semantics>\\n <msub>\\n <mi>θ</mi>\\n <mi>t</mi>\\n </msub>\\n <annotation>${{\\\\theta }_{\\\\mathrm{t}}}$</annotation>\\n </semantics></math> recovers can <span></span><math>\\n <semantics>\\n <mi>ε</mi>\\n <annotation>$\\\\varepsilon $</annotation>\\n </semantics></math> and <span></span><math>\\n <semantics>\\n <mi>δ</mi>\\n <annotation>$\\\\delta $</annotation>\\n </semantics></math> be recovered. This conclusion provides a natural perspective for solving the second problem. We therefore propose a multi-step and multi-parameter joint inversion strategy to gradually improve the quality of parameter inversion and weaken their coupling. Numerical experiments demonstrate that our strategy achieves more accurate inversion results compared to previously proposed multi-parameter inversion strategies. Finally, the application to the field OBN dataset acquired from the South China Sea verifies the practicality of our method.</p>\",\"PeriodicalId\":12793,\"journal\":{\"name\":\"Geophysical Prospecting\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.8000,\"publicationDate\":\"2024-07-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Geophysical Prospecting\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1111/1365-2478.13578\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geophysical Prospecting","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/1365-2478.13578","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Elastic full waveform inversion for tilted transverse isotropic media: A multi-step strategy accounting for a symmetry axis tilt angle
Transversely isotropic media with a tilted symmetry axis (TTI) exits widely underground due to tectonic movement and mineral orientation. Traditional full waveform inversion (FWI) based on isotropic media or transversely isotropic media with a vertical symmetry axis (VTI) cannot deal with such situations. To address this limitation, TTI–based FWI was developed. However, its practical application faces challenges in estimating the symmetry axis tilt angle . Previous studies have generally assumed that is equal to the strata dip angle, which is incorrect in complex structures such as salt domes and magmatic intrusion zones. Another theoretically robust way to estimate is to treat it as the parameter to be inverted, but there are still some problems unresolved. First, the parameter increases the nonlinearity of the inversion process, and its impact mechanism on inversion is not yet clear. Second, there is severe crosstalk (also known as trade-off or coupling) between parameters, but the current parameter decoupling technique for TTI–based FWI is not mature. To address the first problem, we assess the interaction between and other parameters by analysing the radiation patterns in the TTI background. Our analysis reveals that is most coupled by S-wave vertical velocity , and substantially affects anisotropic parameters and . Therefore, we conclude that a good inversion of velocity parameters is a prerequisite for recovering , and only after recovers can and be recovered. This conclusion provides a natural perspective for solving the second problem. We therefore propose a multi-step and multi-parameter joint inversion strategy to gradually improve the quality of parameter inversion and weaken their coupling. Numerical experiments demonstrate that our strategy achieves more accurate inversion results compared to previously proposed multi-parameter inversion strategies. Finally, the application to the field OBN dataset acquired from the South China Sea verifies the practicality of our method.
期刊介绍:
Geophysical Prospecting publishes the best in primary research on the science of geophysics as it applies to the exploration, evaluation and extraction of earth resources. Drawing heavily on contributions from researchers in the oil and mineral exploration industries, the journal has a very practical slant. Although the journal provides a valuable forum for communication among workers in these fields, it is also ideally suited to researchers in academic geophysics.