{"title":"Analysis of subsurface velocity using CMP gathers picked up by unshielded GPR system: results from an experimental NAPL contaminated test site","authors":"Ibrar Iqbal, Bin Xiong, G. Tian, Yu Lu, Yang Yang","doi":"10.1080/08123985.2022.2131390","DOIUrl":null,"url":null,"abstract":"Adequate knowledge of velocity is required for accurate data imaging and depth conversion, as well as for quantifying the distribution of soil water content. Without complementary borehole information in the form of dielectric permittivity and/or porosity logs along the profile, it is currently impossible to reliably estimate the high-frequency electromagnetic velocity distribution in the probed subsurface region. Here, we present a new method for calculating the precise subsurface velocity structure from ground penetrating radar (GPR) reflection data that does not require boreholes or log data. This study investigates the ability of the pulse_EKKO PRO GPR system to predict a vertical profile for the possible velocity estimation of a layered and contaminated geophysical test site in Hangzhou, China. All data were acquired and saved on the GPR system in various files (projects) before analysis using GPR software to obtain approximated velocity modelling using common midpoint (CMP) gathers. Using the velocity spectrum analysis, a vertical profile of the interval velocities can be derived from each CMP gather. The findings of this study indicate that the proposed method is effective and sustainable. Furthermore, owing to the efficacy of the method in terms of field effort and computational complexity, it can easily be expanded to 3D GPR velocity exploration, increasing its importance in comparison to standard offset-based techniques for estimating velocity using GPR.","PeriodicalId":50460,"journal":{"name":"Exploration Geophysics","volume":"54 1","pages":"261 - 270"},"PeriodicalIF":0.6000,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Exploration Geophysics","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1080/08123985.2022.2131390","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Adequate knowledge of velocity is required for accurate data imaging and depth conversion, as well as for quantifying the distribution of soil water content. Without complementary borehole information in the form of dielectric permittivity and/or porosity logs along the profile, it is currently impossible to reliably estimate the high-frequency electromagnetic velocity distribution in the probed subsurface region. Here, we present a new method for calculating the precise subsurface velocity structure from ground penetrating radar (GPR) reflection data that does not require boreholes or log data. This study investigates the ability of the pulse_EKKO PRO GPR system to predict a vertical profile for the possible velocity estimation of a layered and contaminated geophysical test site in Hangzhou, China. All data were acquired and saved on the GPR system in various files (projects) before analysis using GPR software to obtain approximated velocity modelling using common midpoint (CMP) gathers. Using the velocity spectrum analysis, a vertical profile of the interval velocities can be derived from each CMP gather. The findings of this study indicate that the proposed method is effective and sustainable. Furthermore, owing to the efficacy of the method in terms of field effort and computational complexity, it can easily be expanded to 3D GPR velocity exploration, increasing its importance in comparison to standard offset-based techniques for estimating velocity using GPR.
期刊介绍:
Exploration Geophysics is published on behalf of the Australian Society of Exploration Geophysicists (ASEG), Society of Exploration Geophysics of Japan (SEGJ), and Korean Society of Earth and Exploration Geophysicists (KSEG).
The journal presents significant case histories, advances in data interpretation, and theoretical developments resulting from original research in exploration and applied geophysics. Papers that may have implications for field practice in Australia, even if they report work from other continents, will be welcome. ´Exploration and applied geophysics´ will be interpreted broadly by the editors, so that geotechnical and environmental studies are by no means precluded.
Papers are expected to be of a high standard. Exploration Geophysics uses an international pool of reviewers drawn from industry and academic authorities as selected by the editorial panel.
The journal provides a common meeting ground for geophysicists active in either field studies or basic research.