{"title":"水体测量中二维和三维电阻率数据的反演","authors":"M. Loke, T. Dahlin, D. Rucker","doi":"10.3997/2214-4609.201900401","DOIUrl":null,"url":null,"abstract":"Resistivity surveys are now also carried in areas covered by water. The surveys involve electrodes planted on the water bottom or on a streamer towed by a boat. As the water layer has a large effect on resistivity measurements, its effect must be accurately modelled. The water resistivity and depth to the bottom are usually independently measured with a conductivity meter and depth sounder. The upper part of a finite-element grid is used to model the water layer, including possible variations in the water resistivity with depth. We show the results from a 2-D survey in Stockholm with electrodes planted on the sea bottom. The sediment thickness from the inverse model agrees well with drilling results and a possible weak zone in the bedrock was detected. Surveys with floating electrodes do not follow a straight line due to water currents and a 3-D inversion approach is required. An example is shown from a survey in the Panama Canal where the data from 19 sub-parallel lines are collated into a 3-D data set. The inverse model shows a conductive bottom with weathered marine sedimentary rocks and a remnant of an old river channel filled with more resistive sands and gravels.","PeriodicalId":393867,"journal":{"name":"EAGE-GSM 2nd Asia Pacific Meeting on Near Surface Geoscience and Engineering","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2019-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":"{\"title\":\"The inversion of 2-D and 3-D resistivity data from surveys in aquatic areas\",\"authors\":\"M. Loke, T. Dahlin, D. Rucker\",\"doi\":\"10.3997/2214-4609.201900401\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Resistivity surveys are now also carried in areas covered by water. The surveys involve electrodes planted on the water bottom or on a streamer towed by a boat. As the water layer has a large effect on resistivity measurements, its effect must be accurately modelled. The water resistivity and depth to the bottom are usually independently measured with a conductivity meter and depth sounder. The upper part of a finite-element grid is used to model the water layer, including possible variations in the water resistivity with depth. We show the results from a 2-D survey in Stockholm with electrodes planted on the sea bottom. The sediment thickness from the inverse model agrees well with drilling results and a possible weak zone in the bedrock was detected. Surveys with floating electrodes do not follow a straight line due to water currents and a 3-D inversion approach is required. An example is shown from a survey in the Panama Canal where the data from 19 sub-parallel lines are collated into a 3-D data set. The inverse model shows a conductive bottom with weathered marine sedimentary rocks and a remnant of an old river channel filled with more resistive sands and gravels.\",\"PeriodicalId\":393867,\"journal\":{\"name\":\"EAGE-GSM 2nd Asia Pacific Meeting on Near Surface Geoscience and Engineering\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2019-04-24\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"2\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"EAGE-GSM 2nd Asia Pacific Meeting on Near Surface Geoscience and Engineering\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.3997/2214-4609.201900401\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"EAGE-GSM 2nd Asia Pacific Meeting on Near Surface Geoscience and Engineering","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3997/2214-4609.201900401","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
The inversion of 2-D and 3-D resistivity data from surveys in aquatic areas
Resistivity surveys are now also carried in areas covered by water. The surveys involve electrodes planted on the water bottom or on a streamer towed by a boat. As the water layer has a large effect on resistivity measurements, its effect must be accurately modelled. The water resistivity and depth to the bottom are usually independently measured with a conductivity meter and depth sounder. The upper part of a finite-element grid is used to model the water layer, including possible variations in the water resistivity with depth. We show the results from a 2-D survey in Stockholm with electrodes planted on the sea bottom. The sediment thickness from the inverse model agrees well with drilling results and a possible weak zone in the bedrock was detected. Surveys with floating electrodes do not follow a straight line due to water currents and a 3-D inversion approach is required. An example is shown from a survey in the Panama Canal where the data from 19 sub-parallel lines are collated into a 3-D data set. The inverse model shows a conductive bottom with weathered marine sedimentary rocks and a remnant of an old river channel filled with more resistive sands and gravels.