Joint Inversion of Ground-Penetrating Radar and Seismic Velocities for Porosity and Water Saturation in Shallow Sediments

Abdullatif A. Al-Shuhail, Ademola Adetunji

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Ground-penetrating radar (GPR) measures the velocity (VG) of electromagnetic waves in a subsurface material. In a low-loss material, VG depends primarily on the porosity (ρ) and water saturation (Sw) of the material. Therefore, it is impossible to estimate ρ and Sw uniquely from VG without additional information. The seismic P-wave velocity (VP) in the same material can provide the extra information required for the inversion. In this study, an approach is described for a closed-form solution of VG and VP to invert for ρ and Sw in shallow sediments. The complex refractive index model (CRIM) for VG and Gassmann-Biot model for VP are used to relate these velocities to ρ and Sw. Each model presents a nonlinear equation in ρ and Sw. The two equations are solved simultaneously to estimate ρ and Sw from VG-VP measurements. Testing of the inversion procedure in the presence of errors in assuming the properties of the soil matrix showed that these errors can drastically affect the inverted water saturation and porosity, especially in dry, low-porosity sediments. The approach is applied on many VG-VP measurements in various soil types collected from the literature. Inversion results show that inverted ρ values for most data points fell around 0.4, which is the critical porosity in sandy soils, while inverted Sw values generally agreed with reported saturations for most of the data points. Few data points resulted in unrealistic ρ and Sw values when a sandy soil matrix was assumed. We found that perturbing the matrix properties for these points resulted in shifting the inverted ρ and Sw to more realistic values.

Original languageEnglish
Pages (from-to)105-119
Number of pages15
JournalJournal of Environmental and Engineering Geophysics
Volume21
Issue number3
DOIs
Publication statusPublished - Sep 1 2016

Fingerprint

ground penetrating radar
seismic velocity
soils
Sediments
sediments
Radar
Porosity
porosity
saturation
inversions
Soils
sandy soil
sediment
water
matrix
Water
matrices
electromagnetic wave
refractive index
estimates

ASJC Scopus subject areas

  • Environmental Engineering
  • Geotechnical Engineering and Engineering Geology
  • Geophysics

Cite this

@article{15cc2cb392ae4c3d98b1afc5952ccccb,
title = "Joint Inversion of Ground-Penetrating Radar and Seismic Velocities for Porosity and Water Saturation in Shallow Sediments",
abstract = "Ground-penetrating radar (GPR) measures the velocity (VG) of electromagnetic waves in a subsurface material. In a low-loss material, VG depends primarily on the porosity (ρ) and water saturation (Sw) of the material. Therefore, it is impossible to estimate ρ and Sw uniquely from VG without additional information. The seismic P-wave velocity (VP) in the same material can provide the extra information required for the inversion. In this study, an approach is described for a closed-form solution of VG and VP to invert for ρ and Sw in shallow sediments. The complex refractive index model (CRIM) for VG and Gassmann-Biot model for VP are used to relate these velocities to ρ and Sw. Each model presents a nonlinear equation in ρ and Sw. The two equations are solved simultaneously to estimate ρ and Sw from VG-VP measurements. Testing of the inversion procedure in the presence of errors in assuming the properties of the soil matrix showed that these errors can drastically affect the inverted water saturation and porosity, especially in dry, low-porosity sediments. The approach is applied on many VG-VP measurements in various soil types collected from the literature. Inversion results show that inverted ρ values for most data points fell around 0.4, which is the critical porosity in sandy soils, while inverted Sw values generally agreed with reported saturations for most of the data points. Few data points resulted in unrealistic ρ and Sw values when a sandy soil matrix was assumed. We found that perturbing the matrix properties for these points resulted in shifting the inverted ρ and Sw to more realistic values.",
author = "Al-Shuhail, {Abdullatif A.} and Ademola Adetunji",
year = "2016",
month = "9",
day = "1",
doi = "10.2113/JEEG21.3.105",
language = "English",
volume = "21",
pages = "105--119",
journal = "Journal of Environmental and Engineering Geophysics",
issn = "1083-1363",
publisher = "Environmental and Engineering Geophysical Society (EEGS)",
number = "3",

}

TY - JOUR

T1 - Joint Inversion of Ground-Penetrating Radar and Seismic Velocities for Porosity and Water Saturation in Shallow Sediments

AU - Al-Shuhail, Abdullatif A.

AU - Adetunji, Ademola

PY - 2016/9/1

Y1 - 2016/9/1

N2 - Ground-penetrating radar (GPR) measures the velocity (VG) of electromagnetic waves in a subsurface material. In a low-loss material, VG depends primarily on the porosity (ρ) and water saturation (Sw) of the material. Therefore, it is impossible to estimate ρ and Sw uniquely from VG without additional information. The seismic P-wave velocity (VP) in the same material can provide the extra information required for the inversion. In this study, an approach is described for a closed-form solution of VG and VP to invert for ρ and Sw in shallow sediments. The complex refractive index model (CRIM) for VG and Gassmann-Biot model for VP are used to relate these velocities to ρ and Sw. Each model presents a nonlinear equation in ρ and Sw. The two equations are solved simultaneously to estimate ρ and Sw from VG-VP measurements. Testing of the inversion procedure in the presence of errors in assuming the properties of the soil matrix showed that these errors can drastically affect the inverted water saturation and porosity, especially in dry, low-porosity sediments. The approach is applied on many VG-VP measurements in various soil types collected from the literature. Inversion results show that inverted ρ values for most data points fell around 0.4, which is the critical porosity in sandy soils, while inverted Sw values generally agreed with reported saturations for most of the data points. Few data points resulted in unrealistic ρ and Sw values when a sandy soil matrix was assumed. We found that perturbing the matrix properties for these points resulted in shifting the inverted ρ and Sw to more realistic values.

AB - Ground-penetrating radar (GPR) measures the velocity (VG) of electromagnetic waves in a subsurface material. In a low-loss material, VG depends primarily on the porosity (ρ) and water saturation (Sw) of the material. Therefore, it is impossible to estimate ρ and Sw uniquely from VG without additional information. The seismic P-wave velocity (VP) in the same material can provide the extra information required for the inversion. In this study, an approach is described for a closed-form solution of VG and VP to invert for ρ and Sw in shallow sediments. The complex refractive index model (CRIM) for VG and Gassmann-Biot model for VP are used to relate these velocities to ρ and Sw. Each model presents a nonlinear equation in ρ and Sw. The two equations are solved simultaneously to estimate ρ and Sw from VG-VP measurements. Testing of the inversion procedure in the presence of errors in assuming the properties of the soil matrix showed that these errors can drastically affect the inverted water saturation and porosity, especially in dry, low-porosity sediments. The approach is applied on many VG-VP measurements in various soil types collected from the literature. Inversion results show that inverted ρ values for most data points fell around 0.4, which is the critical porosity in sandy soils, while inverted Sw values generally agreed with reported saturations for most of the data points. Few data points resulted in unrealistic ρ and Sw values when a sandy soil matrix was assumed. We found that perturbing the matrix properties for these points resulted in shifting the inverted ρ and Sw to more realistic values.

UR - http://www.scopus.com/inward/record.url?scp=84989874083&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84989874083&partnerID=8YFLogxK

U2 - 10.2113/JEEG21.3.105

DO - 10.2113/JEEG21.3.105

M3 - Article

VL - 21

SP - 105

EP - 119

JO - Journal of Environmental and Engineering Geophysics

JF - Journal of Environmental and Engineering Geophysics

SN - 1083-1363

IS - 3

ER -