INVESTIGADORES
OSELLA Ana Maria
artículos
Título:
Fresnel reflection coefficients for GPR-AVO analysis and detection of seawater and NAPL contaminants
Autor/es:
CARCIONE, JOSÉ; GEI, DAVIDE; BOTELHO, MARCO; OSELLA, ANA; DE LA VEGA, MATIAS
Revista:
NEAR SURFACE GEOPHYSICS
Editorial:
EAGE
Referencias:
Año: 2006 vol. 4 p. 253 - 264
ISSN:
1569-4445
Resumen:
We obtain the TE (tranverse Electric) and TM (transverse Magnetic) Fresnel reflection coefficients for different interfaces in the subsoil: air/fresh water, air/seawater, air/NAPL (Non-Aqueous Phase Liquid), NAPL/water and water/NAPL. We consider a range of NAPL saturations, where the complementary fluid is water with 0.65 ppt (parts per thousand) of NaCl. The common feature is that the TM mode (parallel polarization) has a negative anomaly and the TE mode (perpendicular polarization) has a positive anomaly. For the cases studied in this work, pseudo Brewster´s angles appear beyond 40º for the air/NAPL and NAPL/water interfaces and at near offsets (below 40º) for the water/NAPL interface. Pseudo critical angles are present for the water/NAPL interface. Besides the reflection strength, the phase angle can be used to discrimminate between low and high conductivity NAPL, when the properties of the upper medium are known. A wavenumber-frequency domain method is used to compute the reflection coefficient and phase angle for synthetic radargrams. This method and the curves can be used to interpret the Amplitude Variations with offset (AVO) of reflection events in radargrams obtained with the GPR (Ground Penetrating Radar).