Detecção de exsudações de óleo no complexo de cantarell (golfo do méxico) com dados sar polarimétricos do satélite radarsat-2

Abstract

The occurence of oil seeps on the sea surface resulting from exudation of active oil systems, commonly referred as seepage slicks, has been extensively recorded by SAR (Synthetic Aperture Radar) imaging systems.RADARSAT-2 is a Canadian satellite that obtains useful information to reconnaissance/description of this kind of features. Polarimetry is consolidating in the oil industry as a sophisticated technique to study marine seeps. The Cantarell Complex is currently the most prolific natural exudation site of the globe. This project aimed to contribute to the discussion about the physical properties of exudation from RADARSAT-2 complete polarimetric data (quad-pol). In addiction, the fact that the research counts on two images acquired at the same place and both on Fine Quad operational mode, but having some time interval between acquisitions and different incidence angles ( 19,0°-22,7° and 33,7°-36,7°), made it possible to evaluate the geometry imaging influence on the signature of targets. For this purpose, the Cloude & Pottier (1997) diagram as applied, wich defines nine distinct zones to analyze scattering mechanisms. Therefore, samples of four targets (sea, platform, oil and false target) were generated- size 3x3 pixels- and, individually, extracted the data to relate in graphs and diagram entropy(H) vs. alpha angle. The results showed (i) the sea is a Bragg-type surface independent of the incidence angle,(ii) the platforms have double-bounce scattering, but low angles are inadequate for their characterization, (iii) false targets (associated low wind zones) are moderately random/almost-deterministic surfaces, and(iv) the oil behaves either as Bragg (19,0°-22,7°), or as random/anisotropic surface (33,7°-36,7°).