Remote detection of a tonal anomaly in an area of hydrocarbon microseepage, Tucano basin, north-eastern Brazil

Abstract

Abstract. Mapping of a tonal anomaly in an area of hydrocarbon microseepage was possible using a Landsat-Thematic Mapper false-colour composite consisting of TM2/3, TM4/3 and of the di erence TM2/3-TM4/3, displayed as red, green and blue, respectively. In this false-colour composite, green and yellow express variations in the vegetation cover, whereas hues of magenta are related to terrain conditions representing bleached materials, which occur close to the centre of a soil gas anomaly. Simultaneous occurrence of anomalous soil gas values with magnetic and radioactive minerals suggests that a reducing environment associated with the microseepage phenomenon created the bleached materials, identi® ed as a tonal anomaly in the enhanced TM image.

Detecting and Measuring Gas Seepage

“…Detection of bubbles and gas-charged sediments through high acoustic backscatter using side-scan sonar or multibeam echosounders (e.g., Orange et al, 2002;Rollet et al, 2006;Judd and Hovland , 2007;and references therein) Changes in vegetation patterns due to hydrocarbons in soil (e.g., Almeida-Filho et al, 1999;Noomen et al, 2012;Lammoglia and de Souza Filho, 2013) Fig. 4.5 Main indirect methods of natural gas seepage detection the one described in Chap.…”

“…Hydrocarbons in the soil may impact vegetation growth and health, and can be detected through the analysis of reflectance spectra (Almeida-Filho et al 1999;Noomen et al 2012;Lammoglia and de Souza Filho 2013). The reflectance of healthy vegetation can be observed using visible light based on the absorption features caused by plant pigments such as chlorophyll and carotenoids, and in the near infrared (NIR) and shortwave infrared (SWIR) using adsorption bands related to internal leaf structure, water content, and leaf area.…”

Multispectral remote sensing mapping for hydrocarbon seepage-induced lithologic anomalies in the Kuqa foreland basin, south Tian Shan

“…Spectral enhancement of remote sensing imagery, by means of principal component analysis (PCA) and band ratios has been successfully used in several studies to enhance surface anomalies and alternation. For example, Almeida et al (1999Almeida et al ( , 2002 mapped clay and ferric iron minerals associated with hydrocarbon seepage in the Serra do Tona Plateau through the application of PCA and band ratios.…”

Visible and Infrared Remote Imaging of Hazardous Waste: A Review

“…Figure 5 documents the changes in extent of a land fill fusing spaceborne multispectral images over time, and Figure 6 demonstrates the use of multispectral data for hazardous waste site identification. Landsat TM data have been utilized to detect altered surface area due to hydrocarbon microseepages by Almieda-Filho et al [37]. Utilizing band ratios (TM2/3, TM4/3) and a difference image, features related to a reducing environment that created bleached materials were identified.…”