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Detection of hydrocarbon bearing sand through remote sensing techniques in the western slope zone of Songliao basin, China

To detect oil‐bearing sand in the western slope zone of Songliao Basin, China, a Landsat‐7 Enhanced Thematic Mapper Plus (ETM+) image was used to identify anomalous areas caused by hydrocarbon leakage. Enhancement of the image involved three techniques including Principal Component Analysis (PCA), band ratioing and False Colour Composition (FCC). In this paper, experimental work gives a detailed PCA description of different band combinations. The best four principal components (PCs)—1345‐PC3 (the third PC image of the PCA on band 1, 3, 4, 5), 1357‐PC3, 2357‐PC3 and 3457‐ PC4—were selected for FCC combined with band ratio layers. Based on the tonal characteristics of the existing bores and the basin boundary, differentiation of target areas in the four FCC images was achieved. Results indicated that anomalies are expressed as a halo in fuscous tone and located in the basin margin with an area of 70∼100 km2. Examination of the Ce/La ratio showed that the tonal anomalies are evidently associated with a reducing environment.