Delineating Pixels of Natural HydrocarbonMicro-Seepage Induced Alterations and Anomaliesin Overlying Soils and Sediments in Ugwueme,with ASTER Data and Band Ratio Technique

Abstract

The earth’s underlying hydrocarbon-bearing reservoirs frequently leak. These reservoirs leak because of their inadequate sealing, and at high pressure, oil and gas escape vertically or nearly vertically to the earth’s surface as seepage. Micro-seepages on the earth’s surface cause oxidationreduction reactions, which cause anomalies in the soils and sediments beneath them. Remote sensing (RS) and geographic information systems (GIS) are important tools for investigating hydrocarbon micro-seepage-induced changes and anomalies in overlying soil and sediments. In this study, ASTER remote sensing data was adopted to delineate pixels of hydrocarbon micro-seepage-induced anomalies in Ugwueme, south-eastern Nigeria. Band Ratio (BR) was used as a spectral enhancement technique to detect alterations and anomalies in the overlying soil and sediments. ASTER BR of 2/1 improves ferric iron; (5+7)/6 improves clay minerals; (1+4)/(2+3) improves ferrous iron; and 4/(6+9) improves gypsum. The study highlights that BR is an excellent spectral enhancement technique for delineating areas of alterations and anomalies induced by hydrocarbon micro-seepage.