Hydrocarbon Microseepage Detection Using Image Analysis Approach for North East Region India

Abstract

The vertical movement of hydrocarbons such as oil and gas that traverse through fractures and faults zones in rocks and weak planes between geological layers from the Earth’s subsurface to the surface form seepage at the surface, known as microseepage. Hydrocarbon microseepage is a key indicator to detect potential oil and gas reservoirs regions. Hydrocarbon microseepage leads to alterations in geobotanic characteristics and mineral composition resulting change in the concentration of ferrous iron, clay, and carbonate minerals. These mineral alterations are indicative of potential hydrocarbon microseepage locations, suggesting the presence of underlying oil and gas reservoirs. The altered regions exhibit distinctive reflectance spectral characteristics that can be identified through remote sensing imagery. This study is focused on detecting the hydrocarbon microseepage using image analysis in North Eastern regions of India. Sentinel-2 imagery was used to identify surface features associated with microseepage. A fuzzy set-based approach was employed to integrate the outcomes of band indices to determine geobotanic anomalies and mineral alteration.  Each selected band indices were treated as fuzzy sets, with defined membership functions. The membership degree of each pixel, reflecting the likelihood of specific altered minerals, was then calculated. The study demonstrates that areas with healthy vegetation exhibit higher pixel values, while regions experiencing stress due to microseepage display lower pixel values. By comparing the hydrocarbon exploration map (Source - VEDAS GIS ISRO) with the vegetation stress map, it was found that the several places in study area with high stress values, falls under the hydrocarbon prospect area. This analysis allows for the identification and mapping of potential petroleum prospect regions and zones where vegetation is under stress. By observing the variations in pixel values, we can effectively delineate areas with healthy vegetation and those affected by the impact of hydrocarbon microseepage, providing valuable insights into the characterisation of petroleum prospects and stressed vegetation zones within the study area. The analysis can be further improved by incorporating high resolution images followed by ground truthing.