Hydrocarbon microseepage-related geobotanical analysis in and around oil fields

Abstract

Hydrocarbon microseepage can be detected by its altering effect on rocks, soils, and overlying vegetation. This study examines the impact of hydrocarbon seepage on vegetation. Microseeping hydrocarbons alter soil chemistry, often creating an environment that can impact the health of overlying vegetation; these effects can be observed using remote sensing. Blackburn and Eagle Springs oil fields in Nevada; Patrick Draw and Little Buffalo Basin oil fields in Wyoming; and Cement oil field in Oklahoma were selected for this study because previous investigations confirmed the presence of microseeping hydrocarbons in these locations. In this study, moderate resolution imaging spectroradiometer's (MODIS) monthly average normalized difference vegetation index (NDVI) data from January 2003 to December 2012 were used to observe vegetation health inside oil fields. Average NDVI was calculated for these locations. The typical range of NDVI in desert environments, such as those observed in semi-arid desert environments, can range from 0.18 to 0.49, depending on the season. In Blackburn Oil Field, the averaged NDVI near hydrocarbon production is 0.22, whereas it is 0.23 in areas where production does not occur. In Eagle Springs oil field, the average NDVI is 0.13, while it is 0.22 in surrounding areas. In Patrick Draw, the average NDVI is 0.14 in the oil field versus 0.15 in surrounding areas. In Little Buffalo Basin oil field, the NDVI is 0.19, and it is 0.23 in nearby areas where production does not take place. In Cement, Oklahoma, average NDVI is 0.47 in the oil field and 0.48 outside the oil field. Lower NDVI inside oil fields compared to surrounding areas may indicate lower abundance of vegetation or stressed vegetation, possibly as a result of hydrocarbon seepage and production.