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Hydrocarbon Microseepage and Geobotanical Anomalies

Abstract

Recently, unconventional methods for oil prospecting are becoming popular due to the rising cost of traditional means. This study is focused on the effect of hydrocarbon microseepage on vegetation. Microseeping hydrocarbons alter soil chemistry oftentimes creating an anaerobic environment which has an impact on the health of overlying vegetation. These effects can be observed using remote sensing. Blackburn and Eagle Springs oilfields in Nevada and Patrick Draw oilfield in Wyoming were selected for a preliminary study, because they are dominated by sagebrush shrub land: an ecosystem which contains species of vegetation which are not tolerant of anaerobic conditions. Previous studies and field observations found that sagebrushes (Artemisia tridentata) are stunted and provide sparse land cover inside Patrick Draw oilfield. Outside of the field, vegetation was observed to be denser and have greater height. In this study, Moderate Resolution Imaging Spectroradiometer's monthly average Normalized Difference Vegetation Index (NDVI) data from January 2003 to December 2012 were used to observe vegetation health inside these oilfields. Average NDVI was calculated for these locations. In Patrick Draw, NDVI was found to be lower during the months of June and July than published values for this type of ecosystem. A more detailed study will be focused on Cement oilfield in Oklahoma, where field work will be conducted using a Specim ground-based hyperspectral camera system with a visible near infrared and short wave infrared sensors. Vegetation near rock alteration sites will be scanned. Samples of Post oak (Quercus stellata) and blackjack oak (Quercus marlilandica): dominant vegetation in this region which has low tolerance of anaerobic conditions will be collected for spectral analysis using an ASD Fieldspec spectroradiometer. A RIEGL VZ-400 Terrestrial Laser Scanner will be used to acquire three dimensional data in this region. Samples and data will be collected in three locations: one inside the field, one just outside of the field, and one about 100 km away from the field. Anomalies in the distribution of vegetation will be correlated to areas known to have microseepage.