Assessment of Soil Properties in Proximity to Abandoned Oil Wells

The oil and gas booms of the late 19th century left tens of thousands of wells in Wood County, Ohio abandoned and improperly capped. This allows hydrocarbons to seep into the surrounding soil. Detection of these wells proves difficult because many of the wells are buried and their locations lost. To be able to detect the oil wells over large areas, different remote sensing techniques can be used to detect changes in soil properties caused by the presence of hydrocarbons. However, the capability of this technology depends on spatial and spectral resolution of a sensor and in situ data are often necessary. In this study, in-situ hyperspectral reflectance data and thermal imaging are used in conjunction with clay mineral X-ray diffraction analysis to identify soil properties around abandoned wells located in an agricultural area in Wood County, Ohio. This study is confirmation of previous finding and it serves to indicate uncertainties related to a limited sampling effort, and to address the importance of field sampling strategies and adequate remote sensing techniques. Non-commercial satellite based remote sensors of medium, spatial resolution, such as Landsat, are inadequate for detection of the small abandoned wells in Wood County, Ohio. In situ hyperspectral reflectance measurements, used to simulate WorldView-3 spectral and spatial resolution, suggest that this high spatial resolution commercial satellite is optimal for detecting small abandoned oil wells. It is confirmed that a spectral band ratio in the spectral range between 2.185-2.225 µm and 2.295-2.365 µm (WorldView-3 shortwave bands 6 and 8, respectively) is effective. The clay mineral X-ray diffraction analysis suggests that these changes in the spectral information occur predominately due to the hydrocarbons; clay mineral content changes in the soil did not affect the soil spectral iii signature to a greater extent. Thermal imaging identified higher surface temperatures in soil with higher hydrocarbon content when compared to a control site. Based on direct hydrocarbon testing results, only long chain hydrocarbons (C30+) are present in the soil, suggesting that the wells are not active and that hydrocarbons are not presently leaking from the well. Rather, the soil contamination originated in the past, most likely during drilling of the wells decades ago. The limited results in this study are suggestive for further research. More field data, including crop information are needed to support the effectiveness of remote sensing technology in similar studies. It is suggested that using high spectral resolution commercial satellites (e.g. WorldView3) in conjunction with thermal imaging can be an optimal approach to identify the soil contamination in proximity to abandoned wells in Wood County, Ohio.

Author: Matthew James Magdic

Spectral Evolution is a leading manufacturer of field-portable UV-Vis-NIR remote sensing spectroradiometers and spectrometers for applications including geological remote sensing, ground-truthing, spectral remote sensing, environmental and climate research, crop and soil research, vegetative studies, forestry and canopy studies, radiometric calibration transfer, upwelling and downwelling measurement and more. Our UV-Vis-NIR spectrometers and spectroradiometers provide the best combination of high resolution and high sensitivity resulting in the most precise field portable instruments available on the market.

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