Assessing the effect of hydrocarbon oil type and thickness on a remote sensing signal: A sensitivity study based on the optical properties of two different oil types and the HYMAP and Quickbird sensors
Assessing the effect of hydrocarbon oil type and thickness on a remote sensing signal: A sensitivity study based on the optical properties of two different oil types and the HYMAP and Quickbird sensors
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DOI：
10.1016/j.rse.2009.05.010
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发表时间：
2009-09
影响因子：
13.5
通讯作者：
M. Wettle;P. Daniel;G. Logan;M. Thankappan
中科院分区：
文献类型：
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作者：
M. Wettle;P. Daniel;G. Logan;M. Thankappan
我们测量了两种天然存在的澳大利亚碳氢化合物油的光吸收特性，一种是吉普斯兰轻质原油，一种是西北大陆架轻质凝析油。利用这些测量结果，结合估计的传感器环境噪声阈值，计算了高光谱HYMAP和多光谱Quickbird传感器对每种油类型的可探测性的理论最小极限（作为油厚度的函数）。在Quickbird绿色通道中，Gippsland原油在20微米或更厚的层厚处可被识别。HYMAP传感器理论上能够在大约6个传感器通道中检测厚度为10 μ m的Gippsland原油层。相比之下，西北陆架轻质凝析油在200µm以下的任何厚度下都无法被传感器检测到。因此，光学遥感不适用于检测与这种轻凝析油类型相关的诊断性吸收特征，这是澳大利亚西北陆架地区和世界各地凝析油中发现的许多碳氢化合物油的典型化学特征。因此，油品类型是影响光学遥感对天然浮油检测识别适用性的关键因素。我们建议，在将光学遥感器应用于石油勘探之前，应进行传感器和石油特定灵敏度的研究。使用两种不同的实验室方法，基于反射率的方法和基于透射率的方法获得了油的光学性质。基于反射率的方法实施起来相对复杂，但选择这种方法是为了尽可能接近地复制现实世界中对水中油膜的遥感测量条件。基于透射率的方法，基于标准的实验室分光光度测量被发现产生的结果与基于反射率的方法很好地一致。因此，对于未来针对石油和传感器的敏感性研究，我们建议采用相对容易获得的基于透光率的方法，本文对此进行了详细介绍。
We measured the light absorption properties of two naturally occurring Australian hydrocarbon oils, a Gippsland light crude oil and a North West Shelf light condensate. Using the results from these measurements in conjunction with estimated sensor environmental noise thresholds, the theoretical minimum limit of detectability of each oil type (as a function of oil thickness) was calculated for both the hyperspectral HYMAP and multispectral Quickbird sensors. The Gippsland crude oil is discernable at layer thickness of 20 µm or more in the Quickbird green channel. The HYMAP sensor was found to be theoretically capable of detecting a layer of Gippsland crude oil with a thickness of 10 µm in approximately six sensor channels. By contrast, the North West Shelf light condensate was not able to be detected by either sensor for any thickness up to 200 µm. Optical remote sensing is therefore not applicable for detecting diagnostic absorption features associated with this light condensate oil type, which is typical of the chemistry of many hydrocarbon oils found in the Australian Northwest Shelf area and condensates world wide. We conclude that oil type is critical to the applicability of optical remote sensing for natural oil slick detection and identification. We recommend that a sensor- and oil-specific sensitivity study should be conducted prior to applying optical remote sensors for oil exploration. The oil optical properties were obtained using two different laboratory methods, a reflectance-based approach and transmittance-based approach. The reflectance-based approach was relatively complex to implement, but was chosen in order to replicate as closely as possible real world remote sensing measurement conditions of an oil film on water. The transmittance-based approach, based upon standard laboratory spectrophotometric measurements was found to generate results in good agreement with the reflectance-based approach. Therefore, for future oil- and sensor-specific sensitivity studies, we recommend the relatively accessible transmittance-based approach, which is detailed in this paper.