Terahertz Spectral Characteristics of Rocks With Different Lithologies
MIAO Xin-yang1,2,3, LIU Xue-cong1,3, CHEN Meng-xi3, CHEN Si-tong3, ZHANG Shan-zhe1, LU Wan-ting3, PENG Xue3, ZHAN Hong-lei2,3, ZHU Ming-da1, ZHAO Kun1,2,3*
1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
2. College of New Energy and Materials, China University of Petroleum, Beijing 102249, China
3. Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection, Petroleum and Chemical Industry Federation, China University of Petroleum, Beijing 102249, China
Abstract：Determining the types of rock is crucial to understand the origin and history of geological units. The recognition and classification of lithologies are usually performed by experienced researchers based on the colors and morphologies with the accuracy not guaranteed, particularly when trying to distinguish between units with similar lithology. Different from the subjective judgment, spectral means can provide multiple optical parameters among different frequencies. Information of the samples can be determined by establishing the relationship between optical parameters and the physical properties, to achieve qualitative and quantitative evaluation. In this study, terahertz (THz) spectroscopy was employed to discriminate the lithology of rock gathered from different regions. Based on the relations between effective refractive index (n) and attenuation coefficient (a), the samples can be classified into four gatherings, with the result in agreement with their lithologies. Besides, the variation tendency of THz parameters was plotted with the componential and structural properties, indicating that the variant THz responses were resulted by varying compositions and structures for different classifications of rocks. The mineral composition is the main factor affecting the absorption and refraction of the THz wave. Element content can be estimated with the THz parameters for Fe and Mg. For sandstone with stable elements, both the absorption and refraction of THz wave are negatively correlated with the porosity. Organic content in oil shale has a reverse effect on THz absorption and refraction, in which the higher oil yield results in a stronger absorption and lower refraction. Herein, the refractive index is positively correlated with the absorption for granite, limestone and sandstone, while the relation between them is negatively correlated for oil shale. Our results prove that the THz technique is a promising means for determining the lithology and petrophysics properties, which will be a significant supplementary in geology research.
基金资助: supported by the National Nature Science Foundation of China (11804392), the Beijing Natural Science Foundation (1184016), and the Science Foundation of China University of Petroleum, Beijing (ZX20190163, 2462017YJRC029, 2462018BJC005, yjs-2017019)
通讯作者:
赵 昆
E-mail: zhk@cup.edu.cn
作者简介: MIAO Xin-yang，(1992—)，received the Ph. D. degree from China University of Petroleum, Beijing
e-mail:
miaoxy@cup.edu.cn
引用本文:
苗昕扬，刘学聪，陈梦溪，陈思同，张善哲，路婉婷，彭 雪，詹洪磊，朱明达，赵 昆. 不同种类岩石的太赫兹光谱特征研究[J]. 光谱学与光谱分析, 2021, 41(04): 1314-1319.
MIAO Xin-yang, LIU Xue-cong, CHEN Meng-xi, CHEN Si-tong, ZHANG Shan-zhe, LU Wan-ting, PENG Xue, ZHAN Hong-lei, ZHU Ming-da, ZHAO Kun. Terahertz Spectral Characteristics of Rocks With Different Lithologies. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(04): 1314-1319.
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