The Evaluation of Hydrocarbon Potential Generation for Source Rocks by Near-Infrared Diffuse Reflection Spectra
ZHANG Yu-jia1,3,6, XU Xiao-xuan2,3, SONG Ning4, WU Zhong-chen5, ZHOU Xiang2, CHEN Jin2, CAO Xue-wei2, WANG Bin2,3*
1. The TEDA Applied Physics School, Nankai University, Tianjin 300457, China 2. School of Physics, Nankai University, Tianjin 300071, China 3. The Key Laboratory of Advanced Technique and Fabrication for Weak-Light Nonlinear Photonics Materials, Ministry of Education, Nankai University, Tianjin 300457, China 4. PetroChina Pipeline R&D Center, Langfang 065000, China 5. School of Space Science and Physics, Shandong University at Weihai, Weihai 264209, China 6. Shenyang Branch of China Coal Research Institute, Fushun 113122, China
Abstract：Near-infrared (NIR) and mid-infrared (MIR) diffuse reflection spectra were compared and evaluated for hydrocarbon potential generation of source rocks. Near-infrared diffuse reflectance often exhibits significant differences in the spectra due to the non-homogeneous distribution of the particles, so the signal-to-noise ratio of NIR is much lower than MIR. It is too difficult to get accurate results by NIR without using a strong spectral preprocessing method to remove systematic noise such as base-line variation and multiplicative scatter effects. In the present paper, orthogonal signal correction (OSC) and an improved algorithm of it, i.e. direct orthogonal signal correction (DOSC), are used as different methods to preprocess both the NIR and MIR spectra of the hydrocarbon source rocks. Another algorithm, wavelet multi-scale direct orthogonal signal correction (WMDOSC), which is a combination of discrete wavelet transform (DWT) and DOSC, is also used as a preprocessing method. Then, the calibration model of hydrocarbon source rocks before and after pretreatment was established by interval partial least square (iPLS). The experimental results show that WMDOSC is more successfully applied to preprocess the NIR spectra data of the hydrocarbon source rocks than other two algorithms, and NIR performed as good as MIR in the analysis of hydrocarbon potential generation of source rocks with WMDOSC-iPLS pretreatment calibration model.
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