岩心光谱扫描仪数据处理应用研究

钻探是地质勘探的重要手段之一，近年来，随着我国地质事业的发展，大量岩心的存放和共享成了亟待解决的问题，研制岩心光谱扫描仪，实现岩心数字化解决了这一问题。然而，岩心光谱数据和图像数据的大量产生，对数据处理又提出了新要求。根据光谱学原理和光谱分析方法，对岩心扫描仪的光谱数据进行光谱分析和蚀变矿物填图，可以为地质科研、矿床分析和外围找矿提供依据。岩心图像也是岩心信息不可缺少的部分，由于岩心扫描仪探测器的局限性、光照条件以及岩心圆柱形的影响，会造成采集到的岩心图像光照不均和辐射畸变。使用非线性的双边滤波法来锐化图像，然后用黑白板定标的方法校正岩心图像，使岩心图像更加接近真实状况。用角点检测法进行特征点检测，完成了图像自动拼接工作，把一张张岩心图像按照岩心钻孔的顺序拼接成岩心柱和岩心盘，使岩心图像显示更直观。矿物的光谱分析是岩心扫描技术的核心，矿物不同，其特征吸收峰的位置也不同。常采用的矿物检索方法是吸收峰位匹配法，该方法适合混合矿物光谱检索。峰位匹配的依据是标准数据库，提出了分类数据库检索法，即根据矿物类型的不同，把标准数据库分为泥化蚀变矿物库、斑岩型蚀变矿物库、绢云母化蚀变矿物库等子数据库，根据样品图像及所处地质环境判断，选择合适的子数据库进行检索分析。文中进行两个实验，分别使用标准数据库和分类数据库分析同一样品，其分析结果表明准确率后者更高；使用标准数据库和分类数据库对同一批样品（141个样品）进行处理，用时分别是231和44 s。实验证明：分类数据库法不仅可以提高检索的准确度，还能大大加快检索速度，是准确、快速检索海量数据的有效方法。该方法是光谱检索中新颖、独特、有效的方法，是本文的创新之处。矿物光谱含有丰富的信息，其特征峰的峰强度、峰强比、峰位移、半高宽和反射率分别反应矿物的相对含量、相对温度、阳离子交换情况、结晶度和颜色等信息，提取同一批矿物的这些信息，对比分析，可获得成矿模型，揭示成矿规律。以安徽宣城一个钻孔为例，对岩心光谱扫描仪的数据进行自动图像拼接、光谱分析和蚀变矿物填图。从蚀变矿物信息提取图分析看出，该地区是酸性、低温的地质环境，低温区岩石颜色较深，在低温区中间也有高岭石、蒙脱石，说明具有良好的储油环境。经实践证明，该方法不仅效率高，能节省大量人工工作量，还能得到高质量的岩心盘拼接图、岩心柱状拼接和蚀变矿物信息提取图，是地质工作者处理岩心数据实用、可靠的方法。

Research on Data Processing of Core Spectral Scanner

Drilling is one of the important means of geological exploration. In recent years, with the development of China’s geology, the storage and sharing of a large number of cores has become an urgent problem to be solved. The problem has been solved through research and development of a core spectral scanner to realize the digitalization of cores. However, the massive production of core spectral data and image data puts forward new requirements for data processing. According to the principles of spectroscopy and spectral analysis methods, spectrum analysis and altered mineral mapping of the spectral data of the core scanner can provide the basis for geological scientific research, deposit analysis, and prospecting. This paper proposes a classification database retrieval method, which not only improves the accuracy of retrieval, but also greatly accelerates the retrieval speed. The core image is also an indispensable part of the core information. Because of the limitation of the core scanner detector, the illumination conditions, and the influence of the cylindrical core, the collected core image will have uneven illumination and radiation distortion. Utilizing the nonlinear bilateral filtering method to sharpen the image, and applying the black and white plate calibration method to correct the core image make the core images closer to the real condition. The automatic image mosaic is completed by detecting feature points using the corner detection method. Core images are spliced into core columns and core trays one by one according to the drilling sequence, making the core images display more direct-viewing. Spectral analysis of minerals is the key to core scanning technology. Different minerals have different peak positions of characteristic absorption. Normally utilize the peak absorption matching method to search minerals, which is suitable for mixed mineral spectral retrieval. The matching of peak positions is based on a standard database. This paper proposes a classification database search method: based on the types of minerals, the standard database is divided into sub-databases of argillization alteration database, porphyritic alteration database, sericite alteration database and so on. According to the images of the samples and the geological environment in which they are located, select the appropriate subdatabase for search analysis. Two experiments were conducted in this paper. The same batch of samples were analyzed using the standard database and the classification database respectively. The results showed that the accuracy of the latter was higher; 141 samples were processed taking 233 seconds and 44 seconds with each method. Experiments prove that the classification database method is an effective method for retrieving large amounts of data accurately and quickly, which can both improve the accuracy of the retrieval, and greatly speed up the retrieval. This method is a novel, unique, and effective means in spectral retrieval. Solving efficiency problems for batch mineral data retrieval is the innovation of this paper. Mineral spectrums contain rich information, whose peak intensity, peak-to-peak- ratio, peak shift, FWHM, and reflectance are related to the relative content of minerals, temperature, cation exchange, crystallinity and color respectively. The metallogenic model can be obtained by comparing and analyzing the information from the same batch of minerals, which reveals the regularity of mineralization as well. This paper takes a drilling in Xuancheng, Anhui Province as an example to process automatically image stitching, spectral analysis and altered mineral mapping of the core spectral data. According to the analysis of information extracted from altered minerals, the area is an acidic, low-temperature geological environment, with darker rocks in the low-temperature areas and kaolinite and montmorillonite in the middle of the low-temperature areas, indicating a good oil storage environment. The experimental results show that this method can not only save a lot of manual workload, but also obtain high-quality core tray and columnar core splices and altered mineral information extraction graphs, which is a practical and reliable method for geological workers to process core data.