松科二井深层沙河子组泥岩三维显微CT成像及对深部油气预测的启示

为深化认识松科二井深层页岩气垂向变化规律，选取沙河子组3500~5700 m层段开展了X射线三维计算机断层扫描（X-ray 3D Computed Tomography，简称CT）成像实验。对19块直径2 cm的柱状岩心进行X射线CT扫描，获取了无损岩心扫描数据，并将其转化为灰度值信息。灰度值信息反映了样品中不同的组分，灰度高值代表骨架和矿物，灰度低值代表孔隙和裂缝。在此基础上，建立分辨率高达15 μm的岩心三维图像空间结构，对重建岩心孔隙模型的孔隙形态、空间展布和配位数进行了对比，对样品孔隙度和连通性在垂向上的分布规律进行了统计分析。结果表明，等效孔隙直径大的区域孔隙度高，配位数大的区域连通性好，孔隙度和连通性的垂向分布规律与传统认识相符，与测录井信息可以相互印证。实验证明，基于三维CT成像的数字岩心技术具有数据分辨率高、信息丰富的优势，可作为今后深部油气预测与评价的重要辅助手段。

3D microscopic CT imaging and significance of SK-2 deep mudstone of Shahezi Group

In order to deepen the understanding of the vertical change rule of the deep shale gas in the Songke 2 Well, the authors selected the 3500~5700 m section of the Shahezi Formation to carry out the X-ray 3D Computed Tomography (CT) imaging experiment.X-ray CT scan was performed on 19 pieces of 2 cm-diameter columnar cores to obtain non-destructive core scan data, and a three-dimensional image spatial structure with a core resolution of up to 15 μm was established.The pore morphology structure and space of the reconstructed core pore model were analyzed by comparative study of spatial distribution and coordination number, statistics of the vertical distribution of sample porosity and connectivity.This experiment proves that the digital core data have high resolution and rich information.The gray value information reflects different components in the sample.The skeleton and minerals are high gray values, and the pores and cracks are low gray values.Studies have shown that areas with large equivalent pore diameters have high porosity, and areas with large coordination numbers have good connectivity.The vertical distribution of porosity and connectivity is consistent with traditional knowledge and can be verified with logging information.It is believed that the digital core can be used as an important auxiliary method for deep core research in the future.