Multiscale characterization of three-dimensional pore structures in a shale gas reservoir: A case study of the Longmaxi shale in Sichuan basin, China
Multiscale characterization of three-dimensional pore structures in a shale gas reservoir: A case study of the Longmaxi shale in Sichuan basin, China
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页岩气藏三维孔隙结构多尺度表征——以四川盆地龙马溪组页岩为例
DOI：
10.1016/j.jngse.2019.04.009
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发表时间：
2019
影响因子：
--
通讯作者：
Jin Chan
中科院分区：
文献类型：
--
作者：
Wang Yu;Wang Lihua;Wang Jianqiang;Jiang Zheng;Wang Chun-Chieh;Fu Yanan;Song Yen-Fang;Wang Yanfei;Liu Dezheng;Jin Chan
采用X射线CT和聚焦离子束扫描电镜成像技术，对四川盆地龙马溪页岩样品进行了多尺度成像研究，成像像素从3.25 μm到10 nm。孔隙、有机质（OM）和黄铁矿在多尺度下进行了分割和重构，并根据体积分数误差条的收敛性确定了不同尺度下各相的代表性单元体积（REV）。结果表明，在不同的阶段，在每个尺度上的REV变化。REV的确定既确定了不同方法的适用尺度，也确定了具体结构的适宜尺度。不同尺度下测定的LMX泥页岩孔隙度有两个数量级的显著差异。这种差异可能是由结构异质性和方法的局限性造成的。这项研究证实，REV是一种可行的和强大的方法在泥页岩建模使用多尺度三维成像。将多尺度三维成像技术应用于全球页岩气储层，可以对低渗透系统内的迁移机制评估有重要的见解。
A typical Longmaxi (LMX) shale sample from Sichuan basin, China, is investigated in three dimensional through multiscale tomography methods spanning pixel sizes from 3.25 μm to 10 nm, combining X-ray computed tomography and focused ion beam-scanning electron microscopy imaging techniques. Pores, organic matter (OM) and pyrite were segmented and reconstructed at multiple scales and the representative elementary volume (REV) of each phase at different scales based on the convergence of error bars in the volume fraction are determined. Results show that REVs at each scale varied between different phases. The determination of REV defined the applicable scale of different methods as well as the appropriate scales of specific structures. Porosity of LMX shale determined at different scales shows significant difference at two orders of magnitude. This difference likely was caused by structural heterogeneity together with the limitations of methods. This study confirms that REV is a feasible and powerful approach in modeling shale using multiscale 3D imaging. The application of multiscale 3D imaging techniques to worldwide shale gas reservoirs could allow for significant insights into the assessment of migration mechanisms within low-permeability systems.