加拿大魁北克省奥陶系Utica页岩岩石物理特性

Petrophysical properties characterization of Ordovician Utica shale in Quebec, Canada

利用x射线衍射（XRD）矿物分析、x射线能量色散光谱分析（EDS）、扫描电镜（SEM）、聚焦离子束扫描电镜（FIB-SEM）等手段，对加拿大魁北克省奥陶系Utica页岩矿物成分、孔隙度、微观孔隙结构、表面润湿性等岩石物理特性进行了研究。压汞仪测试结果显示测试样品的孔隙直径在15-200nm；XRD矿物分析和EDS元素测试显示Utica页岩中的非黏土矿物以方解石和石英为主，黏土矿物以伊利石和绿泥石为主；利用SEM对岩心表面孔喉进行了观测，图像显示Utica页岩中发育多种类型的孔隙，比如粒内孔、粒间孔、有机质孔等，其中，有机物（干酪根）中的孔隙在纳米级别（10～50nm）；利用FIB—SEM完成了250张扫描电镜图像，利用这些图像重建了三维层析成像模型和孔隙分布几何模型。润湿性测试结果显示，Utica岩心样品呈弱水湿一中性润湿，水力压裂过程中大部分添加剂可以将页岩表面改变成更倾向于水相润湿的状态。

With multiple techniques, the following measurements and analysis were made to characterize the Ordovician Utica shale samples： mineralogy, porosity, microstructure, and surface wettability etc. The test of mercury injection apparatus showed that the pore size of Utica shale is 15-200 nm. X-ray diffraction （XRD） mineralogy analysis and Energy-Dispersive X-ray Spectroscopy （EDS） indicated that in Utica shale non-clay minerals are dominated by calcite and quartz, while clay minerals by illite and chlorite. With the images from scanning electron microscope （SEM）, the surface microstructure examination showed various types of pores exist in Utica shale, such as intragranular, intergranular, organic etc. And the pores in organic matter （kerogen） were found in nanometer size （10 to 50 nm）. A three-dimensional tomography model and a geometry model of the pores space using FIB-SEM imaging tomography were reconstructed with 250 SEM images. It provides visual insights into the petrophysical properties of Utica shale. Finally, the wettability tests displayed that Utica shale has weak-water wet to intermediate wettability.