Quartz types and origins in the paleozoic Wufeng-Longmaxi Formations, Eastern Sichuan Basin, China: Implications for porosity preservation in shale reservoirs

摘要

Quartz in shales has been demonstrated to exert a significant effect on shale gas production by influencing rock mechanical behavior and reservoir porosity; however, quartz types and origins in shales are complicated and challenging to study due to their fine-grained nature. In this study, we propose combining thin section images, scanning electron microscopy (SEM) images, energy dispersive spectroscopy (EDS) maps, cathodoluminescence (CL) images and geochemical data to investigate quartz types and origins in shale formations. Shale samples from the Ordovician Wufeng-Silurian Longmaxi Formations, Eastern Sichuan Basin, China were used to study quartz types, origins and the effect of quartz cementation on porosity development.