Abstract Estuarine tidal bar sandstones are complex reservoir geobodies commonly exploited by the oil and gas industry. In order to better predict the reservoir potential of these geobodies, this study provides a modern-day reservoir analogue, describing tidal bars in the inner and outer Gironde estuary from the microscopic to the macroscopic scale. The originality of this work lies in the multi-scale study of modern estuarine tidal bars based on numerous piston cores extracted in a high-energy environment. This work demonstrates that these tidal bars are composite sedimentary bodies made up of individual reservoir sand units separated by thick muddy layers. Their vertical facies associations and internal architectures are controlled by local hydrodynamic variations and seasonal river influxes. Detrital clay grain coats are notably characterized using a portable and handheld mineral spectrometer from the base to the top of the tidal bars. X-ray diffraction and electron microscopes reveal that these coats are mainly composed of di-octahedral smectite, illite, chlorite and kaolinite associated with other components such as diatoms or pyrite. The best reservoir geobodies are those with the minimum clay permeability barriers at the macro and mesoscale. An optimum coated grain content and clay fraction volume is also needed for generating authigenic clay coatings and inhibiting quartz overgrowth. These conditions are met within the tidal sand bars of the outer estuary funnel that are expected to be the best reservoir geobodies in deeply buried sandstones.

中文翻译：

---

吉伦特河口潮汐坝的相组合、碎屑粘土颗粒层和矿物学特征。深埋河口砂岩储层的现代类似物

摘要 河口潮滩砂岩是油气工业常用的复杂储层地质体。为了更好地预测这些地质体的储层潜力，本研究提供了现代储层类比，从微观到宏观尺度描述了吉伦特河口内外的潮汐坝。这项工作的独创性在于基于在高能环境中提取的众多活塞芯，对现代河口潮汐棒进行了多尺度研究。这项工作表明，这些潮汐坝是由被厚泥层隔开的单个储层砂体单元组成的复合沉积体。它们的垂直相关联和内部结构受局部水动力变化和季节性河流流入控制。碎屑粘土颗粒涂层的显着特征是从潮汐棒的底部到顶部使用便携式和手持式矿物光谱仪。X 射线衍射和电子显微镜显示，这些涂层主要由双八面体蒙脱石、伊利石、绿泥石和高岭石组成，并伴有其他成分，如硅藻或黄铁矿。最好的储层地质体是那些在宏观和中尺度上具有最小粘土渗透障碍的地质体。生成自生粘土涂层和抑制石英过度生长也需要最佳的涂层颗粒含量和粘土部分体积。这些条件在外河口漏斗的潮汐沙坝内得到满足，这些沙坝有望成为深埋砂岩中最好的储层地质体。