苏北盆地高邮凹陷花页1井古近系阜宁组裂缝脉体流体演化及其对页岩油充注过程的指示意义

Fluid evolution of fracture veins of Paleogene Funing Formation in well HY1 in Subei Basin and implications for shale oil filling

李超 罗涛 黄亚浩 刘义承 陈俊林 王川

LI Chao LUO Tao HUANG Yahao LIU Yicheng CHEN Junlin WANG Chuan

1. 中国石化 华东石油工程有限公司, 南京 211400; 2. 长江大学 资源与环境学院, 武汉 430100; 3. 中国地质大学(武汉) 资源学院, 武汉 430074

1. SINOPEC East China Petroleum Engineering Co., Ltd., Nanjing, Jiangsu 211400, China; 2. College of Resources and Environment, Yangtze University, Wuhan, Hubei 430100, China; 3. School of Earth Resources, China University of Geosciences(Wuhan), Wuhan, Hubei 430074, China

苏北盆地页岩油勘探开发取得重大突破。高邮凹陷花页1井岩心观察发现，古近系阜宁组二段富有机质页岩中天然裂缝发育，脉体内保存了大量页岩油气流体活动迁移的信息。以阜二段页岩裂缝充填的方解石脉体为研究对象，综合运用矿物学、元素地球化学、地质年代学以及地质流体技术，聚焦页岩裂缝脉体的古流体来源、脉体形成时间以及流体包裹体特征开展深入研究，提出页岩含油层埋藏、抬升剥蚀过程中古温度条件与对应地质时间。阜二段页岩裂缝主要产状类型为层理缝、滑脱缝、剪切缝、收缩缝和张性缝，裂缝内主要充填一期纤维状方解石脉体，方解石脉体表现为偏还原环境热液流体的来源；始新世中期阜二段裂缝脉体捕获原生绿色荧光油包裹体、始新世晚期捕获次生蓝色荧光油包裹体和第四纪晚期捕获次生绿色荧光油包裹体，分别指示了富有机质页岩主要存在三期页岩油的充注过程。页岩油的充注主要在页岩最大埋深时期形成，三垛构造运动对于该地区页岩油的调整运移具有重要作用。

A significant breakthrough has been made in the exploration and development of shale oil in the Subei Basin. Cores from well HY1 in the Gaoyou Sag of Subei Basin indicate the presence of well-developed natural fractures within the organic-rich shale of the second member of Paleogene Funing Formation. These fractures contain compelling evidence of shale oil, gas, and fluid activities and migration. This study specifically examines the calcite veins filling the shale fractures within the second member of Funing Formation. Through the integration of methodologies from mineralogy, elemental geochemistry, geochronology, and geological fluid analysis, the originof paleo fluids, the timing of vein formation, and fluid inclusions within the shale fracture veins are investigated. This study also sheds light on paleotemperature conditions and corresponding geological timeframes during the burial, uplift, and denudation of the shale oil-bearing layers. The primary fracture types observed in the second member of Funing Formation include bedding fractures, detachment fractures, shear fractures, shrinkage fractures, and tensile fractures, predominantly filled with fibrous calcite veins indicating a source linked to hydrothermal fluids in a reducing environment. Notably, three distinct stages of shale oil injection are evident within the organic-rich shale fracture veins of the second member of Funing Formation, marked by primary green fluorescent oil inclusions from the Middle Eocene, secondary blue fluorescent oil inclusions from the Late Eocene, and secondary green fluorescent oil inclusions from the Late Quaternary period. The primary accumulation of shale oil occurred during the period of maximum burial depth, emphasizing the significant role of tectonic movements, especially the Sanduo tectonic event, in the redistribution and migration of shale oil in the region.

国家自然科学联合基金“盆地深部地质作用过程与资源效应”(U20B6001)资助。

https://doi.org/10.11781/sysydz202402228