鄂尔多斯盆地延长组长7湖相页岩油地质特征评价  

Assessment of geological characteristics of lacustrine shale oil reservoir in Chang7 Member of Yanchang Formation, Ordos Basin

作　　者：张文正[1,2,3] 杨华[2,4] 杨伟伟[1,2] 吴凯[1,2] 刘飞[1,2] 

机构地区：[1]中国石油天然气股份有限公司长庆油田分公司勘探开发研究院,陕西西安710021 [2]低渗透油气田勘探开发国家工程实验室,陕西西安710018 [3]中国科学院广州地球化学研究所,广东广州510640 [4]中国石油天然气股份有限公司长庆油田分公司,陕西西安710021

出　　处：《地球化学》2015年第5期505-515,共11页Geochimica

基　　金：国家自然科学基金(41473046);国家重点基础研究发展计划项目(2014CB239003);长庆油田分公司科研项目(2014-6-5)

摘　　要：页岩油是重要的非常规油气资源之一。利用地球化学、测井、X射线衍射、扫描电镜等资料对鄂尔多斯盆地延长组长7页岩油的地质特征展开了研究。研究结果表明,鄂尔多斯盆地延长组长7湖相页岩层十分发育,根据岩性组合、地球化学等特征可以将长7页岩划分为"砂岩-页岩互层"、"厚层状Ⅰ类页岩"与"厚层状Ⅱ类页岩"等三种类型。长7湖相页岩层分布范围广且厚度较大,提供了页岩油成藏的基本地质条件;岩石中脆性矿物含量高,为页岩油勘探开发的必要条件;有机质丰度高、有机质类型好且有机质热演化程度适中,奠定了页岩油聚集成藏的物质基础;虽然长7页岩十分致密,但在扫描电镜下可见微米级裂隙,并且湖盆中部等地区发育物性相对较好的薄砂岩夹层,提供了页岩油的储集空间。分析测试资料显示,长7页岩含油性较好,并具有一定的含气量;薄砂岩夹层油源充足,紫外光下具有较强的荧光显示。综合地质条件及含油气性研究,"砂岩-页岩互层"分布区被评价为最有利的页岩油勘探目标区,"Ⅰ类页岩"较"Ⅱ类页岩"生烃条件更好,脆性更强,微米级裂缝更为发育,含油气性较好,为第二类有利勘探目标区。Shale oil is one of the important abnormal hydrocarbon resources. The geological conditions of Chang7 lacustrine shale oil reservoir in Yanchang Formation of Ordos Basin were studied by geochemical analysis, well logging, X ray diffraction, SEM, etc. The results show that the Chang7 lacustrine shale was well developed, and it can be divided into three types including ＂sand-shale interbed＂, ＂thick shale of class Ⅰ ＂ and ＂thick shale of class Ⅱ＂, based on the lithological combination and geochemical characteristics. The Chang7 lacustrine shale extends widely with large thickness, which provides the basic geological conditions for shale oil accumulation. The shale has high content of brittle minerals which are necessary for shale oil exploration and development. High abundance of organic matter, fine organic matter types and appropriate thermal stage of the shale, lay a material foundation for shale oil accumulation. Although the Chang7 shale is very tight, micro-fractures can bee found under SEM, and many thin sand interlayers with better physical properties are well developed in the central part of the basin. Analytical data display that the Chang7 shale has good oil-bearing property and some extent of gas, and the thin sand interlayers show strong fluorescence under ultraviolet light owing to adequate oil source. Based on the geological conditions and oil-gas bearing properties, ＂sand-shale interbed＂ area are considered as the most favorable target for shale oil exploration. Compared with ＂class Ⅱ shale＂, ＂class Ⅰ shale＂ has better conditions of hydrocarbon generation, stronger brittleness, much more micro-fractures and better oil-gas bearing properties, so it is considered as the second favorable target for shale oil exploration.

关 键 词：页岩油 薄砂岩夹层 地质条件 延长组 鄂尔多斯盆地 

分 类 号：P593[天文地球—地球化学]