摘要:利用地表露头、岩心、薄片和测井资料，对鄂尔多斯盆地南部长7油层组陆相页岩层系天然裂缝的成因类型、发育特征和主控因素进行研究。按地质成因，鄂尔多斯盆地南部长7油层组页岩层系的天然裂缝可以分为构造裂缝和成岩裂缝两大类，其中构造裂缝主要包括剪切裂缝和张性裂缝；成岩裂缝主要包括层理缝、页理缝和收缩裂缝。不同岩性中的天然裂缝发育情况明显不同，致密砂岩中以构造裂缝为主，层理缝仅在粉砂岩和局部细砂岩中发育；页岩和凝灰岩中页理缝、层理缝和构造裂缝均比较发育。不同类型的天然裂缝主控因素明显不同，构造裂缝的发育主要受岩性和岩石力学层层厚控制；砂岩中层理缝的发育主要受碳质纹层、粘土矿物转化程度等因素控制；凝灰岩中层理缝的发育主要受刚性玻屑脱玻化作用的控制；页岩中页理缝的发育主要受纹层、TOC含量和黄铁矿含量的控制。
关键词: 天然裂缝/
发育特征/
主控因素/
页岩油/
长7油层组/
鄂尔多斯盆地
Abstract:Using outcrops, cores, thin sections and well logs, the paper studied the genetic types, developmental characteristics and main control factors of natural fractures in the terrestrial shale strata of the 7th member of the Yanchang Formation(Chang 7) in the southern Ordos Basin. In terms of geological origin, the natural fractures developed in the shale series of Chang 7 in the southern Ordos Basin can be divided into tectonic fractures and diagenetic fractures, with the former including high-dip angle shear fractures, low-dip angle shear fractures and tensile fractures. The diagenetic fractures mainly include bedding fractures, lamellation fractures and shrinkage fractures. The development of natural fractures in different lithologies is obviously different. The natural fractures in tight sandstones are dominated by tectonic fractures, the bedding fractures are only developed in siltstones and local fine sandstones. In shales and tuffs, lamellation fractures or bedding fractures and tectonic fractures are all developed. The main controlling factors of different types of natural fractures are obviously different. The development degree of tectonic fractures is controlled by lithology and the thickness of rock mechanical stratigraphy. The development degree of bedding fractures in sandstones is mainly controlled by the degree of carbonaceous interlayer development and clay mineral transformation. The development degree of bedding fractures tuff is mainly controlled by rigid glass chip contents. The development degree of lamellation fractures is mainly controlled by the lamina, TOC content and pyrite content.
Key words:Natural fractures/
Development characteristics/
Main controlling factors/
Shale oil/
Chang 7 oil formation/
Ordos Basin
PDF全文下载地址:
http://www.dzkx.org/data/article/export-pdf?id=1b1dd999-fb4b-4df9-95d6-1fdcb819068b
