湘中涟源凹陷下二叠统梁山组页岩气勘探前景

基于涟源凹陷二叠系梁山组泥页岩野外露头、钻井等资料，通过有机地化分析测试、X-衍射分析、扫描电镜观察、等温吸附等实验测试分析，系统研究了梁山组泥页岩的地质及地化特征、矿物组成、孔隙结构及吸附性能等。研究结果表明，梁山组有效泥页岩单层厚度为6.15~35.18 m；有机质丰度较高，多数大于1%，平均为1.77%；有机质类型主要为I型，岩石热解峰温Tmax（450~533℃）和镜质体反射率（1.51%~1.83%）表明泥页岩属于高成熟阶段富有机质泥页岩。泥页岩矿物组成以石英为主，黏土矿物含量次之，黏土矿物以伊利石为主，有利于改善泥页岩储集性能。孔隙类型多样，有机质孔、粒间孔、粒内孔及微裂缝为页岩气赋存提供空间。页岩吸附气含量达0.65 m3/t，具有一定的气体吸附能力。总体上梁山组泥页岩在涟源凹陷普遍发育且规模较大，特别是向斜区南部是页岩气有利勘探区。

Exploration Potential of Shale Gas in Lower Permian Liangshan Formation of Lianyuan Depression,Central Hunan

Based on outcrops and drilling data of Lower Permian Liangshan Formation shale in Lianyuan depression, its geological and geochemical characteristics, mineral composition, pore structure as well as gas adsorption capacity have been studied and discussed in this paper through using the organic geochemical test, X-ray diffraction mineral analysis, electron microscopy scanning, and methane isothermal adsorption. The results show that the shale reservoir of Liangshan Formation is 6.15-35.18m thick. The abundance of organic matter is mostly greater than 1%, with an average of 1.77%, and the organic matter type is mainly type I. The temperature of maximum pyrolysis output Tmax (450-533℃) and vitrinite reflectance Ro (1.51%-1.83%) indicate that the shale belongs to organic-rich shale in post-mature stage. The shale minerals are dominated by quartz and followed by clay minerals. The clay minerals are mainly illite, which is beneficial to improve the shale reservoir performance. With diverse pore types, the organic pores, intergranular pores and micro-cracks provide space for shale gas. The adsorption gas content of shale is 0.65 m3/t, and it has a good gas adsorption capacity. In a word, Liangshan Formation shale is generally developed and large in Lianyuan Sag, especially in the south of syncline areas, which are favorable for shale gas exploration.