苏北地区古生界页岩气形成地质条件

根据岩心、钻井及露头等资料,以有机地球化学、储层岩石学等为重点,对苏北地区古生界下寒武统幕府山组、上奥陶统五峰组—下志留统高家边组、二叠系（孤峰组、龙潭组、大隆组）等3套富有机质泥页岩层系的页岩气形成地质条件进行初步分析,指出苏北地区古生界3套富有机质泥页岩层系分布面积广、厚度较大、有机碳含量高和热演化程度较高。与美国典型含气页岩相比,苏北地区古生界3套富有机质泥页岩层系有机质丰度与之相当,部分地区的成熟度偏高。苏北地区具有形成页岩气的良好物质基础,古生界页岩气勘探潜力大。另一方面,苏北地区古生界富有机质泥页岩普遍埋藏深,下古生界富有机质泥页岩成熟度普遍偏高,后期多期构造运动及岩浆活动强烈,这些因素对页岩气形成、富集及保存等有着重要影响。

Geological Conditions of Shale Gas Forming in Paleozoic Subei Area

With focus on the geo-chemistry and reservoir petrology,a preliminary study is performed on the geological conditions of shale gas forming in the three Paleozoic organic-rich shale strata in Subei area,including the lower Cambrian Mufushan Formation(∈1m),the upper Ordovician Wufeng Formation(O3w)-the lower Silurian Gaojiabian Formation(S1g),the Permian Formations(Gufeng Formation(P1g),Longtan Formation(P2l),Dalong Formation(P2d)),by using core,drilling and outcrop data.The results indicate the Paleozoic shales are widely distributed in Subei area,relatively thick,organic rich,and higher thermal mature.In comparison with typical United States gas shales,the three Paleozoic organic-rich shales in Subei area have equivalent organic content to those in United States,but the maturity of organic-rich shales in part of Subei area is higher than that of the shales in United States.In general,the organic-rich shales in Subei area are well comparable to those in the United States,indicating they have favorable geological conditions for forming shale gas reservoirs and great shale gas exploration potential.On the other hand,the Paleozoic organic-rich shales in Subei area have great buried depth,high thermal maturity and late multiphase tectonic movement and magmatic activity.The important effects of these factors on shale gas generation,accumulation and preservation need further study.