四川盆地下古生界存在页岩气的地球化学依据  

Geochemical evidence of shale gas existed in the Lower Paleozoic Sichuan basin

作　　者：王兰生[1] 邹春艳[1] 郑平[1] 陈盛吉[1] 张琦[1] 许斌[1] 李红卫[1] 

机构地区：[1]中国石油西南油气田公司勘探开发研究院

出　　处：《天然气工业》2009年第5期59-62,共4页Natural Gas Industry

基　　金：国家科技重大专项课题(2008ZX05004-005)的部分成果

摘　　要：四川盆地寒武系底部和志留系底部各存在一套良好的高成熟度、高有机质丰度、类型好的烃源岩,所生成的天然气均为腐泥型有机质形成的油型气,均可作为页岩气的勘探目标。下寒武统页岩烃源岩以川西南地区厚度最大,呈辐射状减薄,其累计厚度在100～400m之间,有机碳含量在0.2%～9.98%之间,平均值为0.97%;下志留统页岩烃源岩主要分布在川南、川东地区,累计厚度在100～700m之间,平均厚度为203m,其中黑色页岩厚度变化在20～120m之间,富含笔石,有机碳含量在0.4%～1.6%之间,有机质类型主要为腐泥型干酪根,生烃能力强,热演化程度高,已演化至过成熟阶段,目前生烃已近枯竭,但也说明它的生烃能力巨大,历史上曾经大量生成天然气。从其成熟度、运聚条件和矿物成分比较分析后认为:四川盆地页岩气勘探开发的首选目标应为川南下志留统页岩。There is a set of source rocks with high maturity,high abundance of organic matter and good types in Cambrian Bottom and Silurian Bottom respectively in the Sichuan basin where the produced natural gas both belongs to oil-type gas generated from sapropelic matter.They can be regarded as exploration targets of shale gas.The shale source rocks in the southwestern Sichuan basin,thinned in radial pattern,are the thickest with the total thickness 100-400 m and organic carbon content 0.2%-9.98% with an average value of 0.97%;The Lower Silurian shale source rocks are always distributed in the southern and eastern Sichuan basin whose total thickness ranges from 100-700 m with an average thickness of 203 m.Among them,the black shale is rich in graptolite whose thickness is between 20-120 m and organic carbon content 0.4%-1.6%,and it mainly has type I organic matter,strong hydrocarbon generation capacity and high thermal evolution degree almost evolved to overmature stage.Although their hydrocarbon generation capability is nearly exhausted at the present time,it still indicates that the huge amount of natural gas has been generated in geological history because of its high hydrocarbon generation capacity.This paper suggests that Silurian bottom shale in the southern Sichuan basin can be selected as the top target for shale gas exploration in the Sichuan basin by comparison analysis on maturity,oil and gas migration and accumulation condition and mineral composition.

关 键 词：四川盆地 寒武纪 志留纪 页岩气 勘探 目标 

分 类 号：P618.13[天文地球—矿床学]