南祁连盆地下日哈坳陷上三叠统泥页岩地球化学特征及生烃潜力评价  

Geochemical Characteristics and Evaluation of Hydrocarbon-generating Potential of the Upper Triassic Mud Shale in Xiariha Depression of South Qilian Basin

作　　者：李成福 陈磊 刘钰 韦钦杰 肖龙 范文科 云启成 LI Chengfu;CHEN Lei;LIU Yu;WEI Qinjie;XIAO Long;FAN Wenke;YUN Qicheng(Qinghai Bureau of Geological Survey,Xining 810000,Qinghai,China;Qinghai Coal Geological Exploration Institute,Xining 810000,China;Formation Testing Company of CNPC Xibu Drilling Engineering Company Limited,Karamay 834000,Xinjiang,China)

机构地区：[1]青海省地质调查局,青海西宁810000 [2]青海煤炭地质勘查院,青海西宁810000 [3]中国石油集团西部钻探工程有限公司试油公司,新疆克拉玛依834000

出　　处：《西北地质》2020年第4期153-162,共10页Northwestern Geology

基　　金：青海省清洁能源矿产专项资金勘查项目“青海省天峻县下日哈坳陷页岩气调查评价”(2018137088kc052)。

摘　　要：下日哈坳陷是南祁连盆地中油气地质工作程度较低的地区之一,南祁连盆地发育石炭系暗色泥(灰)岩、下二叠统草地沟组暗色灰岩、上三叠统尕勒得寺组暗色泥岩和侏罗系暗色泥页岩4套烃源岩系,其中三叠纪烃源岩厚度较大,有机质丰度属于低中等,有机质成熟度适中,具有一定的生烃潜力和形成页岩气的地质条件。为了进一步认识下日哈坳陷上三叠统泥页岩生烃潜力,通过下日哈凹陷地质调查井和地表采集的样品,开展了上三叠统泥页岩分布、有机质丰度、有机质类型、有机质成熟度、矿物组成、储集特征和含气显示等页岩气地质条件的综合研究,认为下日哈凹陷地区上三叠统暗色泥页岩发育分布广、厚度大、有机质丰度中等、Ⅱ—Ⅲ型干酪根类型具有良好的生烃潜力;暗色泥页岩中脆性矿物的含量较高,黏土矿物以伊利石和绿泥石为主,利于吸附气的聚集和后期压裂改造形成裂缝;暗色泥岩物性较好,矿物粒间孔、次生溶蚀孔、有机质孔和微裂缝等孔(缝)隙发育,具有良好的储集条件,且在钻井岩心中上三叠统见到了异常显示,指示了下日哈凹陷地区上三叠统具有较好的页岩气生烃潜力,是南祁连盆地值得探索的油气新领域。Xiariha depression is in the southern Qilian Basin with relatively low degree of geological investigation in oil and gas.There are four sets of source rocks in this area:Carboniferous dark mudstone,Caodigou formation Lower Permian dark mud shale,Garaefersi formation Upper Triassic dark mudstone and Jurassic dark mudstone.Triassic source rock is of favorable conditions for hydrocarbon-generating potential and shale gas considering its thickness,content and maturity of organic matter.The authors carried out comprehensive studies on the distribution of Upper Triassic mud shale,the abundance,type and maturity of organic matter,the mineral composition,the reservoir property and the gas indication etc.to further understand the hydrocarbon-generating potential of Upper Triassic shale in Xiariha depression with the help of geological survey wells and coalfield drilling.It is held that the Upper Triassic dark mud shale in Xiariha depression has the characteristics of wide distribution,large thickness,medium abundance of organic matter and good hydrocarbon generating potential in TypeⅡand TypeⅢ.The content of brittle minerals are much higher in dark mudshale with the clay minerals of illite and chlorite,conducive to the accumulation of adsorbed gas and the formation of aractured fracture.Dark mudstone has good physical properties with mineral pore,secondary dissolution pores,organic pore and micro-fractures well-developed,providing good reservoir conditions.Furthermore,the abnormal indication of core samples suggests that shale gas in South Qilian Basin has hydrocarbon-generating potential and is worth exploring.

关 键 词：南祁连盆地 下日哈坳陷 上三叠统 页岩气 地球化学特征 生烃潜力 

分 类 号：P618.11[天文地球—矿床学]