摘要
鄂尔多斯盆地为大型富油气叠合盆地,发育奥陶系海相、石炭—二叠系海陆过渡相和三叠系湖相等多套页岩层系,具备页岩气形成的基本地质条件。为弄清该盆地页岩气的勘探潜力,通过野外地质勘查、岩心观察、老井资料复查,结合有机地球化学和岩石学分析、含气量测试、等温吸附曲线测定等实验结果,对其页岩气勘探潜力进行了初步评价。结论认为:①该区中奥陶统平凉组页岩分布范围和厚度较大,已进入大量生气阶段,但有机质丰度偏低,不利于页岩气成藏;②上三叠统延长组长7段页岩分布范围较广,厚度介于15～40m,有机质丰度很高,处于大量生油阶段,页岩气主要为热成因的伴生气,成藏条件较致密油要差;③石炭—二叠系页岩分布范围广,厚度介于50～150m,有机质丰度较高,处于大量生气阶段,含气量介于0.21×108～1.0×108 m3/t,页岩气勘探潜力最大。
The Ordos Basin is a large superimposed basin with abundant oil and gas,where multiple sets of shale sequences are well developed including the Ordovician marine facies,Carboniferous-Permian transition facies,and Triassic lacustrine facies,which provides basic geological conditions for shale gas formation.In order to make clear the exploration potential of shale gas in this basin,a preliminary evaluation is conducted through field geological surveying,core observation,and old-well data re-examination,in combination with organic geochemistry and rock analysis,gas content measurement,and isothermal adsorption curves.The following conclusions are presented herein.(1) In the Middle Ordovician Pingliang Formation,the shale rocks are distributed widely with great thickness;although a great volume of gas is at the generation stage there but the organic matter abundance is so low that shale gas pooling becomes difficult.(2) In the Yan-7 of the Upper Triassic Yanchang Formation,shale rocks are also distributed widely with the thickness between 15 and 40 m;the organic matter abundance is quite high and a huge volume of oil is at the generation stage there;shale gas belongs to the associated thermogenic gas and its pooling condition is worse than that of the dense oil reservoirs.(3) Shale rocks in the Carboniferous-Permian formations are distributed widely with the thickness between 50 and 150 m;the organic matter abundance is rather high and a large volume of shale gas is at the stage of generation with the gas contents at 0.21-1.08 m3/t,which reveals a great potential for shale gas exploration.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2011年第12期40-46,125-126,共7页
Natural Gas Industry
基金
国家科技重大专项全球油气资源评价研究项目(编号:2008E-0502)
