内蒙古西部银额盆地石炭系—二叠系油气地质条件与勘探发现

Carboniferous-Permian petroleum conditions and exploration breakthrough in the Yingen-Ejin Basin in Inner Mongolia

通过开展石炭纪—二叠纪盆地形成演化、沉积充填、烃源岩分布与地球化学特征、烃源岩热演化史,以及石炭系—二叠系沉积之后的构造沉积演化与油气保存条件的综合研究,提出了银额盆地为石炭纪—二叠纪与中生代叠合盆地的新认识,查明石炭系—二叠系为陆内裂谷盆地沉积产物,发育多套厚度大、有机质丰度中等—高、干酪根类型以Ⅱ型为主、演化程度中等—高的良好烃源岩,明确了其油气地质条件。优选的油气远景区经国土资源部竞争性出让,企业加大勘探投入,于务桃亥勘查区拐子湖凹陷首钻(拐参1井)获初期日产原油51.67 m3、天然气7290 m3的工业油气流,温图高勒苏木勘查区哈日凹陷首钻(延哈参1井)获日产天然气9.15万m3(无阻流量)的工业气流及少量凝析油,实现了1955年勘探以来油气的重大突破。通过对2口油气突破井产层时代的厘定,以及油气源的对比,明确了油气产层时代为二叠纪,指明了石炭系—二叠系良好的油气资源前景,应为区内油气勘探的主要目的层。

Lots of geological and petroleum studies have been conducted in the Yingen-Ejin(YE)Basin in such aspects as the evolution of the Carboniferous-Permian basin,the sedimentary filling,the regional distribution and geochemical characteristics of source rocks,the thermal evolution history of hydrocarbon source rocks,and the tectonic and sedimentary evolution and hydrocarbon preservation after the Carboniferous-Permian deposition.Based on the achievements obtained from these studies,the authors hold that the Yingen-Ejin Basin is composed of superimposed basins composed of a Carboniferous-Permian continental rift basin and Mesozoic inland basins.Petroleum prosperity is proved by the existence of several Carboniferous-Permian source strata characterized by great thickness,moderate-high abundance of organic matter,the existence of main kerogen typeⅡ,and moderatehigh evolution stage.The preferred oil and gas prospecting areas were sold by the Ministry of Land and Resources,and the enterprises have increased the investment of the exploration.The first drilling hole(Guaican1st Well)of the Guaizihu depression in the Wutaohe exploration area obtained the initial daily production of51.67m3oil and7290m3natural gas(open flow potential)with a small amount of condensate gas,and the first drilling hole(Yanhacan1st Well)of the Hari depression in the Wentugaole exploration area received the industrial gas flow of91500m3daily production(open flow potential)with a small amount of condensated oil.These achievements realize the great breakthrough of oil and gas exploration which started in1955.Based on the age constraints on the oil and gas strata in the two wells and the comparison of oil and gas sources,the authors consider that the ages of oil and gas strata should be the Permian.Additionally,the Carboniferous-Permian strata should be the main objects of oil and gas exploration in that they have great prospects of resources.