柴达木盆地地壳深部构造特征及油气勘探新领域

柴达木盆地从20 世纪50 年代以来, 已探明三大油气区: 西南尕斯库勒一带的第三系油气区, 北部冷湖、鱼卡、南八仙一带的侏罗系油气区以及东部三湖地区的第四系天然气区。但未来的油气勘探领域在哪里, 这是人们十分关注的问题。盆地榴辉岩、镁铁-超镁铁岩的发现和盆地边缘大量金矿的分布, 以及盆地中膏盐、白云岩、伊利石、锶矿床等的存在则表明了盆地广泛存在地幔流体活动。地震测深结果显示: 柴达木盆地中地壳广泛发育低速- 高导层, 这是无机油气的发生器。分析中地壳低速- 高导层与深大断裂分布关系, 大断裂与不整合面、浅层断裂及储集层的配套关系, 对寻找大油气田具有重要指导意义。研究表明, 柴西地区深部花岗岩及其风化壳是未来石油勘探的重 点, 而盆地东部三湖地区深部则是寻找大气田的有利靶区。

Deep crust structural features and new targets of petroleum exploration in Qaidam Basin

Three oil-gas bearing regions have been proved in Qaidam Basin since the 1950＇s, including Tertiary oil filed in west, Jurassic oil field in north and the Quaternary gas field in east. It is a problem concerned by the petroleum geologists where the new targets are for the further exploration. The discoveries of eclogite, ultramafite and gold mine in the periphery of the basin and gypsum-salt, dolomite, illite and strontium mine in the basin indicate the existence of mantle fluid activity. The seismic sounding result shows that low velocity-high conductive layers widely developed in the mid-crust of Qaidam Baisn. The analyses of the relationships between the low velocity-high conductive layers and discordogenic fault, between the fault and the unconformity and between the shallow fault and the reservoir take a significant part in looking for large oil and gas fields. The research shows that the further exploration should be stressed in deep granite and weathered crust in Chaixi area, and the deep of Sanhu area is the favorable target for looking for large gas fields.