祁连-走廊-贺兰坳陷区石炭系油气勘探有利区块选择

SELECTION OF FAVOURABLE BLOCKS FOR CARBONIFEROUS HYDROCARBON EXPLORATION IN QILIAN-ZOULANG-HELAN DEPRESSION

孙冬胜 白玉宝 蔚远江

Sun Dongsheng Bai Yubao Yu Yuanjiang

祁连-走廊-贺兰坳陷区在石炭纪发育为一大型坳陷型盆地,以三角洲和滨浅海相为主要沉积岩相类型。石炭系受后期改造影响较大,华力西末期石炭系盆地萎缩,但构造格局基本未变,仍为坳陷盆地;印支期盆地遭受剥蚀,强烈的褶皱不但使二叠系剥蚀夷尽,石炭系也遭受了不同程度的剥蚀;燕山期盆地开始解体,但在中生界分布区石炭系保存有利;喜山期残存盆地深埋,石炭系仅零星残存在造山带的低洼地带。巴颜浩特盆地的东部坳陷和南部坳陷,石炭系残留面积大,沉积厚度大,烃源岩类型齐全,既有暗色泥岩又有碳酸盐岩和可燃有机岩,具有较高的生烃潜力;由于油气形成较晚,第三纪构造变动又不强烈,地震剖面上具坳陷特征,加之上有侏罗系的覆盖,因之保存条件最好,为油气勘探的首选区。

Qilian-Zoulang-Helan Region developed into a large depressed basin in Carboniferous Period.The main sedimentary facies were delta,shore and shoal sea facies.The basin underwent considerable reformation in the late stage of Carboniferous,it shrank in the end of Variscan Period,but its tectonic framework didn't change much;in Indo- Chinese Epoch,the basin was denuded seriously,Permian System was completely denuded due to strong fold,and Carboniferous System was also denuded in different degrees;in Yenshen Period,the basin began to disintegrate,but the Mesozoic distribution areas were favourable for preservation of Carboniferous System.The residual basins were deeply buried in Himalayan Period,and the Carboniferous System was piecemeal distributed in the depressed belts of orogenic zone.In eastern and southern depressions of Bayanhott Basin,the remained Carboniferous System is larger and thicker,and has more types of hydrocarbon source rocks with higher hydrocarbon generation potential,it should be taken as target area for oil exploration.

10.11743/ogg20000120