羌塘盆地构造单元划分及含油气评价

利用羌塘盆地及其邻区的磁力、重力、电磁测深、地面地质调查、少量地震及有关化验分析数据,对盆地进行了构造单元划分和初步评价。该盆地以前泥盆纪变质岩为基底,其上可以划分出三套构造层:泥盆系-中三叠统为下构造层、上三叠统-侏罗系为中构造层、白垩-第三系为上构造层。运用多种资料综合分析后,在羌塘盆地划分出北羌塘坳陷、中央隆起带及南羌塘坳陷等三个二级构造单元,并进一步细分出12个三级构造单元。通过石油地质基本特征的研究,对12个三级构造单元进行了含油气远景初步评价,指出吐坡错-白滩湖深凹陷和蒂让碧错-土门凹陷为有利的含油气单元,应作为盆地油气勘探的重要目标。

The Classification of Structural Element in Qiangtang Basin and the Preliminary Evaluation

The classification of structural element and preliminary evaluation of Qiangtang basin are performed based on its mag-netic,gravitational,electromagnetic sounding,surface geologic survey and a few seismic information as well as related experimental analysis data.Above the pre-Devonian basement,this basin can be divided into three structural zones from bottom to top,i.e.,Devonian-Middle Triassic,Upper Triassic-Jurassic and Cretaceous-Tertiary.Through composite analyses of various data and informa -tion,the basin can also be divided into three grade-II elements such as north Qiangtang depression,central uplift belt and south Qiangtang depression,which can further be subdivided into12elements of grade-III.According to their petroleum geologic fea-tures,this paper presents preliminary evaluations of petroliferous potentials of these12elements,and points out that Tupocuo-Bai-tanhu deep sag and Dirangbicuo-Tumen sag are favorable petroliferous elements and could be as major targets for oil-gas explo-ration in Qiangtang basin.