羌塘盆地油气勘探前景展望

羌塘盆地为中生代大型的海相残留型构造盆地。盆地的南北缝合带及中央隆起带,宏观上可视为三条构造活动带,其间所夹持的两个相对稳定的地块,特别是南、北坳陷中部的两个复向斜区,是油气勘探的主攻方向。上三叠统—上侏罗统是盆地内的沉积主体,“两坳夹一隆”的古构造格局控制了沉积和烃源层的发育和展布。生物礁、滩多分布在高隆起周缘的碳酸盐岩台地上,发育于各组段中,但以侏罗系布曲组及索瓦组相对集中。盆地内发育有上三叠统肖茶卡组、中侏罗统布曲组和夏里组以及上侏罗统索瓦组四套主要烃源层,估算盆地的总生烃量为9930.92×108t,远景资源量为52.95×108t,具有雄厚的找油物质基础。盆地内发育了四套生储盖组合,其中以侏罗系(组合Ⅲ)布曲组—夏里组亚组合最好,是盆地主要的勘探目的层。应用多种方法综合研究和评价认为,北羌塘坳陷金星湖—东湖—托纳木地区和南羌塘坳陷比洛错东—土门地区是最有利的含油气远景区。

Oil and Gas Prospect for Exploration in Qiangtang Basin

Qiangtang Basin that is virgin for exploration is the biggest Mesozoic remnant marine sedimentary basin in Tibet plateau China.The central uplift and the northern and southern depressions controlled development of sedimentation and source rocks. Four formations of source rock have been recognized in Upper Triassic-Upper Jurassic carbonate sedimentary rocks. There are four sets of source-reservoir-cap assemblages in the rocks, in which Assemblage Ⅲ have the best hydrocarbon potential. Primary estimation indicated that the total hydrocarbon-generating quantity is more then 993.092×109t and the prospective resources is about 5.295×109t in the whole basin. It is suggested that Jinxinghu-Donghu-Tuonamu area in the northern depression and Biluoco-Tumen area in the southern depression are the most favorable targets for exploration in the basin.