柴西地区古近系—新近系含油凹陷构造特征与勘探领域

Structure features and exploration potential of the Paleogene-Neogene depressions in Western Qaidam Basin

受新生代东昆仑造山带构造活动的影响,柴达木盆地柴西地区构造变形强烈,分区性明显,可划分为东昆仑山前压扭冲断带、茫崖凹陷(浅层为英雄岭反转构造带)和大风山凸起三个构造单元。该区古近系—新近系高原咸化湖盆油气总资源量约为25×108t,有效烃源岩面积占同期湖盆面积的53%,为一典型的富油气凹陷,剩余资源量丰富,勘探潜力大。根据富油气凹陷的勘探理念,结合勘探程度及勘探技术现状分析,提出英雄岭反转构造带、柴西南地层岩性圈闭、阿尔金山前盆缘古隆起和茫崖凹陷及周缘致密油(气)藏为下步勘探的四大领域。

By influence of tectonic activity of the Cenozoic Eastern Kunlun orogenic belt,the Western Qaidam Basin has deformed strongly.With regional structural feature,this part can be divided into compression-shear thrust belts in the piedmont of the Eastern Kunlun range,Mangya depression with the Yingxiong Mountains reverse structural belts in the shallow layers,and the Dafengshan Salient.The total hydrocarbon resources in the Paleogene-Neogene plateau saline lacustrine basin are about 25×108t in the Western Qaidam Basin,among which the area effective hydrocarbon source rock amounts to 53%.This region is a typical hydrocarbon-rich depression with abundant surplus resources and great exploration potential.According to the exploration concept of hydrocarbon-rich depression,combined with the analysis of exploration degree and exploration technology,we propose the inverse structural zones in Yingxiong Mountains,lithologic strata in southwest of Qaidam Basin,the paleo-uplift in the piedmont of Altun Mountains,and the Mangya Depression with the periphery dense oil areas as four exploration fields.