鄂尔多斯盆地延长期原型湖盆恢复及中部砂体成因

Reconstitution of original lake basin during Triassic Yanchang stage and sand body genesis in the center of Ordos Basin

根据大量钻井、露头及岩心资料,采用野外观察与室内研究相结合的方法,对鄂尔多斯盆地延长期湖岸线、深湖线、湖盆底形等进行了恢复,所恢复的长6湖盆中心位于正宁、甘泉、庙湾等地。东北部缓坡带主要发育三角洲砂体,西南部陡坡带主要发育辫状河三角洲及深湖区重力流(主要为浊积岩和砂质碎屑流)砂体;湖盆东北部发育浅水坡折带和深水缓坡型坡折带,西南部发育深水陡坡型坡折带,湖盆中心具有先向西南方向迁移,再向东北方向迁移的演化特点。在对三角洲砂体的勘探继续关注的同时,深水区及湖泛期砂体的勘探也应引起进一步的重视;受东部缓坡坡折带控制的地区和受西部陡坡坡折带控制的地区砂体的展布规律不同,应采取不同的勘探思路。

Based on large quantities of drilling,outcrop and core data,combined with field observation and laboratory study,the lake shoreline,deep lake line and the lake basin bed form were restored.The result shows that the lake basin center of Chang 6 period is located at Zhengning,Ganquan and Miaowan area.Delta sand bodies are developed in northeast gentle slope break zone,braided delta and gravity flow(mainly turbidite and sandy debris flow) in deep lake are developed in southwest steep slope break zone,shallow water slope break zone and deep water gentle slope break zone are mainly developed in the northeast,and deep water steep slope break zone is mainly developed in the southwest of the lake basin,with the center migrating to the southwest and then to northeast.Therefore,delta sand body is still the target of exploration in the future.Meanwhile,the exploration of sand body formed in deep lake and during flooding should be enhanced.The sand body distribution rule in the east gentle slope break zone is different to that in the west steep slope break zone,so we should adopt a different exploration strategy for different areas.