不同古地貌单元水下分流河道沉积特征及其意义——以准噶尔盆地夏盐地区三工河组二段为例

Sedimentary Characteristics and Significance of Underwater Distri butary Channel in Different Paleogeomorphic Units: A case study of the second member of the Sangonghe Formation in Xiayan district,Junggar Basin

为详细解剖水下分流河道沉积特征,探讨其岩性圈闭意义,采用多参数分析方法,对水下分流河道微相沉积特征进行了分析,提出了发育于不同古地貌单元的水下分流河道微相砂体由于物性存在差异而对岩性圈闭的形成具有重要意义。研究结果表明:研究区三工河组二段发育古低凸和古沟槽2种古地貌单元,古沟槽发育反旋回叠置型水下分流河道,低凸翼部发育正旋回叠置型水下分流河道。正旋回叠置型水下分流河道砂体物性自下而上逐渐变差,在侧向对反旋回叠置型水下分流河道储集体构成侧向遮挡,有利于形成岩性圈闭。在此基础上建立了岩性圈闭模式,将该模式应用到油田预探井井位部署中,取得了很好的效果。

In order to dissect the characteristics of underwater distributary channel and discuss its significance for the formation of lithological traps,the sedimentary microfacies characteristics of an underwater distributary channel were analyzed by multi-parameter analysis. It is proposed that underwater distributary channel microfacies sandbodies which develop in different paleogeomorphological units are of great significance to the formation of lithological traps because of their different physical properties. The results show that two paleogeomorphological units are present in an ancient low rise and an ancient trench in the second section of the Sangonghe Formation in the study area:a non-rotating distributary channel was developed in the ancient trench,and a rotating distributary channel developed on the sides of the low rise. The physical properties of the normal cyclic underwater distributary channel sandbody gradually deteriorated from bottom to top,and lateral blockages formed at the sides of the reverse cyclic distributary channel reservoir,which was beneficial to the formation of lithological traps. On this basis,a lithological trap model was established and applied for the positioning of a pre-exploration well in the oilfield,and achieved good results.