欢喜岭油田南部沙三段浊积扇成因分析

Analysis on genesis of turbidite fan of the Third Member of Shahejie Formation in the south of Huanxiling Oilfield

欢喜岭油田位于辽河坳陷西部凹陷南部,沙三时期浊积扇非常发育,通过对研究区大量的资料分析,并结合前人的研究成果、地理位置、古地貌、构造特征等综合因素,认为该区发育2种类型的浊积扇:湖底扇和滑塌扇。根据2种浊积扇体的沉积特征,又将它们分为内扇、中扇、外扇3个亚相。湖底扇是中期基准面上升的早期碎屑源区洪泛事件形成的重力流进入深湖区,沿湖盆短轴方向发育的浊积扇;滑塌扇是短期基准面下降期扇三角洲前缘发生准同生期滑塌在深湖区形成的浊积扇。浊积扇砂体易形成岩性或构造-岩性油气藏,是油气勘探的重要目标。

The Huanxiling Oilfield is situated in the south of West Depression of Liaohe Sag. The turbidite fan is developed extraordinary in period of the third member of Shahejie. Study shows that two kinds of turbidites fan are developed in this area:sublacustrine fan and slump fan. Based on the sedimentation characteristics of the two kinds of turbidite, it can be divided into three subfacies as inner fan, middle fan and outer fan. The sublacustrine fans of the studied area are the turbidite fans which gravity flows form from water-flooding event of debris source zone at the early stage of ascending medium-term base level rush in abyss and develop along minor axis of lake basin,slump fans of the studied area are the turbidite fans which are formed by the front edge of fan deltas occurs syndepositional epoch slump in abyss at the stage of descending short-term base level.The sand bodies of braided channel of turbidite fan can form lithologic oil reservoir or structural-lithologic oil reservoir easily and will be the central target of oil and gas exploration.