黄河口凹陷东洼新近系油气富集规律研究

Hydrocarbon Enrichment of Neogene in the Eastern Sub-sag of Huanghekou Depression

为了揭示黄河口凹陷东洼新近系油气富集规律,对黄河口凹陷东洼油源断裂活动性、区域盖层发育情况、断裂与圈闭的接触关系等成藏要素进行了统计分析,发现控圈断裂在成藏期的断裂活动速率与研究区新近系油气富集程度呈正相关关系,盖层断接厚度与新近系油气富集程度呈负相关关系,断圈接触长度与新近系油气富集程度呈正相关关系。在此基础上,将已钻井的三项参数进行三角投图,按照油气富集程度进行分区并计算出各区间界限值,建立了黄河口凹陷东洼的新近系油气富集程度半定量判别方法。利用该方法对构造区未钻圈闭进行了评价,后续的钻探结果与钻前评价吻合,证明了该方法的有效性,并在黄河口凹陷东洼发现了第一个大型油气田。

The Eastern Huanghekou Sub-sag is located in the easternmost part of the sag,which belongs to the brink miniature sags.No breakthrough in exploration has been made for many years,and the predecessors have less research on its reservoir formation law either.In order to reveal differential enrichment of hydrocarbons in the Eastern sub-sag,this paper systematically studies the fracture activity,cap rock development,and the contact relationship between fracture and trap.The research findings are as the following.There was a positive correlation between the trap controlling fractures'activity velocity of accumulation period fracture and oil-gas enrichment of the Neogene stratigraphic,a negative correlation between cap rock-fault contact thickness and oil-gas enrichment of the Neogene stratigraphic,a positive correlation between trap-fault contact length and oil-gas enrichment of the Neogene stratigraphic.On this basis,by analyzing the drilled well data with the triangle chart board method,and then partitioning the triangle chart with oil-gas enrichment level,this paper established a semi-quantitative method to estimate the fracture controlling affection on reservoir forming.This evaluation method guides the next well position deployment.The follow-up drilling results conform to the experimental ones,which proved the effectiveness of the method and discovered the first large oil fields in the Eastern sub-sag.