渤海湾盆地冀中坳陷大柳泉构造不整合输导油气能力的定量表征

Quantitative characterization of unconformity migration capacity of the Daliuquan structure in Jizhong Depression,Bohai Bay Basin

在不整合输导模式研究的基础上,定量表征了不整合输导油气能力。不整合主要通过水进层的连通孔隙系统和半风化岩石层的孔—缝系统输导油气,平面上存在发散运移和汇聚运移2种模式,垂向上则存在顺层运移和窜层运移2种模式。不整合输导油气能力主要受不整合类型、不整合结构及其物性、不整合面倾角、不整合交会叠置程度、不整合发育规模、源储距离、油气黏度以及油气运移动力等因素的共同影响。基于达西定律,综合各项影响因素,建立了具有实际地质意义的不整合输导油气能力定量表征公式,并利用该公式对渤海湾盆地冀中坳陷廊固凹陷大柳泉构造古近系沙三段与沙四段之间不整合的输导能力进行了评价。结果表明,该不整合输导油气能力具有自大兴断层至牛北斜坡带逐渐增强的变化规律,且存在3个优势运移路径,这些路径上的地层圈闭可作为有利的勘探目标。定量评价结果与实际地质情况具有较好的吻合性,表明所建立的不整合输导油气能力定量表征方法具有较好的适用性。

Based on the research of the unconformity migration patterns,the unconformity migration capacity was characterized quantitatively.The unconformity hydrocarbon migration is mainly through the connected pore system of the water-entering layer and the pore-crack system of semi-weathered rock layer.Two kinds of divergent migration modes and gathering migration modes exist in the horizontal direction,while two kinds of consequent migration modes and channeling layer migration modes exist in the vertical direction.The unconformity migration capacity is affected jointly by unconformity type,unconformity structure and properties,inclination of unconformity surface,unconformity intersection overlay degree,unconformity scale,distance between oil source and reservoir,hydrocarbon viscosity,hydrocarbon migration motive force and other factors.Based on Darcy＇s Law,the quantitative characterization formula of unconformity migration capacity with actual geological significance was established after taking several factors into consideration.The unconformity migration capacity between the third section and the four section of Shahejie Formation of Daliuquan structure of Langgu Sag in Jizhong Depression gradually strengthen from Daxing fault to Niubei slope,and there are three dominant migration paths.The stratigraphic traps on the paths can be favorable exploration targets.The quantitative evaluation results and the actual geological conditions have a good agreement,which shows that the quantitative characterization method of unconformity migration capacity established has good applicability.