富油凹陷油源断裂输导能力研究

Oil-migrating faults are important longitudinal channels for the transporting of petroleum in oil-rich sags, which play an efficient role in vertical migration and distribution of oil and gas, as a result, study on those factors which have influence on faults' conducting ability and the methods about how to estimate the conducting ability of faults qualitatively and quantitatively have great theoretical and practical significances. In this project we are about to take Zhanhua sag and Bozhong sag as the research objects, start with the relationship between faults' static features and the distribution of oil and gas, select those oil-migrating faults highly related to oil or gas distribution, then put emphasis on how different faults and geological factors control the process of oil and gas transporting through those faults, find out influences that restrict the ability, efficiency of longitudinal transporting and strata of accumulation, evaluate the effectiveness of using geological parameters to characterize the conducting ability of faults with the help of physical simulation experiments; through analysis of faults in typical regions full of oil and gas, set up several qualitative and quantitative methods to estimate the ability of faults to conduct oil and gas, establish the patterns of oil or gas migration through faults.

油源断裂是富油凹陷油气纵向运移的重要通道，其输导能力对油气的垂向运移及油气分布起重要作用，剖析油源断裂输导能力的影响因素，探讨断裂输导油气能力定性-定量评价方法，具有较高的理论及实践意义。本项目拟以渤海湾盆地新近系油气十分富集的沾化、渤中凹陷为研究对象，从断裂静态特征与油气分布关系入手，优选出与油气分布紧密相关的油源断裂，综合考虑断裂特征及地质条件对断裂输导油气能力的控制作用，明确制约断裂垂向输导油气能力、效率和聚集层系的影响因素，结合物理模拟实验评价地质参数表征断裂输导能力的有效性，提出断层输导油气能力定性-定量评价方法，建立油气沿断裂运移聚集模式。

油源断层是富油凹陷流体垂向输导的重要通道，对油气的大规模纵向运移、聚集及分布起着重要的作用，明确断层输导能力影响因素及定量评价方法，具有较高的理论及实践意义。本项目主要以渤海湾盆地渤中、沾化等凹陷为研究对象，从断裂的静态特征和油气分布关系入手，研究了断层活动性、断层封闭能力、断-盖配置和断-砂选择性充注对断层油气纵向输导能力的影响，结合输导能力物理模拟实验，提出油源断层油气输导能力评价公式，建立富油凹陷断裂控藏模式。结果表明，断层级次与油气分布关系密切，富油凹陷油气主要沿一级和二级断层分布，且一级油源断层控制油气纵向富集层系。断层输导油气作用影响因素主要包括断层活动性、断层封闭性、断-盖配置和断-砂选择性充注。油气富集层系受控于油源断层差异活动，断层差异活动系数大且成藏期活动时间长，有利于浅部新近系油气富集；通过恢复成藏期的地层厚度、断层断距、泥质含量等参数，建立断层古侧向封闭性评价方法，只有小于成藏期和现今SGR下限的断层具有好的侧向封闭性；基于所受外部压应力和内部抗压应力的关系建立断层垂向闭合系数S，S大于0.95的断层具有好的垂向封闭性；断-盖配置关系是造成油气富集层系差异的重要因素，埕岛地区馆下段断接厚度大小控制了油气纵向上的分布层位；断-砂选择性充注影响了不同砂层之间的含油气性差异，主要受断层类别、砂体类型、断-砂匹配关系、与输导断层距离、烃源岩供烃能力和储层物性等因素控制。通过对断层输导能力影响因素研究，设计物理实验模型，将物理模拟实验结果与勘探实际相结合，建立了浅部层系断层输导油气能力的定量评价方法，评价结果与新近系油气富集程度匹配关系较好，评价方法可信。综合上述研究，建立了“近源供烃-断层垂向输导-通源T型”、“远源供烃-断-砂复合输导-断阶带式”和“远源供烃-砂体侧向输导-斜坡带式”3类富油凹陷断裂控藏模式，对断裂发育区的油气勘探具有一定的理论指导意义。