中拐凸起石炭系火山岩油藏特征及成藏模式新认识

Reservoir Characteristics of Volcanic Rock and Accumulation Model of Carboniferous in Zhongguai Uplift

针对中拐凸起石炭系南、北油藏高度差异大,试油普遍见水,油水关系复杂,油水过渡带大,油藏类型及主控因素认识不清的现状,对其构造特征、断裂组合关系、储盖组合特征及地层水特征等控藏因素进行了分析。研究认为:中拐凸起石炭系发育两类油藏,古隆主体地震反射杂乱,为受构造、断裂控制的块状油藏,周缘围斜区为层状反射特征,油藏为受不整合面或岩性遮挡的层状油藏。南部古隆形态完整,保存条件好,油藏高度大;北部地层剥蚀严重,古隆更高,分布范围缩小,充注程度不足,油藏高度不大;发育两级断裂,一级走滑断裂疏通油源,二级断裂控制油藏展布特征。南部主要发育火山角砾岩,储层物性好,有利于油气的聚集;北部则以火山熔岩为主,储层物性较南部略差;且南部盖层条件优于北部,对下伏石炭系油藏起到更好的封盖作用。研究区地层水为氯化钙水型,南部热液改造作用不明显,矿化度较低;北部沿断裂热液改造作用明显,矿化度较高;古隆主体热液改造作用弱,矿化度较周缘围斜区低。

Abstract:The height of the reservoir is different between the south and north in Carboniferous of Zhongguai uplift.Water is commonly seen in oil test,oil-water relationship is complex,transitional zone of oil-water is large,reservoir type and main control factors are not clear.Based on the analysis of reservoir-cap rock association and formation water characteristics of Carboniferous,it is believed that zhongguai uplft developped two types of reservoir:massive reservoir and layered reservior.The form of southern Paleouplift is integral,preserve condition is good,reservoir height is large,the erosion of northern strata is serious,and the distribution range is reduced,filling degree is insufficient.There are two stages of faults: strike-slip fault unchoke oil,the second-order fault controls the distribution features of reservoir.The soutern part maily develop volcanic breccia,in favor of hydrocarbon accumulation,the northern part is mainly volcanic lava,the reservoir property is slightly worse than that in the south,the conditions of caprock in the south are better than those in the north. The formation water in the study area is of calcium chloride type,Hydrothermal transformation is not obvious in the south,Hydrothermal transformation is weak in paleouplift,the salinity is lower than that of the peripheral periclinal area.