【摘要】 根据白垩系底部不整合面的成因机制和地震反射特征,将研究区的不整合分为四种类型,不同类型的不整合对研究区油气运聚作用也各不相同。白垩系底部不整合面上下地层的岩性配置可分为五种类型:Ⅰ型,不整合面之上为砂砾,其下依次为泥岩、砂岩;Ⅱ型,不整合面之上为砂岩,其下依次为泥岩、砂岩;Ⅲ型,不整合面之上为砂砾岩,其下依次为泥岩、砂砾岩;Ⅳ型,不整合面之上为砂岩,其下依次为泥岩、砂砾岩;Ⅴ型,不整合面之上为砂砾岩,其下依次为泥岩、砂岩、砂砾岩。其中,Ⅰ型、Ⅱ型对本区油气运聚最为有利,白垩系底部不整合与断层共同构成了良好的输导通道,不整合之下的淋滤带是较好的运移通道,在其上风化粘土层的遮挡下,油气可有效地横向运移,喜马拉雅运动后期产生的正断层切割不整合底部的砾岩及上覆大套砂岩,向上快速输导油气。白垩系底部不整合封堵油气成藏有三种模式,即粘土层封堵、淋滤带半风化泥岩封堵和淋滤带薄层泥岩封堵。更多还原

【Abstract】 According to origin mechanism and seismic reflectance on unconformity at Cretaceous bottom,unconformity in the studied area is divided into four types,each of which has different effects on the hydro-carbon migration and accumulation.Above and below the unconformity,there exist five types of lithology com-binations:TypeⅠincludes glutenite above it,mudstone and sandstone below it;TypeⅡsandstone above it,mudstone and sandstone below it;TypeⅢglutenite above it,mudstone and glutenite below it;TypeⅣsand-stone above it,mudstone and glutenitebelow it;TypeⅤgrit above it,mudstone,sandstone and glutenitebelow it.Among them,TypeⅠand typeⅡare the most favorable to oil and gas migration and accumulation in this area,for this unconformity and fault composed of channels of good conductivity,the leached zone below it acts as a better passage for petroleum migration,oil and gas can be migrated laterally and effectively by the weathered argillic horizon as a barrier above it.While the basal conglomerate and overburden thick sandstones cut by normal faults formed in late period of Himalayan movement have enabled oil and gas to migrate up-ward rapidly.The hydrocarbon reservoirs at Cretaceous bottom unconformity could be shaped by three styles of barriers such as argillic horizon barrier,leached zone half-weathered mudstone barrier and thin layer barrier.更多还原