摘要
为研究松辽盆地徐家围子断陷的断裂构造演化,搞清断裂在各个时期的活动特征,以及对地层沉积、储层改造和盖层保存的影响,从而分析其对天然气成藏的控制。笔者以地质时期作为断裂控藏作用的第一分类原则,对断陷期的构造解析利用最大断距相减法分析徐西断裂,认为徐西断裂在火石岭期是多条分段的小断裂,至沙河子期才连接成为一条大规模控陷断裂,此外还发现徐东走滑断裂带的东侧分支也是一条火石岭期和沙河子期就强烈伸展的断裂,具有与徐西断裂相似的控陷作用,于营城期卷入新生的走滑断裂带。由于T2断裂密集带的形成受到断陷层先存断裂的控制,本文利用坳陷层T2断裂密集带对深部断裂(T4和T41)再活动的映射关系,分别分析火山岩气藏的气源断裂和调整断裂。根据构造演化时期,将松辽盆地徐家围子断陷的断裂控藏作用分为以下几类:断陷期断裂活动控制沙河子组源岩和营城组储层的分布于活动强烈、古断距较大的控陷断裂上盘局部区域;营城组火山岩沿徐中断裂和徐东断裂带喷发,对成藏有利的火山岩相分布与徐中断裂和徐东断裂带附近;青山口期T41断裂选择性复活,在断裂附近形成大量新生裂缝改善火山岩储层物性,同时成为天然气充注的通道,在时空关系上具有储层形成与油气运移同时发生,和优质储层紧邻气源断裂的特征,对天然气成藏极为有利;反转期断陷中部及北部的断裂活动较弱,气藏多数得以保存。据此提出气源断裂——火山口联合控藏模式,其中本研究区的几条大规模断裂——徐西、徐中和徐东断裂带都具有多重控藏作用,同一条断裂在各构造演化时期的作用不同。
The purpose of this article is to study the evolution of Xujiaweizi rift depression in Songliao Basin and then anylysis its control on the accumulation of natural gas,so it is necessary to know how active faults controlled sedimentary,reservoir reconstruction and caprock preservation. We take geological period first into consideration to classify function of fault controlling reservoir,and use the maximum throw subtracting method to research Xuxi fault. Xuxi fault was composed of several single faults and not the whole fault in Huoshiling Stage,and connected the whole fault in Shahezi Stage. The east branch fault of Xudong strike-slip fault belt was active in Huoshiling Stage and Shahezi Stage,playing similar role in rift controlling as Xuxi fault,and involved in strike-slip in Yingcheng Stage. Because fault dense zones on T2 reflecting layer were controlled by pre-existing faults in rift stage,reactivation of pre-existing faults can be recognized by the relationship between pre-existing faults and fault dense zones,so we can find out which faults are gas-source faults and which faults destroyed gas reservoirs.According to the stages of structure evolution,functions of fault controlling reservoir in Xujiaweizi fault depression can be divided into several categories: faulting in the rift stage controlled sedimentary of reservoir rock and source rock,which deposit in hangingwall of strongly active faults that had relative large peleo-displacement; volcanic rock of Yingcheng Formation erupted along Xuzhong fault and Xudong Fault belt in order to form dominant volcanic facies; faults on T41 reflecting layer partly reactived,forming a lot of fractures to improve property of volcanic reservoir and being gas-source faults,and it has feature like simultaneous reservoir formation and gas migration,and neighbourhood between advantageous reservoir and gas-source faults,that benefited gas formation; most reserviors wasn`t destroyed in later stage because of weak faulting in northern and middle part of Xujiaweizi fault depression. So we present combined reservior pattern of 'gas-source faults and volcanic vents '. The several large-scale faults including Xuxi fault,Xuzhong fault and Xudong,had multiple functions of reservoir-controlling,and even the same fault has different function in every stage.
出处
《地质论评》
CAS
CSCD
北大核心
2015年第6期1332-1346,共15页
Geological Review
基金
国家自然科学基金项目(编号41272151)
东北石油大学研究生创新科研项目(编号YJSCX2015-004NEPU)的成果
关键词
徐家围子
断裂复活
断裂控藏
最大断距相减法
气源断裂
Xujiaweizi
fault re-active
fault control on reservior
maximum throw subtracting method
gas souce fault
