北部湾盆地涠西勘查区反转构造及其油气成藏意义

INVERSION STRUCTRURE AND ITS IMPLICATION TO HYDROCARBON ACCUMULATION IN WEIXI EXPLORATION REGION OF THE BEIBUWAN BASIN

在系统分析北部湾盆地涠西勘查区地震剖面的基础上,认为北部湾盆地涠西勘查区发育两期反转构造即渐新世末期及中新世末期反转构造。这两期反转构造形成断层型反转构造和褶皱型反转构造两类,它们的形成与北部湾盆地演化的区域应力性质及方向的调整有关。该反转构造一方面形成良好的圈闭条件,另一方面使早期形成的断裂重新活动,有利于油气运移。同时两期反转构造形成的圈闭与勘查区内主要的烃源岩生排烃高峰具有良好的时空配置关系,有利于油气聚集成藏,是寻找大中型油气田的首选目标。

It was indicated that there were two different inversion structures formed in two period based on analysis of seismic profiles in Weixi exploration region of the Beibuwan Basin.The first inversion structure was developed during the end of the Oligocene and the second during the end of the Miocene.These two periods of inversion structures can be divided into two types which were fault type and fold type.Formation of these inversion structures was resulted from the directional and qualitative adjustment of regional stress.On the one hand these inversion structures formed favourable traps,and on the other hand these inversion structures caused the early faults reactivation and made for oil migration.In addition,the formation periods of these inversion structures were matchable with the peak stages of hydrocarbon generation and expulsion.These inversion structures are preferred targets for finding giant-medium size of oil-gas fields.