北部湾盆地涠西南凹陷超压系统与油气运移

利用地震层速度、声波测井及各种录井资料研究北部湾盆地涠西南凹陷超压系统及油气运移 ,用以指导下一步油气勘探。研究发现主要生烃层段流沙港组二段泥岩的欠压实是形成异常高压的主要原因 ,异常压力主要分布于凹陷中心地区。最大压力封闭点及油的成熟门限深度可以区分异常高压层的作用 ,在生油门限以下的异常压力带中的快速压实段 ,是油气初次运移最有利的层段。研究发现本区存在两种油气运移方式 ,即向泥岩下方运移和侧向运移 ,最后指出勘探油气的有利地区

OVERPRESSURE SYSTEM AND MIGRATION OF HYDROCARBON IN WEIXI'NAN DEPRESSION IN BEIBU GULF BASIN

Seismic interval velocity, sonic logging and all kinds of logging data have been used to study the overpressure system and migration of hydrocarbon to instruct the future exploration in Weixi'nan depression in Beibu Gulf Basin,Offshore South China. The abnormal overpressure is mainly caused by the undercompaction of L 2 mudstone which is the dominating source layer and the abnormal overpressure distributes in the central area of the basin. The abnormal overpressure can be distinguished by the max pressure seal point and the depth of oil maturation threshold. The fast compacted unit in the abnormal pressure area blow the oil threshold is the favorable unit for primate migration. The research reveals that there are two modes of hydrocarbon migration—the migration to the underside of the mudstone and the lateral migration. At last the study shows the potential area for exploration.