尖峰北盆地地质构造及油气勘探潜力

尖峰北盆地位于南海北部大陆边缘南部,是一个新生代沉积盆地。盆地发育了A、B、C、D、E5套地震层序;盆地内地质构造复杂,断裂发育,平面上断裂展布方向主要有NE向、近EW向和NW向三组,断裂可分为正断层及平移断层,以正断层为主。古新世—始新世为盆地形成时期即断陷阶段,盆地内部充填了大量河湖相沉积。渐新世—中中新世为盆地发展期即坳陷阶段,盆地沉积类型由陆相逐步过渡到海陆过渡相和海相。中中新世末期,盆地相对隆升,部分地区遭受剥蚀。晚中新世—全新世为区域沉降阶段,盆地及其围区以稳定的浅海-半深海相沉积为主。盆地早期河湖相、三角洲相沉积分布范围较广,最大沉积厚度超过4500m,具有一定的生烃能力;盆地储盖条件良好,油气运移条件良好;尖峰北盆地具备较好的油气潜力。

GEOLOGIC STRUCTURE OF JIANFENGBEI BASIN AND ITS PROSPECT FOR PETROLEUM EXPLORATION

Jianfengbei basin is a Cenozoic sedimentary basin which is located in the south continent margin of the South China Sea.This basin consists of five seismic sequences with complex tectonic systems.In the basin,faults are well developed and extend alone NE,EW and NW directions.They can be grouped under normal and shift faults.Normal fault is the most important.The basin has two developing stages:early graben period and late depression period.Affected by the Shenfu movement from Paleocene to Eocene,the basin gave birth to many NE or NEE faults and many small grabens,and during this period the basin accepted sediments of river-lake facies.Influenced by spreading of the central basin of the South China Sea from Oligocene to middle Miocene,Jianfengbei basin subsided and accepted transition facies or marine sediments.At the end of middle Miocene the basin uplifted and some parts of the basin were eroded.Late Miocene was a regional subsiding stage when the basin accepted shallow sea to deep sea sediments,which are distributed broadly and more than 4 500 m in thickness.Such sediments can generate hydrocarbon.The basin has good reservoir and seal condition and also good migration condition,so it has good oil-gas potential.