笔架盆地地质构造特征及油气勘探潜力
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摘要
笔架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三套地震层序;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。笔架盆地新生代发育经历了断陷、坳陷和区域沉降三个发育阶段。受神狐运动的影响,古新世—早渐新世为盆地形成时期-断陷阶段,由于受NW-SE地壳应力向拉张作用,产生了一系列NE向或NEE向断裂和彼此相间的地堑和半地堑,形成了笔架盆地的雏形。盆地内部充填了大量河湖相沉积。晚渐新世-中中新世为盆地发展期-坳陷阶段,受南海中央海盆扩张的影响,南海北部普遍下沉,盆地沉积类型也随之发生变化,陆相逐步过渡到海陆过渡相和海相。晚中新世-全新世为盆地成熟期-区域沉降阶段,盆地以稳定的半深海-深海相沉积为主。古近系以断陷陆相河湖相、三角洲相沉积为特征,分布范围较广,最大沉积厚度超过1700 m,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;笔架盆地具备一定的油气潜力。
Bijia basin is a Cenozoic sedimentary basin which locates in the south continent margin of South China Sea.The basin developed three seismic sequences with complex tectonic systems, the faults developed very much and extended alone NE,EW and NW directions,the faults can be divided into normal fault and shift fault,normal fault is the most important fault.The basin has three developing stages——graben period,depression period and regional subside period. Affected by the Shenfu movement,the basin formed many NE direction faults and many small grabens from Paleocene to Eocene,during this period the basin accepted river-lake facies sediments.Afected by the spreading of the central basin of South China Sea,Bijia basin depressed and accepted transition facies or marine sediments from late Oligocene to middle Miocene.Late Miocene was the regional subsiding stage,the basin accepted mid-deep sea to deep sea sediments.Its thickness of graben sediments is more than 1700m,it can generated hydrocarbon,the basin has good reservoir and seal condition,the migration condition is also good,so the basin has good oil-gas potential.
Bijia basin is a Cenozoic sedimentary basin which locates in the south continent margin of South China Sea.The basin developed three seismic sequences with complex tectonic systems, the faults developed very much and extended alone NE,EW and NW directions,the faults can be divided into normal fault and shift fault,normal fault is the most important fault.The basin has three developing stages——graben period,depression period and regional subside period. Affected by the Shenfu movement,the basin formed many NE direction faults and many small grabens from Paleocene to Eocene,during this period the basin accepted river-lake facies sediments.Afected by the spreading of the central basin of South China Sea,Bijia basin depressed and accepted transition facies or marine sediments from late Oligocene to middle Miocene.Late Miocene was the regional subsiding stage,the basin accepted mid-deep sea to deep sea sediments.Its thickness of graben sediments is more than 1700m,it can generated hydrocarbon,the basin has good reservoir and seal condition,the migration condition is also good,so the basin has good oil-gas potential.
引文
[1]吴进民．新生代盆地图，南海地质地球物理图集[M]．广州：广东地图出版社，1987
[2]姚伯初．南海西南海盆的海底扩张及其构造意义[J]．南海地质研究(九)．1997，20～36
[3]宋海斌，郝天珧，江为为等．南海地球物理场特征与基底断裂体系研究[J]，地球物理学进展，2002，第17卷，第1期：24～33
[4]彭大钧，陈长民等．南海珠江口盆地深水扇系统的发现[J]．石油学报，2004，Vol．25，No．5：17～23
[2]姚伯初．南海西南海盆的海底扩张及其构造意义[J]．南海地质研究(九)．1997，20～36
[3]宋海斌，郝天珧，江为为等．南海地球物理场特征与基底断裂体系研究[J]，地球物理学进展，2002，第17卷，第1期：24～33
[4]彭大钧，陈长民等．南海珠江口盆地深水扇系统的发现[J]．石油学报，2004，Vol．25，No．5：17～23
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