摘要
伦坡拉盆地为西藏地区唯一发现工业油流的古近系断拗型陆相残留盆地。勘探实践表明,早期对该盆地构造-沉积模式与油气成藏关系认识不够一定程度上制约了勘探,为理清二者关系并落实有利勘探方向,本文对该盆地的构造、沉积特征及成藏条件进行分析。盆地南北向可划分为缓坡带、深凹带、陡岸带3个构造带;识别出河流-冲积扇、扇三角洲、湖泊、水下扇4种沉积体系,其中在缓坡带发育河流-冲积扇、扇三角洲沉积体系,深凹带发育湖相沉积体系,陡岸带发育水下扇沉积体系;盆地存在2种沉积体系组合:缓坡带(河流)冲积扇-扇三角洲-滨浅湖相沉积体系组合,陡岸带水下扇-半深湖(深湖)-滨浅湖相沉积体系组合;可用"双向物源、缓坡扇三角洲、陡坡水下扇"构造-沉积模式解释。在缓坡带,应寻找扇三角洲前缘岩性隐蔽性油藏;在陡岸带,有可能发现构造-岩性复合型隐蔽性油藏。盆地具有多种潜在有利勘探目标类型,展现出较好的勘探前景。
The Lunpola basin,a continental residual basin of the Paleogene fault-depression type,is the only in Tibet with discovered industrial-oil.Early exploration proved that the insufficient understanding of the relationship between the structure-sedimentary model and hydrocarbon accumulation has restricted the exploration to some degree. To clarify this relationship and find out the favorable exploration direction,this work made the comprehensive analysis of tectonic-sedimentary characteristics and reservoir conditions of this basin. The results suggest that in north-south direction,this basin can be divided into a gentle slope zone,deep sag zone,and abrupt slope zone,three tectonic units. Four sedimentary systems are recognized,which are river-alluvial fan,fan delta,lake,and subaqurous fan,of which the river-alluvial fan and fan delta sedimentary systems are located in gentle slope zones,lacustrine depositional system in a deep sag zone,and subaqurous fan in the abrupt slope zone. There are also two integrated patterns of sedimentary systems：alluvial fan-fan delta-shore shallow lake sedimentary system in the gentle slope zone,and underwater fan-half deep lake（ deep lake）-shore shallow lake in the steep slope zone. Three structure-deposition models can characterize this basin,which are the bidirectional provenance,fan delta in gentle slope zone,and subaqurous fan in the abrupt slope zone. In the gentle slopes,lithological subtle reservoirs in the fan delta front sand bodies should be the main targets. While it is possible to find structural-lithologic complex subtle reservoirs in the abrupt slope zones. The Lunpola basin may have diversified favorable exploration targets,indicative of a good exploration prospect.
出处
《地质与勘探》
CAS
CSCD
北大核心
2015年第4期789-796,共8页
Geology and Exploration
基金
国土资源部油气中心项目下设专题(编号:1211302108021-1)资助
关键词
断拗盆地
构造-沉积模式
沉积体系组合
隐蔽性油藏
古近系
伦坡拉盆地
西藏
fault-depression basin
structure-sedimentary model
integrated pattern of sedimentary system
subtle reservoir
Paleogene
Lunpola basin
Tibet
