东海盆地X凹陷油气成藏模式与勘探突破

Reservoir-forming models and exploration breakthroughs in X sag of East China Sea basin

基于东海盆地X凹陷新生代构造演化分析,剖析了构造演化对成藏组合时空展布的控制作用,开展了储盖组合、圈闭类型及油气差异富集研究,构建了X凹陷主要成藏模式。研究表明:①东海盆地X凹陷新生界划分为上部(柳浪组、玉泉组、龙井组)、中部(花港组)、下部(平湖组)成藏组合;②X凹陷具有4种主要成藏模式,即凹中背斜带南部有晚中新世断裂破坏的“局部”富集成藏模式、凹中背斜带北部无晚中新世断裂破坏的“整装”背斜成藏模式、凹中背斜带西部中—小背斜翼部岩性圈闭“断-砂”耦合成藏模式、西部斜坡带平湖组构造-岩性圈闭成藏模式;③凹中背斜带南部强挤压区上部和中部成藏组合“局部”富集背斜、凹中背斜带北部中强挤压区中部成藏组合“整装”背斜、凹中背斜带西部弱挤压区中部和下部成藏组合“断-砂”耦合背斜-岩性圈闭、西部斜坡带下部成藏组合构造-岩性圈闭是油气有利勘探方向。近年来,在以上认识指导下新发现了凹中背斜带南部N271气田、凹中背斜带西部H11S、X31气田等,西部斜坡带X137、X251E、X196S/E、TX63等油气田,勘探成效显著。

Based on the analysis of the Cenozoic tectonic evolution of X sag in the East China Sea basin,the control of the tectonic evolution on the spatiotemporal distribution of reservoir-forming assemblages was analyzed,and reservoir-cap assemblages,trap types,and differential hydrocarbon enrichment were studied to construct reservoir-forming models in X sag.Research shows that:①The Cenozoic of X sag in the East China Sea basin is divided into three reservoir-forming assemblages,including the upper(Liulang Formation,Yuquan Formation,Longjing Formation),middle(Huagang Formation),and lower(Pinghu Formation)reservoir-forming assemblages(plays);②Four main reservoir-forming models occured in X sag,i.e.,the“local”accumulation model with late Miocene fault destruction in the southern area of the central sag anticline belt,the“integrated”anticline accumulation model without late Miocene fault destruction in the northern area of the central sag anticline belt,the“fault-sand”coupling accumulation model of lithologic traps in the wings of medium to small anticlines in the western area of the central sag anticline belt,and the structural-lithologic trap accumulation model of the western slope belt in the Pinghu Formation;③The“local”enrichment of anticline in the upper and middle plays of the strong compression zone in the south of the central sag anticline belt,the“integrated”anticline in the middle plays of the strong compression zone in the north of the central sag anticline belt,anticline-lithologic traps with the“fault-sand”coupling in the middle and lower plays of the weak compression zone in the west of the central sag anticline belt,and the structural-lithologic traps in the lower plays of the western slope belt are favorable exploration directions of oil and gas.Under the guidance of the above understanding,exploration results are remarkable in recent years.The N271 gas field in the southern area of the central sag anticline belt,the H11S and X31 gas fields in the western area of the central sag anticline belt,the X137,X251E,X196S/E,TX63 and other oil and gas fields in the western slope have been discovered.