海相改造残留盆地的地质特征和勘探前景

GEOLOGICAL CHARACTERS AND EXPLORATION PROSPECTS OF REFORMED-RESIDUAL BASINS

中国前新生界海相地层很发育 ,其油气资源潜量丰富 ,但目前探明程度和勘探成功率很低。其根本原因在于它们普遍经历过多期改造 ,具有改造残留盆地的性质。主要的改造方式有抬升剥蚀、构造变形和深埋等 ,具体受盆地在各期构造运动中所处的大地构造背景控制 ,如被前陆盆地或裂谷盆地所叠加 ,整体抬升转化成为高原或高地 ,以及由于冲断褶皱而转化为断褶带甚至于造山带等。海相改造残留盆地具有复杂的成藏动力学过程和油气系统。其最重要的油气成藏特点有 :( 1 )多期成藏 ,形成复杂油气系统 ,油气藏高度分散 ;( 2 )晚期 (喜马拉雅期 )成藏 ,明显受喜马拉雅运动控制。因此在油气勘探中要以正确认识和描述地质特征的非均一性为关键 ,以油气的生、运、散、聚成藏动力学过程为主线 ,从各种地质要素的相互作用的发展演化历史的角度开展研究。海相改造残留盆地勘探前景广阔 ,必将成为我国 2 1世纪油气勘探的主战场。

Pre-Cenozoic marine strata widely developed in China.These strata have rich potential hydrocarbon reserves but their exploration degree and success ratio are low since they underwent multi-stage reformation and have the feature of residul basin.The reformation includes erosion,structural deformation and deep burial etc.However,the ways of reformation,such as being superposed by foreland basin or rift basin,being uplifted as a plateau or highland,being transformed from thrust folds into fault-fold belt or even orogenic zone,etc.Marine residual basins have complex hydrocarbon pool-forming dynamics.The most important hydrocarbon pool-forming properties are:(1)multi-stage hydrocarbon accumulation resulted in the formation of complex oil and gas systems with dispersed oil and gas pools;(2)late-stage pool-forming controlled by Himalayan movement.Therefor,the key problem of petroleum exploration in residual basins is to understand and describe their heterogeneity of geological characters,graps the dynamic process of hydrocarbon generation,migration,dispersion and accumulation,study the evolution history of various geological factors.In short,marine reformed residual basins bear bright prospects in oil and gas exploration,amd they bound to be the main targets of China's oil and gas exploration in the 21st century.