陆相层序地层学进展与在油气勘探开发中的应用

Progress in continental sequence stratigraphy and its application in petroleum exploration and development

陆相层序地层与被动大陆边缘海相层序地层之间存在较大的差异。陆相盆地沉积受多种因素控制 ,而且不同类型盆地的主要控制因素又各不相同 ,造就了陆相盆地沉积类型多、相变快、横向连续性差、纵向上层序厚度变化大 ,频繁的湖侵湖退使湖盆沉积垂向上韵律变化快 ;因此陆相层序地层的形成、结构和模式更为复杂 ,研究更为困难。在研究与实践中 ,中国学者根据陆相盆地的边界特征、体系域边界特征、初始湖泛面和最大湖泛面、是否有坡折带等因素 ,建立了符合中国盆地沉积实际的坳陷型盆地和断陷型盆地层序地层格架和模式。控制陆相地层层序发育的因素主要是湖平面的变化、构造、气候、基准面的变化和物源的供给 ,特别是构造和气候显得十分重要 ,它们直接控制了湖平面的变化。陆相地层层序研究的方法体系主要包括露头层序研究方法、实验观测和分析方法、测井层序地层分析、地震层序地层分析和层序地层的数值模拟方法。在油气勘探中的区带勘探阶段、目标勘探阶段和开发阶段 ,层序地层学都能发挥不可替代的作用。

Sedimentation in continental basins has been controlled by many factors and the main control factors in basins of different types are not the same.All these would lead to various sedimentation types,frequent facies changes,poor lateral continuity and large variation of sequence thickness.Frequent alternating of lake transgression and regression results in frequent change of cyclothems.The formation,structure and model of continental sequence stratigraphy would,therefore,be more complex and more difficult to study.According to the boundary characteristics of both continental basins and system tracts,initial and maximum flooding surfaces and existence of slope-break zone,Chinese geologists have established sequence stratigraphic frameworks and models of depression basin and faulted basin,which tally with the reality of basin fills in China.Development of continental stratigraphic sequence has mainly been controlled by lake level fluctuation,tectonic movement,climate,base-level change and provenance supply,especially tectonic movement and climate are quite important,because they directly control the fluctuation of lake level.Methodologies for studying sequence stratigraphy in continental basins include outcrop sequence study,experimental observation and analysis,logging and seismic sequence stratigraphic analyses,and numerical simulation of sequence stratigraphy.Sequence stratigraphy can play an irreplaceable role in play exploration stage,prospect exploration stage and development stage.