东营凹陷下第三系层序地层研究与隐蔽油气藏预测

Lower Tertiary Sequence Stratigraphy Study and the Forecast of Subtle Reservoir in Dongying Depression

应用层序地层学理论 ,利用地震、测井、岩心和分析化验资料 ,建立了东营凹陷下第三系层序界面识别标志 ,把东营凹陷下第三系划分为 1个超层序组 ,4个超层序 ,10个层序 ,进行体系域划分 ,建立了东营凹陷下第三系层序地层格架。构造坡折带是指由同沉积构造长期活动引起的沉积斜坡明显突变的地带 ,对盆地充填的可容纳空间和沉积作用可产生重要影响。通过层序地层格架与构造坡折带的研究 ,建立东营凹陷层序发育模式。受构造坡折带控制的层序低位域砂体和湖侵体系域砂体 ,成藏条件良好 ,最有利于形成隐蔽油气藏。

On the basis of comprehensive study of seismic data, well logging and other data, applying the sequence stratigraphy theory, one supersequence set, four supersequences and ten sequences are distinguished in Dongying depression. We identify system tracts for each sequence and build up isochronous sequence framework in Dongying depression. The structural slope break zone, resulting in the abrupt change of the depositional slope, is initiated by the long term activity of syndepositional structure. Structural slope break zone in the fault subsidence lacustrine basin constrained the change in the accommodation space of the basins, controlling the development of the depositional sequence and the distribution of the depositional system tracts and the sand bodies. By means of establishing lower Tertiary equence stratigraphic framework and sequence system tract model of Dongying depression, this paper puts forward that lowstand sand bodies controlled by structural slope break zones are favorable for forming subtle reservoirs.