断陷湖盆地震相模式研究要点——以Capella油田为例

Key research points on seismic facies models of faulted lake basin:a case study of Capella Oilfield

Capella地区整体表现为一"东断西超"狭长型断陷湖盆,具有缓坡带发育多种沉积相带类型、地震反射特征复杂多变以及湖盆短轴方向存在距离短、多源碎屑物叠置区分难度大的特点。传统断陷湖盆地震相模式在Capella湖盆陡坡区和长轴入口区的沉积相研究中具有较好的应用效果,但在缓坡区和湖心区识别不同相带沉积物时存在一定的困难。文章对研究区断陷湖盆自身发育特点和地震相模式建立的难点进行了详细剖析并提出针对不同问题的解决方法。在断陷湖盆不同地带沉积体系研究的基础上,明确了不同相带地震相特征和彼此间的差异,最终建立了一套适用于狭长型断陷湖盆的地震相模式,为后人对此类断陷盆地沉积相解释、评价以及储层预测提供了一定的理论基础。

Capella Oilfield faulted in east and overlapped in west,is a narrow rift lacustrine basin.On the one hand,this basin is characterized by a variety types of deposition facies on its gentle slope belt and seismic reflection characteristics are complex.On the other hand,multi-source clastic material are difficult to be identified since the short axis of the basin is short and the multi-source clastic material deposit from different direction and overlap in the lake center.Conventional seismic facies models of faulted depression basin can achieve good results in the steep slope zone and in the long axis of the entrance area of Capella area,while they have difficulties in identifying deposits of different sedimentary facies in the gentle slope area and in the lake center.In this article,we show a detailed analysis on the developmental characteristics of Capella faulted depression basin,and put forward solutions to the difficulties of seismic facies model building.On the basis of studies on sedimentary system of Capella faulted depression basin,we have found out seismic facies characteristics of different deposits,and finally established a set of seismic facies models of narrow faulted depression basin,which provide a theoretical basis for interpretation and evaluation on sedimentary facies and reservoir prediction in this type of basins.