八面河地区孔店组河流-冲积相层序地层学研究

Study on the sequence stratigraphy of the fluvial-alluvial facies of Kongdian formation in Bamianhe area,Dongying Sag

从可容空间变化的角度分析了八面河地区孔店组层序地层特征,将该地区孔店组划分为3个四级层序,每个层序包括2个体系域.受气候和沉积物供给的控制,层序发育早期,可容空间较小,沉积物供给不足,河道不发育,只发育少量冲积扇和大面积泛滥平原的红色泥岩、粉砂质泥岩.层序发育后期,可容空间达到最大,干旱背景下气候相对湿润,沉积物快速供给并形成层序发育的主要控制因素,河道发育并频繁摆动形成河道砂体在纵向上的叠置和平面上的广泛分布.这种沉积物和气候控制的层序,其界面除可以用常规方法识别外,在该地区还表现为地震反射内部结构的差异和声波-深度坐标中声波时差回归曲线的非一致性.

Fluvail-alluvail facies is one of the most important reservoir types.The uniform sequence stratigraphy modes of fluvial-alluvial facies are not concluded because of its variety and lack of transgressive condensed section or coal bed.According to the analyses of the allucial-fluvial facies deposit and the variation of accommodation space,Kongdian formation in this area is divided into three fourth-order sequences,two system tracts are included in each sequence.The development of the sequences is dominated by climate and sediment supply.In the early development stage of the sequences,the accommodation space is little but increases,and because of the lack of the sediment supply,only a little of red mud and silty mud of some alluvial fan and a large amount of flood plain deposit here and channel is not developed.In the late development stage,the climate is wetter,the accommodation space is up to the largest,and the quick sediment supply becomes the dominated factor of the development of the sequences.Because the frequent transferring of the developed channel,channel sandbody becomes the main sediment type of this system tracts.The sequences dominated by deposit and climate can be recognized not only by conventional methods but also by the difference in the internal structure of seismic reflection and the inconsistency of acoustic transit time regression curve