松辽盆地北部浅水三角洲前缘砂体类型、特征与沉积动力学过程分析

通过充分利用开发检查全井段的取芯资料,结合开发井的水动力资料,系统总结出地形、河流与湖泊大小、气候变化和湖面升降对浅水三角洲前缘沉积环境的影响,分析了浅水三角洲的沉积动力学过程.浅水三角洲前缘平坦、开阔.三角洲平原上的分流河道向湖泊中心方向长距离推进,在三角洲前缘的浅水区发育很有特色的水下分流河道,且在湖面频繁波动过程中,河流、波浪和沿岸流的冲刷作用对沉积物的分布起到重要作用,导致以水下分流河道砂体为主的三角洲前缘砂体不同程度的席状化.随着气候变得潮湿,湖面相对稳定,季节性、周期性湖面波动的频率、幅度也减小,水动力对三角洲前缘砂体的改造和席状化强度减弱.

Types, characteristics of sandbodies in shallow-water deltafront and sedimentary models in Northern Songliao Basin, China

On the basis of core information from development inspection wells and combining hydrodynamic information from the developing wells, it could be possible to systematically summarize the influence of configuration and size of rivers and lakes, climate changes and lake level fluctuation on the sandbodies at the shallow-water lake delta front and analyze their sedimentary dynamic process.Studied area locates at Sourthern Daqing oil field. There are many developing wells and materials, which can be used to analyze the sedimentary environments and microfacies. Shallow-water delta front is flat and widen. The channel on the delta plain advanced toward the center of the lake over a long distance develope and distinctive underwater distributary channels. Accompanying the frequent fluctuation of lake level , the hydrodynamics of rivers, waves and longshore currents reworked the sediments on the delta front, which induced sheetlization of delta-front sandbodies dominated by subaqueous channel sandbodies. As the climate becomes humid and the lake level becomes relatively stable, the frequency and range of the seasonal and periodic fluctuation of lake level decreases. All these makes that both the hydrodynamics reworking of the delta front sandbodies and the strength of sheetlization become weak.