注水开发对储层砂岩粒度分布的影响

通过对中国东部某油田老第三系沙河街组第三段中亚段砂岩储层注水开发前后粒度分布特征的对照研究 ,以及研究区块内由生产井带出沉积物粒度分布特征的对照研究 ,认为注水开发过程造成了储层砂岩极细砂粒级沉积物的丢失。由于这些极细砂的主要赋存状态是粗砂、以及砾级碎屑颗粒间的充填物 ,因而极细砂沉积物丢失可造成岩石物性和孔隙结构的一系列变化 ,尤其是渗透率的大幅度提高。同时也说明注入水的压差、流速、流体粘度和流动方式等物理学特征 ,以及储层本身的孔隙大小、孔隙度和渗透率等特征 ,在很大程度上是与极细砂级沉积物的搬运条件相适应的

EFFECT OF WATERFLOODING ON GRAIN SIZE DISTRIBUTION OF SANDSTONE RESERVOIR

With an oilfield example from the middle part of Member 3, Shahejie Formation, Lower Tertiary in the east part of China. This paper discusses the change of sediment grain size distribution of reservoir sandstone after waterflooding. By means of the comparison of earlier exploration wells and examined wells after developed by waterflooding about 10 years, the authors find that very fine sand sediments were lost by the waterflooding. Because the very fine sands are often filled in the inter granular pores, their losing should result in the change of pore structure parameters, such as diameter and sorting of pore throat and mercury withdrawal efficiency, and permeability. This study also shows that the pressure difference, velocity, fluid viscidity and current mode of the waterflooding, and porosity and permeability are adapted for the transporting conditions of very fine size sands.