高含水期油藏特有水驱渗流规律研究

Peculiar water-flooding law during high water-cut stage in oilfield

我国绝大多数油田已进入高含水期,高含水期油藏表现出特有的水驱渗流规律,即水驱曲线后期存在上翘现象,同时室内试验同样观察到含水率较高时lnkro/krw与Sw关系曲线存在下弯现象。针对上述特有水驱渗流规律,经过大量的数据统计和曲线分析,提出一种新的渗流特征方程,并以此为基础,理论推导出新型水驱特征曲线方程,并指出常用水驱曲线是新型水驱曲线的一种简化。研究认为lnkro/krw与Sw关系曲线在高含水期存在下弯现象的根本原因是随含水饱和度的进一步增加,油相由大片的连续相变为部分连续,再进一步变为非连续相,使得油相渗流能力骤减,导致lnkro/krw与Sw关系曲线出现下弯,而这也恰是水驱曲线在高含水期上翘的根本原因,其内在的本质规律是统一的。

Recently,most of the oilfields are during the high water cut stage in our country.It demonstrates some special characteristics,such as water-flooding characteristic curves shows up-warping phenomenon,and the relationship curve shows bend-down phenomenon.Through a lot of statistics and curves analysis,a new flow characteristic equation was proposed.Based on the above mentioned,the new water-flooding characteristic curve was derived.The basic reason of the special phenomenon is that the continual oil phase change into the discontinuous phase which leads to the seepage capability of oil phase decrease sharply.These indicate that essential law of up-warping and bend down phenomenon is unified.