基于微观驱替实验的剩余油表征方法研究

Research on characterization method for residual oil based on microscopic displacement experiments

为了弄清楚水驱油藏微观剩余油的形成和分布机理及剩余油挖潜的方向,采用毛细管模型研究了微观剩余油形成机理;利用玻璃刻蚀模型进行了室内水驱实验,研究了微观水驱渗流机理。结果表明,在驱替初期,原油沿着微观模型主对角线流动,当形成有利渗流通道时,驱替液将通过有利孔道流向出口端导致驱替效率降低。根据微观水驱剩余油特征建立了剩余油微观判识定量分类标准,将剩余油分为滴状、柱状、油膜型、分枝状和连片型五种类型。定量分析了水驱结束后不同类型剩余油的比例,分枝状剩余油的比例远远超过了其他几种剩余油的比例,这为进一步进行剩余油挖潜工作提供指导。

In order to study the formation and distribution characteristics of residual oil, and to understand the direction ot residual oil development, capillary model and glass etching model were used to study formation mechanism of residual oil and percolation mechanism of water displacing,respectively. The experimental results show that the displacement fluids flow along the main diagonal of microscopic model at the beginning of water flooding, displacement fluid will flow through favorable channels to the outlet when favorable seepage channels formed, which results in the decreasing of displacement efficiency. A microscopic quantitative classification criterion of residual oil is established, and the residual oil is classified into droplet type, columnar type, oil film type, branched type and contiguous type. The proportions of the five types residual oil after flooding are obtained by statistic approach, the ratio of branched type residual oil is far more than that of the other types residual oil, and this result may provide guidance for further development of residual oil.