小断块边水油藏一般具有油藏规模小、含油带窄的特点。如果前期地质认识不清，没有对水体大小进行比较准确的预测与评价，而采取某些可能不合理的开发模式，将会降低整个油藏的开发效果。根据大港油田西58-8 小断块边水油藏地质及生产特征，通过补加虚拟含油区域建立了半圆形非定态水侵模型，应用物质平衡方程计算了水体体积，同时还采用油藏数值模拟方法对该区边水能量进行了评价。2 种方法计算结果基本一致，表明所建模型比较准确，计算水体体积比较合理。

The small fault block edge water reservoirs are characterized by small volume, narrow oil bearing area. In early development stage，if geological knowledge is not clear, the accurate evaluation of the size of edge water is not carried out, it will reduce development efficiency. Authors analyze the geology and production characteristic ofWest 58- 8 fault block reservoir, calculate the size of the water aquifer by use ofmaterial balance equation and evaluate the edge water energy by use of numerical simulation. The calculation results showthat twomethods （material balance equation and numerical simulation） are quite consistent. The model is accurate and reasonable.