关于开采底水油藏几个重要参数的确定

基于底水油藏具有两种渗流模型的假设，即射孔段上部为水平径向流动，射孔段下部为半球状向心流动，推导出油井见水前离井轴任一半径在任一时刻的水锥高度的隐式函数，由此可确定底水的突破时间和不同时刻水锥的剖面形态。在此基础上讨论了无水生产期的产油量与井距和射孔程度的关系，并求得了最佳射孔程度的数学表达式。通过对溪南庄油田及公开发表文献的实例分析计算，其见水时间预测误差均小于5％，说明提出的渗流模型及其解精确可靠，对底水油藏的开发和设计具有一定的参考和指导意义。

Determination of several important parameters for the producing of bottom water reservoir-water breakthrough time, oil production in water-free period, and optimum perforation degree

Based on the assumption that the bottom water reservoir has two kinds of percolation model, which is horizontal radial flow in the upper part of perforation interval, and hemispherical cen-tripetal flow in the lower part, this paper deduces the implicit func tion of water eoning height at any radius away from borehole axis at any time before water breakthrough in the oil well, and then the botlom water breakthrough time and the profile seetions of water co-ning at different time can be determined. Then the paper discusses the relationship between oil production in water-free period and well spaeing and peroration degree, and it gets the mathematics eeonom-ics of optimum peroration degree. Case analysis and ealeulation of Xinanzhuang oilfield and other published documents show that all prediction errors of water breakthrough time are lowered than 5% , which indicates that the proposed percolation models and their solu-tions are reliable and accurate, and can be served as reference in the producing and the designing of other bottom water reservoirs.