考虑油相启动压力梯度的蒸汽前缘数学模型

稠油热采过程中,蒸汽前缘的移动规律一直受到人们的重视。稠油地下渗流具有非牛顿特征,多数研究者考虑了蒸汽超覆和拟流度比对蒸汽前缘的影响;但是未考虑稠油的启动压力梯度。针对稠油非牛顿特征,通过对蒸汽前缘上边界进行表征,建立了同时考虑启动压力梯度、蒸汽前缘上边界变化和拟流度比的蒸汽前缘数学模型,弥补了现行蒸汽前缘数学模型的一个缺陷。通过进行差分离散及Matlab数值计算,得到了形状因子、拟流度比与蒸汽前缘形状关系图版。结果表明,蒸汽前缘上边界随着启动压力梯度的增大而减小,增大形状因子或减小拟流度比,均可降低蒸汽超覆程度,提高蒸汽前缘的波及效率。

A mathematical model for steam flooding frontier considering oil threshold pressure gradient

Great emphasis has been placed on steam flooding frontier. Most researches consider the steam overlap and pseudo mobility ratio. But heavy oil is non-Newton fluid, oil threshold pressure gradient is not taken into account. In order to study the steam flooding frontier of non-Newtonian heavy oil, the dynamic point contact with the cap rock of steam flooding frontier is present first. And then a mathematical model for steam flooding frontier considering oil threshold pressure gradient is established. The steam zone is obtained by difference and programming with Matlab. The results show that the greater the threshold pressure gradient, the smaller the dynamic contact point. And increasing the shape factor or decreasing the pseudo mobility ratio can reduce steam override degree and increase steam sweep efficiency.