Abstract:

There exist differences in the pressure propagation law of the low-velocity non-Darcy flow and Darcy flow due to the presence of a starting pressure gradient. The present paper established a model of the non-Darcy flow under conditions of both the fixed bottom-hole pressure and the fixed flow capacity by using a method of steady-state successive approach to unsteady-state solution, and examined pressure-propagation characteristics of the low-velocity non-Darcy flow under the above-mentioned conditions. The study defined a pressure-conductivity retardation coefficient, which was used to representing the effect of the starting pressure gradient on the speed of pressure propagation, namely the greater the coefficient, the longer the time required for the pressure propagation within a given distance. The speed of pressure propagation, however, could be accelerated by increasing liquid yield. Different from the Darcy flow, low permeability reservoirs have a limiting radius, to which once the distance of pressure propagation reaches, pressure is no longer propagating.

Key words: non-Darcy flow, pressure distribution, pressure-conductivity retardation coefficient, starting pressure gradient, low permeability reservoir

摘要：

由于启动压力梯度存在，低速非达西渗流与达西渗流在压力传播规律等方面存在不同。运用稳态逐次逼近非稳态解的方法，建立了定流量和定流压条件下的非达西渗流模型，研究了两种情况下低速非达西渗流中的压力传播特征。定义了导压阻滞系数，导压阻滞系数,用于表征启动压力梯度对压力传播速度的影响。导压阻滞系数越大，压力传播到某一给定范围所需时间越长，但产液量的增加可使压力传播速度加快。不同于达西渗流，低渗透储层存在一个极限半径，当压力传播半径达到该值后，不再向外传播。

关键词: 非达西渗流, 压力分布, 导压阻滞系数, 启动压力梯度, 低渗透储层