一种求解低速非达西渗流试井模型的新方法

实验表明：在一定的含水饱和度条件下，水作为润湿相占据了较多的细小喉道，使得气体的流动能力下降，渗流规律发生了变化，气体在低渗透气藏中渗流表现出启动压力特征。这时，气体的流动形态可分为2个区，即非线性区和线性区。通过将非线性区渗流时的指数式方程简化为达西渗流方程，建立了低渗透气藏考虑启动压力梯度的两段渗流数据模型，同时运用Laplace变换和Green函数方法求解了该模型的Laplace空间解，通过数值反演方法，作出了理论图版，并讨论了临界流速、临界压力梯度及启动压力梯度对低渗透气藏压降动态的影响。

A New Method to Solve Well Test Model of Non-Darcy Flow at A Low Speed

Experiment studies showed that:under certain water saturation,water by way of wetting phase takes up much exiguous throat,which makes the flow capacity of gas fell and the percolation law changed.Gas flow at low permeability gas reservoir is characteristic of starting pressure.Here,the flow form divides to two region:namely nonlinear region and linear region.By simplifying the non linear flow function as Darcy flow function,a two stage percolation mathematical model considering starting pressure gradient was established.By using Laplace transformation and Green function method,The Laplace solution was obtained.With numerical inversion,theoretical type curve was gotten.And the influence of critical flow speed,critical pressure gradient and starting pressure gradient was also discussed in the paper.