Abstract: Assuming formation dipping angle,permeability and porosity are constants,homogeneous and isotropy formation.Fluid is incompressible,and straigt initial gas-water boundary line in edge water gas reservoir,the stable condition for boundary line movement is strictly proved by using method of small perturbation in fluid dynamics.The problem is first converted to plane problem,the velocity potential function is introduced,the real velocity of fluid mass point on boundary line is converted to vadose velocity according to Lagrange view,the dynamic condition to which the potential function on boundary line is put out,which concluded the problem to the solution of Laplace equation.According to the assumption of straight initial boundry line,the problem is then linearized,the solution for the problem of straight boundary line is obtained.Furthmore,after introducing perturbing quantity and perturbing potential function,the problem is then concluded to the solution of Laplace equation and dynamic condition to which the perturbing potential function and perturbing quantity suit.The solution for perturbing quatity and perturbing potential function is easy to obtain because the problem is linear homogeneous.Stable condition for movement can be obtained from solution expressinon.Final result is substantially in conformance with referencel.

Key words: edge water gas reservoir, gas-water boundary face, stability of movement, potential function perturbation

摘要： 在地层倾角、渗透率、孔隙度为常数、地层均质各向同性,流体不可压缩,边水气藏初始气水分界线平直的假设条件下,用流体动力学小扰动方法,严格证得了分界线运动的稳定性条件.首先将问题转化为平面问题,然后引进速度势函数,据Lagrange观点,将分界线上流体质点的真实速度转换为渗流速度,并写出分界线上势函数应满足的动力学条件,将问题归结为Laplace方程的求解.据初始分界线平直的假定,又将问题线性化,从而求得平直分界线问题的解.进一步引进扰动量和扰动势函数后,又将问题归结为求解扰动势函数和扰动量所满足的Laplace方程和动力学条件.由于问题是齐次线性的,容易求得扰动势函数和扰动量的解.从解的表达式,便可得到运动的稳定性条件.最后结果与文献1的结果实质上是一致的.

关键词: 边水气藏, 气水分界面, 运动稳定性, 势函数, 扰动