不稳态依序替换法确定气井波及半径和渗透率——以川东沙坪场气田为例

Calculating Swept Radius and Affective Permeability of Gas Well by Rule of Unsteady State Ordinal Replacement——A Case Study of the Gas Field in Chuandong Shapingchang

地层的有效渗透率和波及半径的确定对气井生产有着重要的作用。根据气井不稳态渗流模型的解,将气井渗流区域分为激动区和未激动区。在压力波及到边界之前,根据激动区半径的定义,得出生产时间的二分之一次方与激动区半径呈直线关系。压力波及到边界之后,激动区半径出现转折,以此确定波及半径到达边界的时间。结合到达边界的时间与圆形封闭不稳态渗流模型的解确定气井井控范围内地层的有效渗透率。根据压力波及到边界的时间和地层的有效渗透率进一步确定单井井控半径。根据川东沙坪场气田生产动态资料计算得出的结果与试井解释的结果基本一致。

The determination of effective permeability and the swept radius of stratum plays an important role in gas well production. According to the solution of the unsteady flow model, the influent area of the gas well was divided into fluctuating and unfluctuating area. Combined with the definition of the swept radius, there was a linear relationship between 1/2 power of the production time and the swept radius before the pressure wave reaching to the boundary. The radius of the fluctuating area appeared to turn after the pressure wave reaching to the boundary, which determined the time of which the pressure wave reached to the boundary. The effective permeability of the stratum in the well control range of the gas well was determined by the time of reaching to boundary and the solution of the circular closed unsteady seepage flow model. The control radius of the well was further determined according to the time of the pressure wave to the boundary and the effective permeability of the formation. The calculated results of production dynamic data calculated in the gas field of Chuandong Shapingchang were basically consistent with the results of well test interpretation.