最优化方法在低渗透气藏试井分析中的应用

APPLICATION OF OPTIMIZATION METHOD IN WELL TEST ANALYSIS OF LOW PERMEABILITY GAS RESERVOIR

不管是理论上还是在实践中都已经证明,低渗透气藏气井试井曲线的半对数关系为向上翘的“凹”型曲线,而且导致低渗透气藏试井曲线异常的原因主要是井筒续流效应和表皮效应的存在,以及气藏渗透率极低等因素。由于该类试井曲线异常,现有的常规试井解释方法和现代试井分析方法对此都无法处理,为此,本文提出采用最优化方法与数值模拟相结合来解释这类试井曲线,并通过多口实测井资料的分析表明,其方法是可行的。

It has been identified both theoretically and practically that semilog relationship of well test curves in low permeability gas reservoir is characteristic of bending upward with a concave shape and that causes resulting in anomaly of well test curves in low permeability gas reservoir are effect of wellbore afterflow and existence of skin effect as well as extremely low reservoir permeability. Present methods of conventional well test interpretation and modern well testing analysis are all not applicable in this case due to the anomaly of the well test curves. This paper suggests a method of combining optimisation method and anumerical simulation to interpret this type of curves. The analysis of data from many field measured wells shows that this method is feasible.