考虑反凝析影响的凝析气井产能试井问题

大量的理论分析和现场应用表明,反凝析液析出会急剧降低近井区气相相对渗透率,从而使凝析气井流入动态发生较大改变。而在产能试井中很容易出现井底流压低于露点压力的情况,因此反凝析现象不可避免。目前的产能试井工艺很少关注反凝析现象对气井流入动态的影响,结果常造成二项式指示曲线斜率为负,所建立的产能方程也不能有效地用于生产动态分析。在充分考虑反凝析影响的基础上,详细分析了工作制度变化对渗透率的影响,论证了工作制度的合理选择对于产能分析的重要性。首次提出利用拟稳态形式产能方程系数与井底流压的关系曲线可以便捷和正确分析凝析气井流入动态。实例分析证明,利用提出的方法,能正确建立流入动态方程。

Productivity Well Test for Gas Condensate Well Considering Retrograde Condensate Effect

Numerous theoretical analyses and field applications indicate that relative permeability to gas near wellbore area declines rapidly due to precipitation of retrograde condensate fluid, which will result in great changes of inflow performance of gas condensate wells. The retrograde condensation impact tends to be unavoidable because the phenomenon that bottomhole producing pressure is lower than dew point pressure is easy to be found in productivity well test. However, the impact is seldom considered in present productivity well test technology. Consequently, the slope of indication curve often shows negative and the productivity equation is unable to be effectively applied for production performance analysis. In view of this issue, this paper analyzes the effect of choke size change on permeability in detail, demonstrate that the reasonable selection of choke size is of great significance to productivity analysis, and firstly proposes that the usage of curves between coefficient from pseudosteady-state productivity equation and bottomhole producing pressure is convenient to analyze the inflow performance of gas condensate wells correctly. Case study proves that the proposed method is contributed to properly establish the inflow performance relationship (IPR) for gas condensate wells.