一个新的凝析气井试井解释模型及其应用

NEW MODEL OF WELL TEST INTERPRETATION AND ITS APPLICATION FOR CONDENSATE GAS WELLS

在凝析气的渗流过程中,当井底压力低于体系的露点压力时,凝析油、气共存而凝析油不流动区域的流度和储存系数随径向距离的变化可以用幂律形式来描述。文章基于气体单相渗流理论,建立和求解了过渡区流度和储存系数呈幂律变化的三区径向复合油藏试井解释新模型,利用Stehfest反演算法计算了井底压力响应典型曲线,分析了流度和储存系数变化指数对井底压力动态的影响。通过理论图版拟合和试井曲线的模拟检验,可以获得流度和储存系数变化指数,确定过渡区的流度和储存系数随径向距离的变化关系。实例计算表明,该模型能够更好的反映凝析油在近井地带的析出和累积规律,可推广到注气井和热采井的试井分析中。

In the percolation process of condensate gas, when the bottom-hole flowing pressure drops down the dew-point pressure, the variation of the mobility and storntivity along with the radial distance can be described by power law in the zones where condensate oil and gas both exist, but the condensate oil can't flow, Based on the gas monophase percolation theory, a new model of well test interpretation is established and solved for three-zone radial composite reservoirs in the transitional areas where the mobility and storativity changes by power law. With the Stehfest numerical inversion method, the typical respond curves of bottom-hole pressure are calculated, and the influence of the various indexes of mobility and storativity on the performance of bottom-hole pressure is analyzed. With theoretical chart board fitting and well testing curves simulating, the changing indexes of mobility and storativity can be obtained, and the variation of mobility and storativily along with the radial distance can be determined in the transitional areas. Real cases calculating shows the model can reflect the separation and accumulation law of condensate oil in the zones near the borehole better. Also, the model can be applied for the well test analysis of gas injection wells and thermal recovery wells.