考虑滑脱效应的低渗透气藏试井分析方法

本文在考虑低渗透气藏气体渗流的滑脱效应下,建立了低渗透气藏气体渗流数学模型。找到了一种可以使该数学模型及其定解条件线性化的拟压力函数和拟时间函数。使用这种新的拟压力函数和拟时间函数时,低渗透气藏的渗流数学模型变成具有常规油藏渗流数学模型一样的形式,因此,当采用本文定义的拟压力函数和拟时间函数时,可以借助于成熟的油井试井理论来解释低渗透气藏气井试井数据。文中还探讨了由低渗透气藏气井试井数据计算相应的拟压力函数位和拟时间函数值的方法,探讨了滑脱系数对计算拟压力函数值拟时间函数值的影响等。通过矿场实例分析表明,本文方法效果较好,这为解释低渗透气井试井数据找到了一种行之有效的方法。

ANALYTICAL METHOD OF WELL TEST IN LOW-PERMEABILITY GAS RESERVOIR CONSIDERING EFFECT OF GAS SLIPPAGE

Considering the effect of gas slippage, this paper presents a mathematical model of gas flow through low-permeability gas reservoir and finds pseudopressure and pseudotime functions which make the mathematical model and de finite solution condition linearized When the new pseudopressure and pseudotime are used, the model of gas flow through lowpermeabilitygas reservoir becomes the same form as the conventional mathematical model of reservoir permeability. Therefore, when the pseudopressure and pseudotime functions defined in this paper are used, the mature theory of well test analysis may be useed to explain the well test data of low-permeabi lity gas reservoir. The method of calculating corresponding pseudopressure and pseudotime values from well test data in low-permeability gas reservoir is discussed in the paper. The effect of gas slippage on calculating pseudobressure and pseudotime values is also discussed. It is shown from field examples that the results obtained are satisfactory and the new method is proved to be an effective one for analyzing well test data in low-permeability gas reservoir.