压力积分函数在不稳定试井分析中的应用

Application of pressure integral functions in transient well test analysis

实测试井数据常常由于噪音的存在而严重影响试井曲线的拟合精度,通过引入压力积分函数的概念,提出了一种减少数据噪音、提高数据拟合精度的新方法。在考虑井筒储集效应及表皮效应的情况下,通过求解无限大均质油藏中的无量纲压力积分函数,绘制了压力积分、压力导数积分及压力积分比值典型曲线新图版,并对曲线特征进行了描述;推导得出了应用压力积分函数进行常规半对数分析和典型曲线拟合的方法。在此基础上进行实例分析,结果表明,压力积分函数应用于不稳定试井分析,可有效减少噪音影响,简化拟合过程,提高拟合精度,结果可靠。

Well test data are often ambiguous due to the existence of data noise and it seriously affect the accuracy of typical curve matching. By means of the introduction of pressure integral functions, we present a new method which can reduce data noise and can improve the accuracy of well test data matching. With the considering of the effect of wellbore storage and skin factor, the dimensionless pressure integral solution is established in an infinite homogeneous reservoir. The corresponding type curve plates are drawn out based on pressure integral and pressure integral derivative functions as well as pressure integral ratio. We also demonstrate the characteristics of type curves. In addition, the method of conventional semi-log analysis and typical curve matching on well test data is derived using the pressure integral functions. Finally, a field example analysis is performed. It is shown that with the application of the new pressure functions, the noisy data becomes much smoother after being integrated, the matching process is simplified and the matching accuracy is improved.