未出现径向流的试井典型曲线及其分析方法

Typical curves and their analysis method for well test data without radial flow response

低渗透、特低渗透油气藏经过长时间测试后会仍然不出现径向流响应,采用常规Gringarten-Bourdet复合图版难以有效地确定出地层参数。通过均质无限大试井模型短时渐近解,求解出无因次井筒储集系数和表皮因子复合参数与无因次时间、无因次井底压力的关系式(ζ函数)。利用无因次压力和ζ函数构造出新的早期试井解释图版,该图版能够降低早期试井数据分析的多解性。通过建立均质油藏达西流模型及考虑启动压力梯度的均质油藏非达西流模型,给出了这2种模型对应的早期新图版,并分析了新图版的典型特征和渐近性质。与已有的早期试井分析图版对比发现,新图版对均质模型及考虑启动压力梯度的均质模型参数变化响应更加敏感,能够更有效地降低早期试井解释的多解性。

The radial flow response does not exhibit after a long time testing for the low and ultra-low permeability reservoirs.In this case,it is difficult to determine the formation parameters effectively by using the conventional Gringarten-Bourdet's typical curve method.Based on a short-time asymptotic solution of homogeneous infinite well testing model,the relation between the dimensionless time and bottom pressure and the combination parameters of dimensionless wellbore storage coefficient and skin factor(ζfunction)was obtained.A new type of early-time transient well testing interpretation type curve was constructed by using the dimensionless bottom pressure andζfunction,which can reduce the non unique solution problem of early-time transient well testing data analysis.The homogeneous Darcy flow model and homogeneous non-Darcy flow model considering the threshold pressure gradient were established to construct the new type curves.The characteristics and asymptotics of the above two kinds of type curves were also discussed.The results showed that compared with the conventional type curves the two new kinds of type curves were more sensitive to the parameter changes in homogenous model,which would effectively reduce the non unique solution problem of the well testing interpretation.