双重介质油藏注水井试井解释模型的建立及应用

Establishment and application of a well test interpretation model for injection wells in dual porosity reservoir

针对双重介质油藏注水开发特征,基于Buckley-Leverett饱和度分布方程建立了注水井压降试井解释模型,通过Laplace变换和Stehfest数值反演对模型进行了求解,利用无因次压力降落解获得了注水井的压力降落典型图版。分析图版可知,两相区对注水井压力响应特征较大,油水黏度差异会导致双对数压力导数曲线上翘,并且两者差异越大,两相区双对数压力导数曲线上翘幅度越大,因此在试井解释时应区别储层物性变化或不渗透边界造成的压力导数曲线上翘。选取JZ油田1口注水井进行了实例应用,结果表明本文解释图版拟合结果与现场测试数据吻合较好,并且解释所得的储层参数合理。本文建立的试井解释模型可以计算注水前缘的位置,分析注水井周围地层信息及边界情况,对评价双重介质油藏注水井的动态及注水方案的设计具有重要的指导意义。

Based on water flooding characteristics of dual porosity reservoir and Buckley-Leverett equation, the injection pressure drop testing interpretation model is established. Laplace transform and Stehfest numerical inversion are used to solve the model and a pressure drop typical plate of injection well is obtained with dimensionless pressure drop solution. Results show that oil-water two-phase region has large pressure response characteristics, oil-water viscosity difference causes double logarithmic curve upward. The larger the difference of oil-water viscosity, the more two-phase double logarithmic curve upturns. So the upward curve caused by reservoir change or impermeability boundary should be distinguished. The application in an injection well of JZ oilfield shows that the interpretation results agree with field test data. The proposed model can be used to calculate the position of water flood front, and to analyze the formation around the injection well and boundary condition, thus guiding water injection well evaluation and the design of injection scheme.