页岩气井扩展指数递减模型研究

页岩气藏渗透率极低,用传统产量递减模型对页岩气井进行预测,结果过于乐观。为寻求适用于页岩气井的产能评价方法,以Arps递减分析方法为基础,对扩展指数递减模型展开研究。在模型应用过程中,将传统的递减曲线分析方法与概率预测框架相结合,根据单井初始递减率进行同类井的划分,在计算单井递减曲线参数的基础上,利用P指数概率准则求取具有代表性的井组递减曲线参数值,据此对单井进行概率性预测,从而规避了页岩气藏复杂性及上产措施对产量递减分析的影响,提高了页岩气藏产量动态预测的准确性。利用美国多口页岩气井的实际生产资料,进一步验证了该方法在页岩储层应用的准确性与可行性。

Stretched exponential decline model for shale gas well

The permeability of shale gas reservoir is very low. The prediction resuh with traditional production decline model is too optimistic for shale gas well. The stretched exponential decline model is developed to seek for an suitable method for productivity evaluation of shale gas well based on Arps production decline analysis method. In the process of model application, the traditional production decline analysis method is combined with probabilistic prediction model. Based on the parameters calculation of single well decline curve, the same kind wells are marked off according to initial decline ratio of single well. The representative parameter values of well group decline curve are determined with P index probability criterion. And then, the probability prediction for single well is made with these values. This method evades the influence of shale gas reservoir complexity and production increasing measurements on production decline analysis. The reliability of dynamic prediction on production is improved obviously. Case study is performed with practical production data of shale gas wells in USA. The accuracy and feasibility of this method used in shale gas reservoir is further verified.