深层致密气藏扩展指数递减模型及其在新场须五气藏的应用

研究扩展指数(SEPD)递减模型的性质与参数求取方法,探索深层致密气藏的递减分析方法。通过理论推导与新场须五气藏开发实践的综合分析,结果表明SEPD递减模型具有"双三一相关"以及"有界性"特征,并针对新场须五气藏提出了"多点采样梯度下降法"求取模型参数的方法。实践表明,新场须五深层致密气藏递减特征与SEPD递减模型的递减特征一致,采用"多点采样梯度下降法"可有效地求取模型参数,进而为开展深层致密气藏产量预测与储量评价提供保障。

Application of stretched exponential production decline model to the Xu-5 deep tight gas reservoir of Xinchang,Sichuan, China

The property of stretched exponential production decline model (SEPD) is studied and the way of seeking the parameter for SEPD is exercised in order to explore production decline analysis for deep tight gas reservoir.Theoretical derivation and comprehensive analysis for the Xu-5 reservoir reveal that the SEPD is characterized by "three parameters","one correlation" and "boundedness",and accordingly,a method of multiple position sampling and gradient descent is proposed to obtain parameters for the model.The application of SEPD to the Xu-5 (Member 5 of Upper Triassic Xujiahe Formation) gas reservoir in Xinchang area indicates that production decline characteristics of Xu-5 are in accordance with SEPD,and the multiple position sampling and gradient descent method can effectively obtain the model parameters.Therefore,this method is important in the prediction and evaluation of production of gas field.