页岩气藏生产井产量递减规律研究

Research on Production Decline Regularity of Production Wells in Shale Gas Reservoir

由于页岩气藏的特殊储层条件和渗流特征,页岩气井递减规律不同于常规天然气气井,其递减指数往往大于1,因此递减分析的常规方法 Arps已不适用。通过美国主要页岩气气田单井产量典型曲线,说明页岩气井产量递减规律的特殊性。分析对比各种产量递减方法的使用条件及优缺点,通过研究实际压裂页岩气井相应数据,优选出Blasingame、Fetkovich、AG、FMB、NPI这5种产量递减分析方法,并介绍它们的基本原理和适用条件。运用产量递减分析软件RTA建立页岩气生产井模型,输入相应页岩气藏参数,并采用这5种方法分别与实际生产和井底流压数据进行拟合,得出各自预测结果,并相互验证。结果表明,这5种方法计算结果相近,不仅提高了计算精度,且最大限度消除了人为误差。最后利用试井分析结果验证各递减分析方法得到的页岩气井井控半径,结果表明这5种递减方法均能适用于页岩气井产量预测。

Due to particular reservoir conditions and seepage characteristics, decreasing curve of shale gas well is different from that of conventional gas reservoirs and the conventional method Arps used for analyzing the production decline is no longer applicable as its actual decline index is always more than 1. Analyzed are typical production curves of single wells in main shale gas fields in America and described is the particularity of the production decline law. Compared are advantages and disadvantages of various production decline law analysis methods, analyzed are actual data obtained from shale gas well fracturing, selected are such 5 production decline law analysis methods as Blasingame, Fetkovich, AG, FMB and NPI and introduced are basic principles and application conditions of these methods. Adopted is the production decline analysis software RTA to establish shale gas well fracturing model, entered are relative shale gas reservoir parameters and used are these methods to fit respectively with actual production and bottom-hole flowing pressure data to get respective forecast results and check the results with each other. Results show that these methods are similar and combination of these methods can improve accuracy, reduce human errors as far as possible and predict shale gas well production effectively.