煤层气井井底流压计算方法

Methods of bottom-hole flow pressure calculations for coalbed methane wells

煤层气井的井底流压对于煤层气井的排采方案设计与管理具有重要的意义。借鉴常规气井井底流压的计算方法,结合煤层气井的排采方式和生产特点,采用不同的方法组合计算了煤层气井的井底流压,编制了煤层气井井底流压计算软件,并将计算结果与现场实测结果进行对比。利用现场煤层气排采数据分析了煤层气排采不同阶段井底流压与煤层气产量的关系。结果表明:对于纯气段压力的计算,平均温度-平均偏差系数法的计算值比Cullender-Smith法高;对于气液混合段压力的计算,Podio修正"S"曲线法计算出的结果比陈家琅-岳湘安法和Hasan-Kabir解析方法略高;在煤层供气充足的条件下,井底流压与产气量呈负相关关系,产气量随井底流压的降低而增加;在煤层气井排采的不同阶段,井底流压随产气量呈现不同的变化规律。

The bottom-hole flow pressure （BHFP） of coalbed methane （CBM） wells is very important for production strategy designing and management performance. According to the different drainage methods and production characteristics of CBM wells, the BHFP of CBM wells was calculated by different combination methods on the basis of the conventional gas wells BHFP calculation methods. A set of software was designed for the BHFP calculation of CBM wells and the results were compared with that of actual measured in CBM wells. The relationship between the BHFP and the productions in different drainage production period were analyzed by using the field CBM production data. The research shows that the pressure of pure gas column calculated by mean temperature-mean deviation coefficient method is higher than that by Cullender-Smith method. The pressure of gas-liquid mixture column calculated by ＂S＂ curve method corrected by Podio is higher than that calculated by the J.1 Chen-X.A Yue method and the Hasan-Kabir analysis method. The BHFP makes negative correlation with the CBM production when the CBM supply is rich and the CBM production increases with the decrease of BHFP. The change of BHFP with CBM production is different for different CBM production stage.