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

The bottom-hole flow pressure (BHFP) of coalbed methane (CBM) wells is very important for production strategy de-signing 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 meth-ods. 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.l 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.