Study on productivity prediction model of horizontal coalbed methane well and its applicability

in order to accurately choose suitable productvity prediction model for different production type coalbed methane wel.according to the mathematical statistic theory and case analysis,the paper discussed the effiency,sutability and dfference ofthe Weng model,.month producion/accumulated production ratio model and gray system model based on the time sequence in the iting and prediction of coalbed methane horizontal wels.The study showed that the above three models could all well fiting on the production history of the coalbed methane wels could make the accurate predictions and could have differences in each model.The Weng model could make an accurate prediction for the wells with a stable variaton production and a smalfuctuation and when a high fuctuation occurred,the prediction would have a high eror.The month production/accumulated production ratio model couldbe applied to the middle-long term prediction and would be affected by the decreasing lavw.The gray system model would have a igh fiting and high prediction accuracy to the decreasing stage of the production wells and the eror would be increased with the fluctuation of the decreased data.Therefore,he models should be selectively applied according to the production stage,production features and purpose of the coalbed methane well.