Curve types about water and gas production and their formation mechanism of coalbed methane in Changcun coal mine

The curve types of water and gas production of coalbed methane wells is a comprehensive reflection about the potential of geology and reservoir and the drainage system reasonable or not.According to the curve shape of daily water and gas production of 33 CBM wells in Changcun coal mine, combined with the method of volatility index discrimination, five typical curve types of water and gas production are classified.This paper analyzes the formation mechanism of typical curve types of water and gas production from the aspects of gas production potential of reservoir resources, surrounding rock supply and drainage system, The results show that the production curve of Changcun coal mine can be divided into single peak water production and stable gas production type, double peak water production and double peak gas production type, double peak water production and stable gas production type, stable water production and single peak gas production type, stable water production and stable gas production type and so on.When the surrounding rock water is almost no supply or less, and the resource potential is large and the drainage and production system is reasonable, it generally shows the stable gas production and single peak water production type; when the drainage system is unreasonable, it is easy to appear the stable gas production and double peak water production curve.When the water supply of surrounding rock is more and the resource potential is small, it generally shows stable water production and single peak gas production; when the resource potential is general or large, it is stable water production and stable gas production type.When the surrounding rock water supply is small, the resource potential is general and the drainage and production system is unreasonable, it is easy to show the double peak water production and double peak gas production type.The research results have laid a foundation for the optimization of drainage and production system under different geological conditions.