Production Performance Forecasting Of Coalbed Methane Wells

CBM production performance forecasting is very substantial in project viability study,optimization,maximization of methane recovery and general reservoir management.Building on the benefits of CBM forecasting,this research was focused towards understanding the factors influencing peak gas rate and peak time.Ultimately,establish a mathematical formulation for predicting these parameters.To attain the aforementioned objectives,a CBM reservoir geological model was constructed for investigating these factors.CMG numerical simulator was employed.Gray analysis and multiple linear regression using Minitab software were together used to establish mathematical formulations for predicting peak gas rate and peak time.Fourteen factors were found to influence peak gas rate.These are:-drainage area,seam thickness,cleats absolute permeability,cleats porosity,desorption time,Langmuir volume constant,and Langmuir pressure constant.Other factors includes;critical desorption pressure,cleats water saturation,water relative permeability exponent ‘m’,gas relative permeability coefficient ‘k,’ gas relative permeability exponent ‘n’,bottomhole pressure and skin factor.Similarly,thirteen factors were found to influence peak time.These are: drainage area,absolute permeability,cleats porosity,desorption time,Langmuir volume constant,Langmuir pressure constant,critical desorption pressure,cleats water saturation,water relative permeability exponent ‘m’,gas relative permeability coefficient ‘k’,gas relative permeability exponent ‘n’,bottomhole pressure and skin factor.To sum up,it was concluded that,coal thickness,cleats absolute permeability and Langmuir pressure constant were most strongly influencing factor on peak gas rate while critical desorption pressure,Langmuir pressure constant,and drainage area were the most influencing factor on peak time.