Production Declines of Kansas Coalbed Methane Wells as a Function of Their Production Rate and Age

Do highly productive coalbed methane (CBM) wells decline differently than poorly productive CBM wells? Analysis of natural-gas production data for southeastern Kansas CBM wells indicates there is no significant difference in annual decline rates of prolific wells compared to less productive wells for most of their lifetime, except for two years after the wells achieve peak production. Although annual production-decline rates are substantial for the first year of production after the peak month of production (∼35%) these decline rates lessen with increasing age of the wells. Production declines stabilize to 12 to 13% per annum after about 5 years of production. Year-to-year production data are more variable for less-productive wells because slight changes in production in poorly productive wells can markedly affect their decline calculations. Approximately one year is necessary for a CBM well to reach peak production. After peak production is achieved, the more prolific CBM wells decline at rates faster th...