Calculation of coalbed methane reserves and economic evaluation of Lishu Coal Mine in Jixi Basin

To demonstrate the economy of developing surface CBM in Lishu Coal Mine, according to the standards of coalbed mechane resources and reserves, un its of reserves calculation were demarcated, and the coalbed methane reserves of No.14 coal seam in Lishu Coal Mine was also calculated by the volume method, whi ch showed the control reserves of the whole region was 3. 58x 108m3, the proven geological reserves was 0.91x 10~8m3, which belonged to medium depth, small reserv oir.On the basis, the coalbed methane development project was designed, relevant economic evaluation was also carried out.The results showed that all economic indic ators of CBM development were good, the financial internal rate of return after tax was 12.23%, higher than the benchmark rate of return ( 8%) , the financial net prese nt value after tax was 60.480 3 million, the investment recovery period after tax was 6.60 years ( less than 8 years) .The development of coalbed methane was feasible. After drainage 15 years, single well cumulative production reached 422.64x 10~4m3, the recovery rate reached 48.94%, correspondingly, gas content ( average) was re duced to less than 8 m3/t, gas pressure was reduced to about 0.74 MPa, which has achieved the purpose of eliminating regional gas outburst.