Stimulation Method And Economic Evaluation Of Low-production Vertical Coalbed Methane Wells

Coalbed methane gas(CBM)is a kind of high-quality and clean energy.The production of CBM has a significant impact to China,regarding to the optimization of energy structure,ensuring national energy security,reducing greenhouse gas emission,improving the atmospheric environment and enhancing the safety of coal mine production.China is rich in CBM resources,however,the output of most CBM wells do not meet the requirements,making poor economic payback.In this regard,relevant researches were carried out.Based on the reports,materials and data,a causal analysis was performed on the low-production wells located in Block S,focusing on the researches of well type,well deployment,drilling and completion technology,and well production.By utilizing basic conditions and parameters of the block,a production capacity forecast and numerical simulation was accomplished.Combined with the underground geological conditions and the infrastructure status on ground,the total number and specific locations of the stimulation wells were planned.Depending on the optimization of drilling and completion,geo-steering,reservoir protection and well production,an integrated stimulation approach was established.Economic evaluations were carried out on these stimulation wells.2 wells have been implemented to be experiments,which proves that the stimulation technology works well.Then 10 wells were drilled to further verify the results.The economic evaluation was performed based upon the cost of well construction,gas production,sale price,subsidy and other parameters.The dynamic payback period(DPP)of this investment is calculated to be 3.81 years,according to a conservative estimate.An overall plan of 160 L-shaped wells in 5 years were designed,which thoroughly covers the whole area of Block S.Based on a conservative estimate,the Internal Rate of Return(IRR)of the project is 28.84%,and the DPP is 6.25 years.Under the condition of mid-production forecast,the IRR is 51.60% and DPP is 4.52 years.In case of high-production prediction,the IRR is 66.91% and DPP is 4.01 years.The economic results turn to be excellent,which obviously proves the investment feasibility.