Treatment technology and method of low-to-moderate production coalbed methane wells in Hancheng mining area

Hancheng mining area has a great number of coal seams and abundant reserves. However, faults are widely developed, the single layer is thin, and the porosity and permeability are low. The drainage time is long, the production fluctuated seriously during the producing process. There is a high ratio of low-to-moderate production wells in Hancheng mining area. It is an urgent subject to improve single well production, which faces the current coalbed methane development in China. The influencing factors that affect low production wells are analyzed according to geological and engineering aspects. Firstly, the production layer is thin and the reserve controlled by single well is limited. Secondly, the physical property is poor and the production is low. Thirdly, the faults communicate with fracturing fractures, and water has channeling between adjacent layers. Fourthly, the cementing quality is poor or even has no well cementation in shallow layers, causing cement channeling outside casing. Fifthly, the fracturing measure does not meet the designed scale, and the effective seepage radius is small and the stable production period is short. Sixthly, the draining and producing system is unreasonable, leading to stress sensitivity of permeability, and the production declines sharply. According to the research results, corresponding adjustment plan and measures are put forward, including optimizing perforated layers to increase production layer thickness; using multiple fracturing technology in the appropriate production stage to improve seepage area; plugging workover for channeling wells; drilling sidetracking horizontal wells after plugging old wells for well channeling along faults; establishing a reasonable draining and producing system to prolong the stable production period through permeability project intervention. The results have achieved good results in practical application and provide reference for the development of the same type of mining area.