Study on secondary fracturing candidate selection of coalbed methane based on clustering analysis

After years of first fracturing of coalbed methane wells in Shizhuang south block of Qinshui basin, Shanxi province, the overall gas production has declined, and it is urgent to carry out secondary fracturing to improve the production capacity, and the selection of target wells has a very important impact on the design and construction of secondary fracturing and the stimulation effect.In order to solve the problem of low number of secondary fracturing test wells and limited number of samples in the block, the method of fracturing candidate based on clustering analysis is proposed.Considering geological reserves, compressibility and engineering factors, the hierarchical clustering model of secondary fracturing well selection is established; according to the characteristics of construction curve, fracturing risk short-circuit conditions are set to exclude wells with high overpressure risk.Combining with clustering integration algorithm, the secondary fracturing potential of each well is finally determined.Taking 15 wells in this block as examples, the potential of secondary fracturing for each well is determined, and B01 well is selected as the target well.After the secondary fracturing, a good stimulation effect was achieved.This study can provide an effective method for well and layer selection under the condition of limited number of wells, and providing basis and reference for subsequent fracturing production.