Production layer combination selection for coalbed methane development in multi-coal seams based on cluster analysis

In multi-coal seams,coalbed methane(CBM) production layer combination is a key to the latter multi-layer co-production. Taking the CBM development well in Yuwang block from Laochang in Yunnan as an example,five key parameters including thickness,burial depth,reservoir pressure gradient,permeability and CBM content of multi-coal seams were selected,using SPSS software and Q-type clustering method,outputting tree-like spectra,multi-level pro- duction layer combination were analyzed. According to the distance between classes,the clustering results could be di- vided into four major levels,corresponding to four combinations,the higher the level,the higher the similarity between production layers,the better the combination. Generally,the combination of level 3 or level 4 was the optimal combina- tion. It was found that most of the interface coal seams in the clustering category correspond to the key interface coal of coal seams measures or the regional caprocks,which essentially reflected the inherent control of geological processes. The Q-type clustering was used to divide the production layer combination of the CBM exploration and development wells in Yuwang block. The research showed its results were more consistent with those by other methods. According to the clustering analysis of CBM development wells in the previous period,the higher the similarity,the closer the class spacing,the better the CBM producing effect. In summary,clustering analysis method was an indirect and effective method of production layer combination.