Combined CBM production behavior and development strategy of multiple coal seams in Zhijin block

Aiming at the problems that the CBM layers are numerous and thin, it is difficult to develop it effectively in south China, on the basis of the actual production data of CBM wells in Zhijin block, the production characteristics and the influencing factors of gas production of the directional wells for co-extraction of different seams and the horizontal wells for thin seams were analyzed, and corresponding suggestions for CBM development were put forward. The analysis indicated that the gas production of co-extraction of different seams was quite different, was influenced by the liquid-supplying capacity of formation, the height of desorbing liquid surface and the span of co-extraction, the effect of co-extraction of middle and lower seams was better than that of co-extraction of the upper, middle and lower seams, of them the co-extraction of seams 16,17, 20, 23, 27 and 30 was the optimal horizons for co-extraction in the block; The fracturing scale influenced significantly the gas production result of CBM wells, the bigger the fracturing scale, the better the gas production result, increasing the fracturing scale and enhancing the fracturing reformation effect are the important approaches for effec-tive development of multiple seams; The gas production of horizontal wells is 3-4 times higher than that of directional wells, the adaptability of horizontal wells for thin seams was confirmed. According to the geological and surface conditions, using horizontal wells and directional wells for combined development can improve the development effect of multiple seams. It is comprehensively considered that optimization of co-extraction horizons in an area with favorable geological conditions, in-crease of the fracturing scale, optimal use of horizontal wells will improve the development effect of multiple thin coal seams. methane well. The larger the fracturing scale is, the better the gas production effect will be. Increasing the fracturing scale and improving the fracturing transformation effect is one of the important means to effective development of multiple thin coal seams.