Characteristics of water yield and its influence factors during coalbed methane production in Liulin area

Abstract：On the basis of actual producing data, combined with the fluid inclusion studies, this paper analyzed the characteristics of water yield and its influence factors during CBM production in Liulin area from the paleo and present hydrogeology, production model and fracturing technology. The results show that the water yield in Liulin area comes from the common action of many factors. The coal seam roof sandstone aquifer of Shanxi Formation, in which the paleo- fluid presents detained feature, has relatively weak water yield property and its present water yield has a direct rela- tionship with the distribution of fracture. The coal seam roof limestone aquifer of Taiyuan Formation has a communica- tion with surface fresh water in the early stages, which has relatively strong water yield property. During the production by different model, under the influence of fracturing strength and the differential communication of coal seam with roof aquifer, the water yield shows gradual increasing by the order of model D, A, B, and C. We further point out that in or-der to depress influence of hydrogeology, some horizontal wells can be selected in proper area, the production of CBM can be carried out from northeast to southwest which is favorable for drainage and pressure lowering of coal seam, and fracture size can be decreased, especially the height of vertical fractures.