CBM development in China focuses on the high-rank coal

which is brittle and

during drilling

fracturing and drainage

easily crushed into coal fine. During the production

coal fine flows owing to the water flashing effect. As the water production declines

the coal fine will sediment and block the flowing channels

leading to the great reduction of coal permeability. When the coal fine enter the wellbore

it may jam the pump

resulting in accidents in production such as pump stuck or buried pump

and leading to the stop of production for well repair. In order to solve this problems

the generation mechanism

migration rules and current major controlling approaches of coal fine are summarized. And then

the mechanics model

hydraulic model and migration model are investigated respectively. According to the former studies

the coal fine migration process can be summarized as four stages: denudation

detachment

suspension and sedimentation. However

the geology conditions of coal seam in China are extremely complex and the structure changes effect is dramatic on coal basins. These factors enhance the problems of production and migration. Nevertheless

the coal fine controlling approach method primarily learns from the sanding control technology in oil reservoir and is still undeveloped for the CBM reservoirs.