Fracture monitoring and analysis of propped fracture geometry in fractured coalbed methane wells in North China

Four fundamental methods are introduced,namely well temperature,ground potential survey,microearthquake and radioactivity isotope,which were used to monitor the fracture geometry of fractured coalbed methane wells in North China.Many monitoring data of fracture height and azimuth were obtained.The statistical and analytical results show that the coalbed fractures generally grow into the over and underlying coal seam,the maximum fracture height is five times higher than the thickness of fractured layer,most of the fractures are between 50 m and 90 m long,fracture shape is mainly vertical and fracture orientation exists randomness,and the extension orientation is decided by the ground stress,local structure and coal cleat together.