Microseismic vector scanning-based natural fracture monitoring of the coalbed methane wells

The development degree of natural fractures is the main factor affecting coalbed methane productivity. In order to accurately obtain the distribution position of the natural fractures in the a coalbed methane field in the southern Qinshui basin, 7 refracturing wells in the area were adopted by surface microseismic vector scanning to monitor the natural fractures. A certain amount of three-component geophones were deployed around the fracturing well to collect microseismic events in the surrounding reservoir during fracturing, and after Semblance superposition, the fracture energy slices at different times in the monitoring area were obtained to explain the natural fractures in the monitoring area. Comparing the single well productivity of the well group showed a good correlation with the monitored natural fractures, revealing that natural fractures are the main controlling factor affecting single well productivity, and at the same time showed that the CBM reservoir has strong heterogeneity and natural fractures were localized. Due to the development characteristics and the relatively small scattered area, conventional 3D seismic prediction methods are difficult to identify effectively. The technology can accurately identify the development of natural fractures in coalbed methane reservoirs, and provide reliable guidance for the adjustment of well placement and measures for layer selection.