Abstract: Because the microseismic signals are very weak, it is difficult to accurately pick up the microseismic events in the microseismic surface monitoring. To automatically identify microseismic signals, a discriminant frequency estimation algorithm of pattern recognition method based on STA/LTA was proposed in the article. This method can pick up low-energy microseismic events that could be missed by setting a threshold, and it is faster than traditional STA/LTA. In this paper, we also utilize amplitude stacking to locate the source of microseismic events. By analyzing the focus of energy of the stacked amplitude, false events can be further eliminated. Therefore, the method can describe the development of the underground cracks more accurately. Finally, the method is verified by a fracture monitoring experiment around a horizontal well in northern Hebei Province. The results show that the method is highly efficient in computation and the monitoring results are accepted by the fracturing operators. It can provide theoretical guidance to the subsequent fracturing operations.

Key words: microseismic monitoring, short and long time window, microseismic event, energy focus, frequency estimate, oil field development