From Microseismic to Induced Seismicity: Monitoring the Full Band of Reservoir Seismicity

Summary Seismic monitoring is an important tool for evaluating hydraulic fracture treatments in many petroleum reservoirs. Microseismic data is used to determine the extent of fracturing due to treatment and evaluate how effectively the reservoir is stimulated. Induced seismicity monitoring has become important recently, as the occurrence of high magnitude (MW > 0) events in several locations has led to the introduction of government-mandated “traffic light” systems to mitigate the impact of induced seismicity on the general public. To better understand the reservoir conditions which lead to the generation of large events, these two different ways of measuring seismic activity can be combined, incorporating the highly accurate event location accuracy from downhole microseismic monitoring with accurate source characterization of high magnitude events from surface induced seismicity monitoring. Such a monitoring system allows the full range of seismicity related to hydraulic fracture treatments to be accurately characterized. Combining the recorded data is a technical challenge, but with attention to detail in applying relevant corrections it is possible to achieve a consistent dataset. Data from a large multi-well zipper frac employing the full-band monitoring configuration is discussed in detail to illustrate the benefits of an integrated processing workflow in terms of increased understanding of the fracture process and conditions which lead to high magnitude events.