Detection of Out-Of-Zone Growth in Multi-Stage Hydraulic Fracturing by Microseismic Monitoring

Out-of-zone growth in multi-stage hydraulic fracture treatments can be detected by analysis of microseismic multiplets. This novel technique allows detection of the out-of-zone growth when we observe a repeated hydraulic fracturing of the part of the reservoir which has been fractured in a previous stage (i.e. cross-stage fracturing). The cross-stage fracturing is detected by automated identification of multiplets, i.e. microseismic events with similar source mechanisms and nearly identical locations. We applied multiplet identification to detect the cross-stage fracturing on two hydraulic fracture monitoring datasets (Canyon Sand and Barnett Shale Formations) one of which is described in this paper. We verified this detection method with the initial microseismic events locations. The cross-stage fracturing was detected only a few minutes after the first microseismic events were detected. <br>The computation cost of this new multiplet identification method is a fraction of a second per detected microseismic event, thus making this application suitable for real-time monitoring. The identification of the multiplets provides additional information to the locations of microseismic events and can be used to verify or justify change during hydraulic fracturing treatment. The early detection of the cross-stage fracturing could lead to real-time adjustments of the hydraulic fracturing. <br>