Fracture Imaging Using DAS-recorded Microseismic Reflections

Distributed acoustic sensing (DAS) is a rapidly developing technology that can be used for characterizing the geometry and propagation of hydraulic fractures. DAS provides observations of microseismic wavefields with high spatial resolution, which contain direct P- and S-arrivals as well as converted and reflected signals. In addition to traditional approaches for microseismic event location and source mechanism analysis, DAS-recorded reflections can be used to image induced fractures. Simulation shows that the reflections may be tuning response of hydraulic fracture 'corridors' from earlier treatment stages. We have developed a straightforward processing workflow based on ƒ-k filtering and ray-tracing image hydraulic fracture using the reflected S-waves, which can convert DAS-recorded data in the time domain to fracture map in the space domain. In addition to excellent agreement with frac-hits from low-frequency DAS, the proposed workflow can image the extent of hydraulic fractures away from the monitor well. The method can further provide time-lapse images of 3D hydraulic fracture evaluation to complete the fluid and fracture monitoring during stimulation.