Real-Time Hydraulic Fracturing Monitoring via Distributed Acoustic Sensing (DAS) Acquisition of Pumping Noise

Summary The strong and regular acoustic signal provided by working pumps spreads along a fractured well depending upon the propagating fracture geometrical and physical attributes, therefore, one can devise fracture properties by interpreting downhole DAS data. We describe a quantitative DAS data inversion workflow and give a synthetic example of hydraulic fracture monitoring. Specifically, profiling the wellbore in real time in terms of Normalized Injectivity Indices (NII) calculated out of DAS pump noise data is described, and inversion for fracture parameters by matching NII to a forward model of pulse propagation in a fractured wellbore is outlined. The attractiveness of the proposed method is that the pumping noise is present at each frac job and that every pump generates a plurality of harmonic frequencies, thus there’s always plenty of data for inversion. We also stress that interference of the pump signal with the flow noise should be accounted for in DAS interpretation.