Transformative changes in Distributed Acoustic Sensing (DAS) hydraulic fracture and VSP monitoring

Two recent changes in Distributed Acoustic Sensing (DAS) hydraulic fracture and VSP monitoring are, in the authors’ opinions, worthy of the term transformative. Firstly, engineered fibers provide an improvement in DAS acoustic sensitivity of 20 dB or more, and commonly allow detection on the order of thousands of microseismic events per stage in the Wolfcamp Formation of the Permian Basin, USA, and a typical listening distance of 1,000-1,300 meters depending on the definition of listening distance. Secondly, it is no longer necessary to go to the expense and risk of cementing fibers behind casing to get good quality DAS data. Fibers in wirelines that are simply lying inside the casing of a horizontal well, coupled only by gravity and friction, produce good data quality for both DAS acoustic waves and slow strain data. The deployment and use of temporary DAS fibers is far less expensive than that of permanent fibers.