Last year we introduced Distributed Acoustic Sensing (DAS) as a new method for VSP acquisition. In DAS, an optical fiber along the borehole serves as a seismic receiver array. The fiber is interrogated by a special device at the surface, sometimes referred to as lightbox. Improvements to the interrogator unit over the past year helped DAS data to approach the utility of conventional VSP data. We show results from various field trials that demonstrate the usability of DAS for typical VSP applications such as checkshots, imaging and time-lapse monitoring. We conclude that DAS would enable VSP, and cost-effective time-lapse VSP, in a broad variety of wells, particularly those inaccessible by geophones.
Advances in Distributed Acoustic Sensing for VSP