Multi-Fibre DAS Walk-Away VSP at Kapuni

As part of a field appraisal campaign in New Zealand, a set of walk-away VSP-s was acquired. That included a state-of-the-art geophone acquisition in two wells and a simultaneous multi-fibre DAS VSP in one of those wells. All VSP data were of excellent quality and provided high-resolution images. The DAS data exceeded expectations in terms of quality and resolution, aided by simultaneous acquisition on 5 fibres in the same cable. Here we discuss in more detail the benefits and complications of a multi-fibre DAS acquisition. The main benefit is that the signal-to-noise ratio of DAS can be improved without extra source effort, and at negligible extra cost for fibre installation. In addition, the multi-fibre acquisition provides opportunity for DAS channel depth QC and refinement. The main drawback is the cost of employing additional DAS interrogators for the extra fibres, as in this case the fibres were not looped in the cable.