Learnings from Distributed Acoustic Sensing Data Processing for Seismic Applications - A Case Study from the North Sea

Use of Distributed Acoustic Sensing (DAS) fibre-optic technology for acquisition of vertical seismic profile (VSP) data is increasing rapidly. Since 2012 BP has carried out and participated in several field studies using DAS across different basins. These tests have included acquisition on land, in deep and shallow water, with sources deployed as a walk-above spread and shot patches of 60,000, using pre-installed fibre in producing wells and highly deviated wellbores. This paper will discuss the results and experience gained from acquisition and processing of the dual-well 3D DAS VSP over the Valhall field in the North Sea in 2015. This survey had a larger shot patch than previous trials, was acquired in shallow water and one of the wells remained on production throughout; a scenario presenting various challenges and opportunities. Successful imaging of the data confirmed the technical utility of DAS in achieving a targeted subsurface image and results indicate that recording data acceptable for imaging may be possible in producing wells.