Next Generation Repurposing: Harnessing Refractions in Legacy 3D Seismic via the Direct-Calculation Refraction (DCR) Method

The footprint of legacy 3D seismic across the UKCS and other regions of the North Sea is extensive. In many cases there exists substantial overlap with the positioning of offshore wind farms in early planning and development phases but, in their present state, they hold little value for offshore wind farm site characterisation. We present two case studies where repurposing vintage 3D seismic over offshore windfarm sites has been proven to provide enormous uplift for site characterisation. Repurposing has provided the opportunity to utilise the full potential of the acquired legacy 3D seismic. A direct-calculation refraction (DCR) velocity modelling technique is described here. This has proven to be a robust and cost-effective method for obtaining key velocity information in the near-surface down to about 200m BSB.