Reprocessing and repurposing of historical O&G data for offshore renewable projects

Repurposing of pre-existing O&G exploration data can enhance initial site evaluation and subsequently allow for the specification of more targeted reconnaissance offshore geophysical surveys to optimally provide the high-quality information needed during the development of offshore windfarm sites. During early development, key decisions are made that can have long-term consequence for the viability of the project. Typically, there is little or no site-specific information available about the potential ground conditions on which to base those decisions, beyond broad scale published geological mapping and the occasional borehole. Any detailed engineering design needs to wait until costly and time-consuming offshore surveys have been completed. Many offshore areas have been surveyed for O&G with the data now held in archive. As the target depths for O&G exploration and turbine foundations are different (e.g., 2km vs 100m), the data typically is not optimised to provide the resolution required within the zone of interest for turbine foundations. However, reprocessing the data with a focus on maximising the imaging of the very shallow section can reveal previously hidden details allowing the development of preliminary 3D ground models for windfarm areas and early engineering design. This paper will describe how this approach was used for an offshore windfarm project in the North Sea.