Breakthrough in operational model: testing offshore focused seismic for CS monitoring in Denmark

A new offshore monitoring solution has been tested in conjunction with CO2 injection taking place on Greensand project. The focused seismic acquisition was designed to enable frequent and reliable detection using an environmentally friendly solution, to be cost effective and to be operated even in winter in the North Sea. The approach employed was to deliberately not provide a full image of the subsurface ( Brun et al, 2022 ), but to focus the measurements on critical areas (spots) to validate or invalidate the flow model and the pre-injection hypothesis. This “predictive maintenance” approach, where the subsurface is monitored very frequently, is designed to provide early warnings of potential safety issues or CO2 plume non-conformance in a light and agile operational setup.

This paper shows how a light and agile operational model has been conducted in the winter in the North Sea while delivering high quality seismic data targeted on critical spots at the reservoir. The source used was 600 in³ and the positioning error of the source was, on average, less than 1 m between each shots. The raw seismic traces repeated over time are showing a high correlation compare to the migrated stack at the same location.