Goldeneye: modelling a depleted field for carbon capture – how much uncertainty is left?

The Lower Cretaceous Goldeneye gas field lies in the Captain turbidite fairway of the Moray Firth and has recently ceased production. Its situation and dimensions have made it an excellent candidate for CO2 sequestration. The field was extensively modelled for the original development planning when uncertainty was assessed from the perspective of volumetrics and field behaviour. The subsequent need to assess its suitability as a CO2 store has given the opportunity for a look back at an uncertainty analysis with the benefit of full-field performance, and to perform a new analysis aimed at different issues concerning behaviour during CO2 injection.

Both sets of analyses required coupled static–dynamic modelling runs in which the key static parameter ranges of the field were varied, including depth conversion, internal geometries and aquifer properties. For the field development work the parameter ranges were explored to assess in-place volumes and field behaviour under natural aquifer and depletion drive; for the CO2 uncertainty work, however, parameter ranges were explored to demonstrate storage capacity and CO2 containment. The look-back showed that the field volumes indicated by production data landed in the upper part of the original uncertainty range and that there was definitive spare capacity in the field relative to the planned injection volume.