Non-aqueous vs aqueous overflush scale inhibitor squeeze treatment in an oilfield offshore Norway

The objective of this paper is to compare squeeze treatment lifetime achieved by conventional aqueous and non-conventional squeeze treatments, where non-conventional refers to treatments where the overflush is split into aqueous and non-aqueous stages, typically diesel being used for the non-aqueous stage. The simulation and optimisation calculations were performed using a specialised near wellbore model for scale treatments, where a two-phase flow model was used to describe the displacement process during the multi-stage overflush. Splitting the overflush was found to reduce the squeeze lifetime marginally, as the non-aqueous overflush is not as effective as a purely aqueous overflush in propagating scale inhibitor deeper into the formation. However, this is counterbalanced by the fact that a smaller volume of water needs to be injected in the formation, and so reducing the risk of formation damage and most important for this particular case, a smaller volume of water will need to be lifted, so the well may be set back to production with ease.