Barium sulphate scale is a major problem in the BP Magnus field, even at low water cuts (<1%). In the late 1990’s BP Magnus adopted a policy of performing pre-emptive scale squeeze treatments on newly completed wells to prevent scale deposition and maintain well productivity on water breakthrough.
Squeezing dry and low water cut wells with aqueous inhibitor treatments can cause formation damage and result in changes in near well bore wettability. At this time, core flood studies carried out with conventional aqueous based inhibitor treatments indicated that it was possible to safely deploy these treatments in BP Magnus core material. A successful field trial was performed in 1998 since when it has been standard practice on the BP Magnus asset to pre-emptively treat dry and low water cut wells with aqueous inhibitor treatment packages.
Over the last few years a range of non-aqueous treatments technologies have been developed including oil miscible, emulsion and truly oil soluble scale inhibitors. Laboratory core flood studies have therefore been performed with these technologies, as they were developed to compare and contrast their performance to the use of aqueous based scale inhibitors.
This paper will detail a comparison of the core flood studies with both non-aqueous and aqueous based inhibitor treatments and will highlight that it is not always necessary to perform non-aqueous based treatments in dry and low water cut wells. An economic comparison of non-aqueous and aqueous based inhibitor treatments will be presented and, in addition, the paper will present the field experience gained to date with aqueous pre-emptive squeeze treatments in the BP Magnus field and outline the future scale management strategy for treating multi-lateral wells.