The Development and Application of a Novel Scale Inhibitor Deployment System

Abstract

SummaryWater-in-oil emulsions have been developed that have been shown to be a credible means of deploying scale inhibitors in a nonaqueous medium. Furthermore, the use of slowly degrading emulsion systems provides a means of trapping the scale inhibitor within porous media and allowing the subsequent controlled release of the chemical. This has been demonstrated with sandpack and core-flood experiments in which the inhibitor's lifetime, as measured by pore volumes of brine eluted to a given inhibitor concentration, has been extended by up to (and possibly beyond) four times compared with the base-case, nonemulsified product. No permeability damage has been observed for the emulsion systems. The use of emulsion droplets to provide chemical reservoirs within the formation also considerably reduces the nonretained chemical waste observed with conventional squeeze treatments. The nonaqueous nature of the emulsion system allows the potential ingress of the scale inhibitor into parts of the reservoir normally denied access to an aqueous-based formulation, so it can improve contact between the scale inhibitor and the reservoir fluids on production. Furthermore, the whole treatment can be nonaqueous, allowing oil continuity to be maintained during the treatment and affording rapid well cleanup post-treatment. The efficacy of the emulsion system is illustrated with the results of a successful field trial performed on the Forties field in the U.K. sector of the North Sea.