Graphene Nanoplatelets for Extended Lifetime of Scale Inhibitor Squeeze Treatment in High Temperature Reservoir

Abstract

Abstract Scale inhibitor squeeze (SISQ) treatment is an established method for offshore fields which allows an extended effectiveness of the scale inhibitors in preventing scale deposition over time. Some of the main issues in SISQ campaign is the short squeeze lifetime being less than 1 year which may be contributed by operational and well integrity issues as well as ineffective design of the pre-flush system. This study proposed graphene nanoplatelets as pre-flush system to extend the lifetime of a conventional scale inhibitor squeeze treatment. This carbon-based nanomaterial known for its high specific surface area provided an excellent pre-coating on the rock matrix, allowing an enhanced adsorption of the phosphonate-based scale inhibitor. Special attention was given to the study on stability of the graphene nanoplatelets (GNP) in high divalent injection water and its functionalization with biopolymer to provide good dispersibility in the seawater at high temperature condition. This paper focuses on the compatibility evaluations of GNP in seawater, its dispersion and thermal stability assessment up to 96oC temperature, followed by an innovative static adsorption experiment using Berea crushed cores which served to establish the improvement in scale inhibitor adsorption at different GNP concentrations. For in-depth performance evaluations in downhole porous media, injectivity and adsorption-desorption scale squeeze treatment coreflooding experiments using Berea and reservoir native cores at high temperature conditions were then tmperformed. Finally, prediction on the field squeeze lifetime were simulated using Place-iT™ software. Results shown that the scale inhibitor's adsorption increased by more than 100% when 200 ppm of modified GNP was used as pre-flush compared to conventional pre-flush system. Good injectivity profiles, showing Residual Resistance Factor (RRF) of less than 3, coupled with slower desorption rate of scale inhibitor were observed from the coreflooding results. The simulated scale squeeze lifetime improved up to additional 14 months compared to baseline. Graphene nanoplatelets have demonstrated its versatility as nanocoating agent in enhancing scale inhibitor squeeze lifetime, extending its application as downhole high temperature production enhancement chemical.