Transport and return of an oilfield scale inhibitor reverse micelle nanofluid: impact of preflush and overflush

Abstract

In this study, oilfield scale inhibitor reverse micelle nanomaterials and a nanomaterial fluid (nanofluid) were investigated to expand their use in the delivery of a scale inhibitor into reservoir formation for oilfield mineral scale control. The prepared inhibitor nanomaterials are in a non-aqueous medium designed for application in low water cut or water sensitive production wells. The transport behavior of the inhibitor nanofluid was evaluated with a focus on examining the impacts of flow rate and preflush fluid. It shows that an increase in flow rate can improve the transportability of the nanomaterials in a calcite medium. The increase in flow rate can also lead to a reduced tendency of nanomaterials to be collected by a calcite medium. An isooctane preflush can enhance the transport of the nanomaterial compared with an aqueous brine preflush. Inhibitor return performance of the nanofluid was evaluated by laboratory squeeze simulation tests. It shows that the prepared inhibitor reverse micelle nanomaterials demonstrated an extended squeeze lifetime compared with the conventional pill solution. Furthermore, it is evident that an aqueous brine overflush can improve the return performance of the nanomaterials, compared with an isooctane overflush. This can be explained by the adsorption–desorption dynamics of the previously attached nanomaterials. Laboratory transport and squeeze simulation studies suggest that the inhibitor nanofluid has the potential to serve as a delivery vehicle to improve placement and return of inhibitors inside formation for oilfield scale control.