Surface modification of superparamagnetic nanoparticles for enhanced oil recovery: A review

It is no secret that nanoparticles are promising material which have been used to improve the efficiency of enhanced oil recovery (EOR). Superparamagnetic nanoparticles (SPNs) are material often used in EOR due to their superior properties namely high surface-to-volume ratio, excellent superparamagnetic abilities, high thermal stability, and ease of fabrication. However, SPNs are known to be hydrophobically weak and prone to aggregation due to its magnetic nature and high surface charge. To minimize this issue, surface modification have been employed to reduce the agglomeration of SPN. This review paper discusses the development and performance of SPNs post surface modification from EOR perspective. Firstly, this paper details the synthesis methods of SPNs fabrication and the key parameters influencing their synthesis. The discussion also covers the types of surface modifiers and critical parameters in EOR applications. Furthermore, this review paper highlights the mechanisms involved in EOR application in which surface modifier was applied to improve the performance of the SPNs. Finally, this review includes discussion on modelling, simulation works and field trials. Based on the reviewed literature, it seems that surface modification of SPNs tends to exhibit excellent stability. This, in turn, leads to higher oil recovery rates of up to 73%. By varying the surface modifications of SPNs, promising results can be achieved such as a low contact angle of up to 14.7 degrees, indicating a strongly water-wet state; a mobility ratio of 0.86, which is less than 1 and signifies an adequate sweep efficiency; and a significant reduction in interfacial tension from 3.7mN/m to 0.84 mN/m, a reduction of 77%. To gain deeper insights into the potential of SPNs, further studies which involve modelling of interaction between the modified SNPs and porous media under reservoir condition should be initiated.