Nano-Engineered Polyaspartate-Coated Magnetite Scale Inhibitor: A Sustainable Solution for Efficient Gypsum Scale Control in Oilfield Operations

Scaling in oilfield applications poses considerable challenges, as it can lead to a reduction in production rates, heightened operational costs, and adverse environmental impacts when hazardous chemicals are used to prevent scale precipitation. This study addresses these issues through a pioneering approach involving green scale inhibitors (SIs). The method revolves around coating the surface of magnetite (Fe3O4) nanoparticles with a promising biodegradable inhibitor polymer, namely, sodium polyaspartate (PASP). This inventive procedure not only promotes environmentally friendly inhibition but also allows for the magnetic recycling of the inhibitor particles. The reusability of the green inhibitor, demonstrating up to 100% inhibition performance, signifies a noteworthy reduction in chemical discharge associated with scale inhibitors. In this project, the magnetic nanoparticles Fe3O4 were synthesized using the co-precipitation method, and the resulting nanomagnetic inhibitor, polyaspartate-coated trisodium citrate-coated magnetite (Fe3O4@TSC@PASP), was characterized through various techniques including X-ray diffraction (XRD), magnetometry, high-resolution transmission electron microscope (HR–TEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). In addition, the average size of Fe3O4@TSC@PASP was around 10 nm and maintained a magnetization of 13.8 emu/g postcoating. Leveraging the larger surface area provided by the magnetic nanoparticles, the inhibitor retained advantageous magnetic characteristics, facilitating efficient recycling. To evaluate its efficiency in inhibiting the gypsum scale (CaSO4·2H2O), the nanoparticles were subjected to both static jar tests and dynamic tube blocking tests. The magnetic nanocomposite scale inhibitor Fe3O4@TSC@PASP exhibited complete inhibition performance at a concentration of 1 ppm in the dynamic test and full inhibition at 2 ppm in the static test. Further scale inhibition analysis was conducted using a scanning electron microscope (SEM), revealing morphological changes in the gypsum crystal scale formation. The recyclability concept was validated, demonstrating that the magnetic nanoparticle scale inhibitor could be reused up to four times, maintaining a 100% inhibition performance in the fourth cycle. This research underscores the potential of the synthesized nanomagnetic inhibitor in providing an efficient and recyclable solution for addressing gypsum scale-related challenges in various applications.