The penetration of water-based drilling mud into the formation in the drilling is a serious issue that causes wellbore instability. Here, a polymer-grafted graphene nanosheets (Gr-AM) was prepared as an inhibitor in water-based drilling mud. The polymer was prepared via free radical polymerization using precursors of acrylic acid, melamine, and graphene. Fourier transform infrared spectroscope (FT-IR) and transmission electron microscopy (TEM) were utilized to characterize the prepared polymer. Thermogravimetric analysis (TGA) was employed to evaluate the material's thermal stability. Several inhibition tests were carried out such as shale recovery test, anti-swelling parameter, and immersion analysis. The results showed that the Gr-AM could be stable up to 240 °C. The low concentration of Gr-AM achieved good inhibition performance compared to AM and KCl as common inhibitors. The results of this work offer some technical ideas for developing of high-performance shale inhibitors..
