Synthesis of a novel environment-friendly filtration reducer and its application in water-based drilling fluids

Abstract

Nano-lignosulfonate (Nano-LS) was formed gradually from the inside to outside through the layer by layer self-assembly method under the interaction of π-π bond and synergistic effect of ultrasound. Then acrylamide (AM) and 2-Acrylamido-2-methylpropanesulfonic acid (AMPS) were grafted onto Nano-LS in aqueous solution, potassium persulfate used as initiator. The structure of resulting the graft copolymer was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H NMR) methods. Thermogravimetric analysis (TGA) revealed the thermal stability of the graft copolymer and the results showed that the thermal decomposition of the graft copolymer was after 295.16 ℃. The graft copolymers with different additions were prepared in water-based drilling fluids (WBDFs) and the action mechanism of graft copolymer in water-based drilling fluid was revealed by scanning electron microscopy (SEM). The rheological and filtration properties of drilling fluids were evaluated before and after hot rolling (BHR and AHR) at 200.0 ℃ for 16.0 h. The results revealed that the fluid exhibit shear thinning behavior under static conditions as a gelatinous structure. When the amount of graft copolymer is 3.0 wt%, the result showed that the fluid loss (FLAPI) can be significantly reduced to 7.5 mL after hot rolling at 200.0 ℃ for 16.0 h. Moreover, the results showed that the thermal stability, salt resistance and calcium resistance of the graft copolymers are high enough to be used as effective additives in high temperature, high salinity and high calcium water-based drilling fluids.