Improvement of rheological properties of invert drilling fluids by enhancing interactions of water droplets using hydrogen bonding linker

The conventional method to improve rheological properties of oil based muds (OBMs) by dipersing organoclays in continuous oil phase has generally been considered inefficient and deficient. This paper presented a new method to improve the rheological properties by using a hydrogen bonding linker (HBL) that can replace organoclay to enhance the interactions of water droplets through hydrogen bonding. Hydrogen bonding linker was synthesized by reaction of dimer acid and diethanolamine in the presence of TiCl4 as catalyst at 130 degrees C, and characterized by FTIR. Emulsions with different concentrations of HBL were then characterized by bottle tests, focused beam reflectance measurements (FBRM) and rheological measurements. Experimental results show that optimum stability is achieved when the concentration of HBL is 2 g/L. But when concentration of HBL exceeds 2 g/L, the trend of instability is increasingly stronger because HBL leads to coalescence of water droplets. Emulsions with HBL demonstrate a more fragile gel structure and a stronger thixotropic behavior than emulsion without HBL. The application of HBL in an organoclay-free OBM shows that a higher yield point (YP), higher Gel strengths and a higher electrical stability (ES) were achieved in comparison with the conventional OBM. (C) 2016 Elsevier B.V. All rights reserved.