Development and Performance Evaluation of a High Performance Drilling Fluid Viscosifier

A high performance viscosifier DV-1 has been developed to solve the problem of degradation and losing effectiveness of drilling fluid viscosifiers in high temperature and high salinity conditions. VD-1 is synthesized through free radical copolymerization with monomers such as MAPS, MAC and NVP. The initiator of the polymerization reaction is AIBA. The optimal reaction condition, determined through orthogonal experiment method, is as this: reaction temperature is 50 ℃, concentration of the monomers is 40%, concentration of initiator is 0.4%, and reaction time is 4 h. The reaction product was characterized using FTIR, ¹H-NMR and TG-DTA, and the viscosifying capacity, high temperature high salinity performance and the ling-term effectiveness of the synthesized product were evaluated. The evaluation experimental results show that 1% water solution of DV-1 has apparent viscosity of 44.7 mPa∙s. After aging at 180 ℃ for 16 h, the viscosity of the water solution is still maintained at 53.2% of its original viscosity. DV-1 is resistant to the contamination of salts. DV-1 also has good long-term effectiveness; after aging at 180 ℃ for 72 h and 120 h, the viscosity of the solution is still maintained at 50.5% and 40.7% of its original viscosity. DV-1 has EC₅₀ of 30 200 mg∙L⁻¹, meeting the standard of discharge in offshore area. The viscosifying mechanisms of DV-1 are studied by observing the spatial 3D morphology and by analyzing the Zeta potential of DV-1 in solution, it is concluded that DV-1 viscosifies in solution because the molecules of DV-1 have stable main chains and rigid side chains, the amphoteric ionic structure inhibits the continual curling of the side chains, thus effectively improving the salt resistant performance of DV-1 as a viscosifier.