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.
Drilling fluidViscosifierHigh temperature resistantSalt resistantMechanisms of taking effect
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