Synthesis And Performance Study Of Betaine Copolymer Fluid Loss Agent PADAN

With the increasing requirements of drilling fluids for deep well drilling,it is necessary to establish a drilling fluid formulation system resistant to high temperature and salt calcium intrusion to ensure the safety and drilling speed of ultra-high temperature deep wells.As the core treatment agent for drilling fluid,fluid loss additive must have stability,fluidity and inhibition under high temperature conditions.Based on this,this paper designed and prepared a novel of sulfobetaine drilling fluid loss additive based on salt tolerance,high temperature resistance and inhibition.In this paper,1,3-propanesultone and N-(3-dimethylallyl)methacrylamide(DMAPMA)were used to synthesize 3-(2-methyl acrylamidopropyldimethylamino)propane sulfonate(DMAPMAS).Then copolymer named PAD AN,which was used as fluid loss additive for frilling fluid,was synthesized through grafting AMPS,NVP and DMAPMAS onto the backbone of AM via the method free radical polymerization in aqueous solution.The synthesis condition with optimal property were that m(AM:AMPS:NVP:DMAPMAS)=60:20:6:14,initiator was is 0.6%of the total mass of the monomer,the total mass fraction of the monomer is 30.0%,pH is 7.0,the reaction time is 5 h,and the reaction temperature is 55 ?.FT-IT and1H NMR analysis showed that the synthetic fluid loss additive met the design requirements.Thermal analysis indicate that the fluid loss additive PADAN had good thermal stability,and no significant thermal degradation of the fluid loss agent occurred before 313?.The solution performance,fluid loss performance,temperature resistance,salt resistance and rheology of the fluid loss reducer PADAN were systematically evaluated.The experimental results showed that when the PADAN addition amount is 2.0%,the API filtration loss of freshwater base slurry and composite brine base slurry after aging for 16 h at 200? is 4.3 mL,3.2 mL,16.6 mL,and 19.2 mL,respectively.When the NaCl mass fraction is 36%,the API fluid loss of the 2.0%polymer drilling fluid system is 4.0 mL.The API water loss of 2.0%polymer drilling fluid system before and after aging at 160? for 16 h is 4.8 mL and 18.8 mL when the mass fraction of CaCl2 is 1.0%.The inhibitory properties of PADAN and JT-888,SP-8 and MAN104 under the same conditions were studied.The results showed that the HJ-3 inhibition performance of PADAN was better than the other three treatment agents.The effect of copolymer fluid loss agent PADAN on the morphology and particle size distribution of drilling fluid mud cake was studied by scanning electron microscopy and laser particle size analyzer.The results of scanning electron microscopy showed that the copolymer fluid loss additive enhanced the dispersion of clay particles in the high temperature salt and calcium environment through adsorption and encapsulation,and improved the filter cake quality of the drilling fluid.According to the analysis of laser particle size analyzer,the addition of PADAN increases the proportion of fine particles with the particle size of 0,1?m-1?m and stabilize the clay particles.The median diameter and average diameter decrease,and the particle size distribution of the drilling fluid become more reasonable.Synthetic PADAN is a fluid loss additive with better fluid loss and temperature resistance compared to the four commonly used fluid loss additives FT-1,SMC,YN-1 and JT-888.The compatibility study shows that the combination of PADAN and sulfonated polymers SMC,SMP-? and SPNH in the drilling fluid system can effectively reduce the fluid loss of the drilling fluid and improve the rheological properties of the system.According to the results of adaptability evaluation,PADAN has a significant fluid loss reduction effect in the sulfonation drilling fluid system and the polysulfide KCl drilling fluid system,with good compatibility and little influence on the rheological properties of the drilling fluid system.