Synthesis Of Zwitterionic Emulsifier And Study Of High Temperature Resistant Oil-in-water Drilling Fluid

Oil-in-water emulsion drilling fluid is a kind of important low-density drilling fluid system,it has good effects of leak protection and formation damage control when applied in the low pressure carbonate formation characterized by extremely developed fractures and pores,which make this drilling fluid widely used in field drilling operation.With the growing demand of exploration and drilling technology used in deep formation,the higher requirement is put forward on the temperature-resistant properties of oil-in-water emulsion drilling fluid.This paper studies emulsifier with high-temperature tolerance and then develops a temperature-resistant oil-in-water emulsion drilling fluid.Firstly,the paper discusses a method of producing sulfobetaine type zwitterionic emulsifiers.Sulfobetaine type zwitterionic emulsifiers of different carbon length are synthesized in one step,and the best optimum synthesis conditions are optimized by the single factor experiment:the mole ratio of 1,3 propane sultone and long chain alkyl dimethyl amine is 1:1.15 the reaction temperature is 65?,the reaction time is 3h and the solvent is isopropanol.Under the optimal conditions,the transformation rate of tertiary amine is approximately 98%,and the yield is 84.7%.The structure of products are characterized by Flourier transformation infrared spectroscopy and 1H nuclear magnetic resonance.Secondly,some surface properties of sulfobetaine aqueous solution are studied.The results show that critical micelle concentrations change small before and after 200? aging experiments,the data are as follows:cmc(12C)=5.13×10-3mol/L,cmc(14C)=5.25×10-4mol/L,cmc(16C)=5.50×10-4mol/L,cmc(12C)'=6.31×10-3mol/L,cmc(14C)'=5.62×10-4mol/L,cmc(16C)'=7.24×10-4mol/L,which indicates sulfobetaine keep surface activity after aging experiments.Dynamic interfacial tensions of different sulfobetaine aqueous solution reach to stable lowest level after a while,interfacial tension present downward trend with the increase of carbon length.Different sulfobetaine aqueous solution reach optimum emulsification to liquid paraffin at 2.0g/L(12C),1.0g/L(14C),3.0g/L(16C),among them,dodecyl sulfobetaine shows the best emulsifying effect to liquid paraffin.Three sulfobetaines exhibit different foaming property in the order of 14C>12C>16C,and stability of foam in the order of 14C>16C>12C.Finally,formula screening and optimization of oil-in-water emulsion and the drilling fluid are made,the optimized formula is the following:2%Sodium bentonite slurry+3%PF-SMP+4%SPNH+0.4%Dristemp+0.4%FA-367+3%Soltex+0.3%NaOH(aqueous volume)+l%Dode-cyl sulfobetaine+P135(mass ratio 3:1)+0.2%Silicone defoamer,water-0#diesel volume ratio 5:5.This drilling fluid system has excellent properties,temperature tolerance is about 200? and also has the ability to resist some contaminants(20%water,20%oil,2%salt and 15%dolomite cuttings),so it can meet the drilling and geology requirements of deep formation.