Development Of Fluid Loss Additive Of Phosphoaliuminate Cement System

A fluid loss additive for a new CO2-corrosion resistant cement slurry-phosphoaliuminatecement system was developed. Through optimization of cement fluid lose additives and drillingfluid filtrate reducers, merits and demerits of this admixtures used in phosphoaliuminatecement system were analyzed. Based on this, aerylamide(AM)、2-arcyamido-2-methyl pro-pane sulfonic acid(AMPS)、dimethyl diallyl ammonium chloride(DMDAAC) and itaconicacid(IA) were used as main monomers, and DAAI polymer was synthesized by free radicalsolvent polymerization. redox initiato (NH4)2S2O8and NaHSO3were used as initiator.Take the cement slurry water loss as a basis, optimum reaction conditions were definedby single factor analysis method and orthogonal test: reaction temperature was60℃, initiatoramount0.25%, total monomers concentration30%, monomer mass ratio m (AM):m (AMPS):m (DMDAAC):m (IA)=45:35:10:10, reaction time was5h. The product’s structure wasverified by infrared spectrum (IR) analysis. Thermogravimetric analysis (TG) indicated thatDAAI has excellent thermal stability. Study on the properties of polymer solution verified thatsynthesized fluid loss additive has good salt tolerance. Thus the fluid loss additive can workwell in phosphoaliuminate cement slurry system with high anti-salinity.The performance of phosphoaliuminate cement slurry system mixed with DAAI wasexamined. The results of experiments showed that the polymer can control water losseffectively and has good salt tolerance. The cement slurry system can keep good settlingstability after adding the fluid loss additive，which also has little influence on the compressivestrength of set cement. The cement slurry performed very well in its rheological property byadding dispersant. The fluid loss additive has subtle setting retarding effect on the cementslurry. Requirement of cement slurry setting time in different well depths can be satisfiedthrough regulating the amount of retarder.The viscosity measurement of cement slurry filtrate and observation of the configurationof slurry filter cakes by scanning electron microscopy (SEM) certified that filtrate viscosityincreases, yet which cannot present the reason for the good water retention capability of the DAAI copolymer, the main mechanism is forming dense cake by reducing filter cakepermeability.