A Research On High Temperature Oil Well Cement Fluid Loss Reducing Agent

In this paper,an oil cement filtration reducer called FR was obtained by the copolymerization of Acrylamide,Acrylic Acid and TS via free radical copolymerization.The polymerization conditions were optimized by the single factor method.The optimization of experimental conditions are as follows:the ratio of TS:AM:AA on mole is 1:0.5:0.5,monomer weight concentration is 20%of water,the initiator concentration(Ammonium persulfate)is 0.2%,the solution value pH is 5,reaction temperature is 70? and reaction time is up to 24h.Subsequently,the structure of the copolymer was characterized through Fourier transform infrared(FTIR)spectroscopy,proton nuclear magnetic resonance(1HNMR)spectroscopy.The results showed that all functional groups are present in the FR.Thermal gravimetric analysis demonstrated that the thermal stability of FR is excellent,which could be used at the high temperature of 440?.The experiment was conducted to study the effect of FR on comprehensive performance of oil well cement slurry.The result shows that the fluid loss can be controlled within 20mL when the dosage of FR is 1.0%of the total mass of cement and quartz powder under the ultra-high temperature condition of 200?.The FR is able to strengthen the viscosity of slurry and can also improve rheological property of oil well cement slurry in conjunction with the dispersing agent.The liquidity index n was 0.9 and viscosity coefficient K was 0.23Pa ·sn when FR dosage was 1.0%and the amount of dispersant SXY added was 0.5%.At high temperature,FR has less effect on the thickening time and it is capable of enhancing the cement strength,which ranges from 20MPa to 30MPa under the 90? aging condition.FR was applied to different brands of cement and different density slurry and it showed an excellent ability of controlling loss of water.The fluid loss can be controlled between 20mL and 50mL when FR dosage was 0.8%and 1.0%respectively.FR has the splendid property when used with a variety of oil well cement additives.By evaluating the relationship between the water loss and the absorbance?molecular weight as well as the shape of the FR,at the same time,SEM has been used to prove the theory.The result shows that as the absorbance of FR increased,the water loss decreased.The large molecular is easy to change the layer which covers on the cement and beneficial for turning into thick floor.As a result,the water loss could be controlled well.It is significant and crucial that-SO3H attached to the carbon atoms in the main chain for FR to resist higher temperature.The study reflect that the truth of FR could adsord onto the cement is the premise to control water loss.The theory of viscoelastic and adsorptive layer has been confirmed.