Synthesis And Performance Research Of New Latex Additive For Well Cementing

Oil well cement admixtures,such as retarder,toughener and fluid loss additive,are generally single in the function.During the cementing operation,they are used with other additives together in most cases.This situation not only increases the cementing costs,but also may cause construction safety problem with bad compatibility.Thus,it is urgent to develop a kind of admixture with comprehensive performance for solving this problem.Based on the extensive investigation of latex additive in literature and patent,oil well cement latex additive(FTL)with function of toughening,week retarder and control water loss,is synthesized by seed emulsion grafting polymerization,using polybutadiene latex as the main chain,styrene,2-acrylamido-2-methyl propane sulfonate(AMPS)and N,N-dimethylacrylamide(DMAA)as grafting monomers.Molecule structure of the latex is characterized by using Fourier Transform Infrared Spectroscopy(FTIR)and the result shows that FTL achieves the desired design goals.Temperature resistance of the latex is characterized by using Thermogravimetric analysis(TG)and low temperature freezing method and the results show that the FTL has good temperature adaptability.Salt resistance property of the latex is also investigated and the result shows that the FTL has better saturated brine resistance stability.Free water,salt resistence,mobility and thickening performance of latex cement slurries are evaluated.The results demonstrate that cement slurries with FTL have properties of low free liquid,salt-resistance,better mobility and good thickening performance.The setting time,water fluid loss and flexural strength of latex cement stone are discussed and the results show that FTL has multi-effect function with toughening,week retarder and control water loss.This article investigates the influencing factors for the performances of latex cement and obtains the optimal monomer ratio and latex dosage.The toughening,week retarder and control water loss mechanism of cement with FTL are explored by Scanning Electron Microscope(SEM),X Ray Diffraction(XRD),Differential Scanning Calorimetry(DSC)and FTIR and the results find that polymer membranes are formed on the surface of cement hydration products by latex particles and the presence of latex only hinders the early hydration of cement,but not changesthe final hydration process.