Synthesis And Properties Of Latex Flexibilizer For Oil Well Cement

Recently,The better flexibility and the interface cementation strength are needed when well bore structures and the geological conditions are increasingly complex or changeful,Less flexibility,lower interface cementation strength,poorer fracture resistance often lead to oil-gas-water channeling,especially in deep well,ultra-deep well.During the exploitation process,some measures,such as Perforation,fracturing and acidizing,can bring micro-cracks and brittle fracture to cement stone under the impact stress.As a result,the interfaces between cement stone and drive pipe or side wall would be damaged to cause fluid channeling and seriously affect the cementing quality.Thus,Latex flexibilizer is needed to add to slurry to improve the temperature-resistance,salt-tolerance,flexibility and the cementation strength of the cement stone.In this paper,Styrene-butadiene latex named CSL-100 L possessing emulsion stability,was synthesized using the monomers of styrene(St),liquid polybutadiene(LPB)and 2-acrylamido-2-methyl-propane sulfonic acid(AMPS)via seeded emulsion polymerization.The latex with CSL-100 L was used as a flexibilizer for oil-gas cement.Physical properties indicated that,CSL-100 L has better mechanical stability and chemical stability in comparison with commercial DRT-100 L,which has good market value.IR shown that,TG analysis indicated that,the polymer with the structure of all the monomers is the target product.It was demonstrated by TG and TEM analysis that the CSL-100 L possessing stable molecular structure in 370?has an excellent thermal stability.And the diameter of CSL-100 L with core-shell structure is about 80 nm.According to the GB/T 19139-2003,The regular properties of the slurry,salt resistance,anti-gas channeling,thickening performance,mechanical properties and comprehensive performance of slurry with CSL-100 L were studied.Results shown that,slurry with CSL-100 L can effectively control the water loss in 50 ml when mixed with 3% fluid loss additive.Cement slurry with CSL-100 L has up to 15% to salt and can be used in salty cement slurry or sea water cement slurry.The slurry with CSL-100 L has quicker early strength development,shorter gelling strength transition time,"rectangular" thickening curves,less than 3 of SPN value and can has gas channeling prevention performance.Compared with DRT-100 L,elastic modulus of slurry with CSL-100 L was relatively lowered by 17.16% at the same concentration which can effectively improve the flexibility and deformation ability.The cement slurry prepared mainly by CSL-100 L presents good comprehensive properties such as wider applicable temperature,better rheological properties and the sedimentation stability,better compatibility with fluid loss additives and retarders,and so on.Moreover,Hydration reaction and microstructure of cement slurry with CSL-100 L were discussed by IR,SEM.To a certain extent,slurry with CSL-100 L may delay the hydration reaction of cement slurry.with the increase of the amount of CSL-100 L,Polymer film is more and more dense in order to improve the toughness of cement stone.