Preparation And Performance Study Of A Star-shaped Emulsifier For Oil-based Drilling Fluid

Employing four main materials:triethanolamine,thionylchloride,dodecylbenzene and chlorosulfonic acid,the thesis synthesized a star-shaped sulfonate emulsifier via three steps,including chlorination reaction,alkylation reaction and sulfonation reaction.Then synthesis condition of the star-shaped emulsifier for oil-based drilling fluid was optimized through orthogonal test.First of all,interface performance of the star-shaped emulsifier was studied.Critical micelle concentration of star-shaped emulsifier was 5.53 × 10-5 mol/L through interface tension test.And its dynamic interface tension showed star-shaped emulsifier could be rapidly adsorbed on the oil-water interface,and significantly reduced the oil-water interfacial tension.At the same time,interfacial dilational modulus of the oil-water interface indicated the oil-water interface had high viscoelasticity and could form high-strength interface film to keep the stability of the emulsion.Second,through the dilution method and filter paper wetting,the star-shaped emulsifier was identified as a hydrophilic emulsifier which could form a stable water-in-oil emulsion.After star-shaped emulsion was prepared,its stability was evaluated through methods such as demulsification voltage method and emulsification rate method.When adding 2.0%emulsifier,demulsification voltage of the emulsion was higher than 400V.So it can satisfy the requirement of emulsifier for oil-based drilling fluid.Emulsion has relatively high emulsion stability before and after the aging period.Later,emulsion particle size and distribution were tested by microscope and laser particle size analysis,It's found that the water drops in emulsion had uniform distribution and very low average particle size.When adding 2.0%emulsifier,the average particle size was less than 5um.Finally,the star-shaped emulsifier was added into oil-based drilling fluid to analyze rheological property,temperature resistance and fluid loss of the drilling fluid system.Results showed drilling fluid system had good rheology,low filtration volume.Its temperature resistance could reach 180 ?.Also,the system has strong pollution resistance which could resist 15%drilling cuttings pollution and 10%water pollution.