| In the process of deep complex reservoir oil and gas exploration and development,the lubricity of the drilling fluid is an important factor affecting the integrity of the oil and gas well,drilling safety and efficiency.The increase of complex geological conditions such as high temperatures and high salt often lead to increased friction,increased torque and lubrication failure.Therefore,the design and development of drilling fluid lubrication system with high temperature resistance,salt resistance and efficiency is an important way to ensure safe,efficient and stable drilling under complex reservoir conditions.In this paper,three series of montmorillonite(MMT)intermediates with different interlayer microenvironment and surface characteristics are created.Nanocomposite microsphere anti-wear agents with the nano-uniformly dispersed MMT intermediate layer are prepared by designing the in-situ polymerization reaction.A new polymer/montmorillonite nano-composite microsphere emulsion lubricant is obtained,and the lubricating drilling fluid systems with high temperature resistance,salt resistance and lubrication are also produced.The specific research findings and results are as follows:(1)The mono-modified MMT intermediate(OMMT)is designed and prepared by using a preferred anionic MMT modifier.The polystyrene/OMMT(PS/OMMT)nanocomposite microsphere antiwear agents are prepared by in-situ emulsion polymerization of the intermediate,and then the nano-composite microspheres emulsion lubricants are obtained by mixing methyl silicone oil and PS/OMMT.The effect of OMMT content on the micro-morphology and structural properties of polymer nanocomposite microspheres is investigated.As for the nano-nucleation center,the OMMT layers can reduce the particle size and increase the monodispersity of the nanocomposite microspheres.The results of transmission electron microscope(TEM)and scanning electron microscope(SEM)show that the monolayer of MMT is adsorbed on the surface of the microspheres and/or embedded inside the microspheres to control the surface smoothness of the microspheres.The results of thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC)show that the OMMT is used to delay the thermal decomposition rate of the polymer matrix and improve the glass transition temperature.The relationship between lubrication of the nano-composite microsphere lubricant and the addition of OMMT is established by tribological experiments.(2)Two binary modified MMT intermediates(P-SLS-MMT and P-KH570-MMT)are prepared by using the quaternary phosphonium cation modified montmorillonite(P-MMT),sodium dodecyl sulfate(SLS)and 3-methacryloxypropyltrimethoxysilane(KH570).The relationship between the modification method and the microstructure and physical and chemical properties of MMT is studied by infrared spectroscopy,TEM and TGA techniques.Three kinds of poly(styrene-methacrylic acid)(P(S-M))nanocomposite copolymer microsphere antiwear agents filled with modified MMT are prepared by using the in-situ soap-free emulsion polymerization.The effects of different types of MMT on the apparent morphology and structural properties of copolymer microspheres are investigated.The results of TEM and X-ray diffraction(XRD)show that the uniformly dispersed and highly exfoliated modified MMT layers are fully and/or partly coated in the copolymer microspheres.The results of dynamic light scattering(DLS)and SEM show that the modified MMT layers can control the particle size reduction,increase the monodispersity of the copolymer microspheres and improve the surface fullness smoothness.The thermal decomposition properties of the copolymerized microsphere antiwear agent are significantly improved due to the addition of montmorillonite.The relationship between the series nanocomposite copolymer microsphere emulsion and the antiwear and antifriction properties of PAO base oil is established,and the binary modified MMT nanocomposite microsphere emulsion lubrication system with the lubrication and antifriction properties is optimized.(3)The relationship between modification method of the MMT and the MMT structure is established,and the ternary modified MMT intermediates are prepared.The effects of sequence and combination of different modification methods on the microenvironment and surface properties of MMT interlayer are studied.The polymethylmethacrylate(PMMA)/ternary modified MMT nanocomposite microsphere antiwear agents are successfully prepared by using the in-situ soap-free emulsion polymerization mediated by ?-cyclodextrin.The relationship between MMT addition and micro-morphology and structural properties of nanocomposite microspheres is established.It is found by TGA analysis that the heat resistance of the nanocomposite microsphere anti-wear agent decreased with the increase of the amount of ternary modified MMT.Four-ball friction and wear test established the relationship between polymer/ternary modified MMT microsphere emulsion and vegetable base oil in the lubrication anti-wear and anti-friction effect.(4)According to the characteristics of three series of polymer/montmorillonite nanocomposite emulsion drilling fluid lubricants,the relationship between the different type and addition of the lubricant and the drilling fluid base slurry rheology,API fluid loss,density change,temperature resistance and salt resistance are established.The results of extreme pressure lubrication test indicate that the modified MMT types and their loadings have important influence on the lubrication and drag reduction of the nanocomposite drilling fluid lubricant and their drilling fluid physical and chemical properties.The optimized nanocomposite lubricants for drilling fluids with the best lubrication coefficient of 0.09,lubrication coefficient reduction rate of over 83%temperature resistance of 180-220 ?,high salt resistance and high efficiency of drag reduction performance.Such lubrication drillin fluids have really practical applications.The polymer/montmorillonite nanocomposite microsphere lubricating material prepared in this paper provides a new lubrication and drag reduction candidate material for drilling fluids for safe and efficient drilling under complex conditions such as high temperature and high salt in deep and complex reservoir oil and gas wells. |
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