Effect Of Low Temperature Plasma Modified Rock Asphalt On Mechanical Properties Of Oil Well Cement Stone

Due to the problems of brittle fracture and poor impact resistance of the oil well cement ring,this paper intends to add rock asphalt particles that with viscoelastic into oil well cement slurry to improve the mechanical properties of oil well cement paste.However,rock asphalt is a hydrophobic material that is difficult to disperse in the well cement slurry,and its effect on the performance of the oil well cement paste varies with temperature.Therefore,in this paper,the low temperature plasma technology are used to improve the hydrophobicity of the surface of the rock asphalt particles,and then to explore the influence of modified rock asphalt on the mechanical properties of the oil well cement paste at different curing temperatures.Infrared spectroscopy and contact angle test is carried to investigate the effects of plasma treatment time,plasma treatment power and gas flow rate on the surface groups and wettability of rock asphalt particles before and after modification by low temperature plasma.Then the effect of 0%?4%modified rock asphalt on the performance of oil slurry is studied.Then,the influence of modified rock asphalt on the mechanical strength of oil well cement paste is studied under different curing temperatures(30?,60? and 90?).The influence of low temperature plasma modified rock asphalt on the deformation ability of oil well cement paste is studied by testing the changes of Young's modulus and Poisson's ratio at 30?,60?and 90 ? of pure oil well cement paste and oil well cement paste which mixed with 4%modified rock asphalt.The influence of low temperature plasma modified rock asphalt on hydration of oil well cement is studied by X-ray diffraction,infrared spectroscopy and TG analysis of sample pure oil well cement paste and oil well cement paste which mixed with 4%modified rock asphalt.Scanning electron microscope is used to observe the interfacial adhesion between rock asphalt particles and oil well cement hydration product,and the effect of modified rock asphalt on crack development.The modified results show that:The sulfonic acid groups(-SO3H)formed on the surface of the rock asphalt after the low temperature plasma modification make the hydrophobicity of the rock asphalt improved obviously.When the treatment time,treatment power and oxygen gas flow rate are 3 minutes,100W and 40Sccm,the effect of modification is better,and the contact angle between rock asphalt and water decreases from 107° to 32.48°.The effect of modified rock asphalt on the compressive strength of oil well cement paste show that:The addition of low temperature plasma modified rock asphalt reduces the compressive strength of cement paste.When the curing time is 28 days,the compressive strength of the oil well cement paste with 4%modified rock asphalt cured at 30?,60? and 90? are 11.65%,12.35%and 13.69%lower than that of pure oil well cement paste respectively.The effect of modified rock asphalt on the tensile strength of oil well cement paste show that:The effect of modified rock asphalt on the tensile strength of oil wells cement paste change with the change of temperature.When the curing time is 28 days,the tensile strength of the oil well cement paste with 4%modified rock asphalt cured at 30? and 60? are 26.3%and 24.8%lower than that of pure oil well cement paste respectively.When the curing time is 28 days,the tensile strength of the oil well cement paste with 4%modified rock asphalt cured at 90? is 31.1%higher than that of pure cement paste.The effect of modified rock asphalt on the deformation ability of oil well cement paste show that:The effect of modified rock asphalt on the deformation ability of oil wells cement paste change with the change of temperature.When the curing time is 7 days,the Poisson ratio of the oil well cement paste with 4%modified rock asphalt cured at 30? and 60? are 7.69%and 3.73%lower than that of pure oil well cement paste respectively,the young's modulus are 10%and 8%higher than that of pure oil well cement paste respectively.But,when the curing temperature is 90?,the 7-day Poisson ratio of the oil well cement paste with 4%modified rock asphalt is 7.14%higher than that of pure cement paste,the 7-day young's modulus was 7.3%lower than that of pure cement paste.The effect of modified rock asphalt on the hydration degree of oil well cement paste show that:The addition of modified rock asphalt retards the hydration of oil well cement.Microstructure analysis shows that:Cement hydration products and low temperature plasma modified rock asphalt particles have good cementation.The addition of modified rock asphalt at 30? and 60?is not conducive to improving the deformation ability of oil well cement paste.At 90?,the addition of modified rock asphalt can improve the deformation ability of oil well cement paste.