A Study On The Strength And Acoustic Characteristics Of The High Density Cement Stone Under The Condition Of High Temperature

In well cementation may encounter abnormal high pressure gas,high pressure brine zone and high temperature and high pressure formation,in order to stabilize formation,high tempe rature and high density cement slurry system is often used.And high density cement slurry sy stem due to its different admixtures and complicated HTHP environment,its microstructures a nd crystal composition and stability of the slurry will be changed,if at this time still in the nor mal density of the acoustic characteristics of the cement reaction for the standard used to eval uate the cementing quality of high density cement,obviously,it will not be accurate.Therefor e in this paper,the high density of cement strength and acoustic characteristics are studied,an d put forward the high density cementing quality evaluation criterion of suggestions for impro vement.We study the iron powder density cement,magnet powder density cement and manganes e powder slurry density of high density cement slurry system,curing temperature,cement sto ne compressive strength,the relationship between the sound velocity and acoustic impedance factor through laboratory experiments.The study show that,iron powder high density cement,magnetic powder high density cement and manganese powder high density cement slurry sys tem of compressive strength and the sound velocity is linear negative relationship with cement slurry density;the sound velocity of cement and acoustic impedance of the cement are the res ult of comprehensive factors,and it also has a relationship with the type of fillers,water ceme nt ratio,curing temperature,etc,not only with a certain correlation factor;The cement stone h as good linear relationship between compressive strength and acoustic impedance for iron and manganese powder high density cement slurry system,and it has good quadratic term relation ship for magnet powder high density cement slurry system.At the same time,further study o n the hydration products of Portland cement under the condition of high temperature,reveals t he acoustic wave propagation under different temperature change rule of the internal mechani sm.High density cement with conventional density cement on the acoustic properties of difference makes the conventional density cement cementing quality evaluation standard is not suitable for high density cement cementing quality evaluation,so it needs to introduce a amplitude decrease coefficient to be corrected.We work out the relationship between the high density cement acoustic amplitude decrease coefficient ? and cement acoustic impedance by theoretical analysis and experimental research of the combination of acoustics,and analyze the influence factors of high density cement acoustic amplitude decrease coefficient ?,then put forward the high density cementing quality evaluation criterion of suggestions for improvement.