Study On Influencing Factors And Action Law Of Mechanical Properties Of Cement Stone

As the sealing material for the annular space between the casing and the stratum,the oil well cement slurry is essential for the mechanical properties after solidification.It is an important basis for the optimization and formulation optimization of the cement slurry.It is the research,testing and evaluation of the integrity of the cement ring.Important input parameters,for this reason,it is accurate to detect and conform to the actual situation of the well.It has important practical significance for whether the mechanical properties of cement stone can meet the needs of long-term interlayer sealing of the sealing section.In the past,the mechanical properties of cementing cement stone have a set of commonly used processes,but at room temperature or medium temperature plus atmospheric pressure/high temperature plus high pressure curing,demoulding under normal temperature and normal pressure,reheating and pressure rising or room temperature and atmospheric pressure detection,During the maintenance-testing process,when the temperature and pressure are greatly changed,the cement slurry(stone)is subjected to temperature and pressure changes in the well,but the variation is much smaller.However,the cement stone with obvious brittle characteristics,regardless of temperature and pressure changes.The amplitude and the speed of temperature and pressure change may lead to changes in its microstructure and macroscopic properties,which may lead to the deviation of the test results from the actual underground conditions,which in turn leads to the preferred cement slurry system and optimized cement slurry formulation deviating from the actual needs of the well.The cement ring integrity research,test and evaluation results with this input parameter will also deviate from the actual situation.In order to grasp the influence of relevant factors on the test results of cement stone mechanical properties,the method and device for testing the mechanical properties of cement stone which are more in line with the actual conditions are established.this paper carries out research and obtains the following new understandings:(1)By comparing the fluctuation amplitude and coefficient of variation of the test results,the effects of square,medium and small circular die with different shape and size on the mechanical properties of cement stone were studied.The results show that the small die in three molds The test results of the obtained test pieces are more stable and reliable.(2)By analyzing the results of XRD,thermogravimetry and nitrogen adsorption pore distribution of cement stone obtained by different temperature and pressure curing,the influence of cement slurry curing temperature on the mechanical properties of cement stone was studied.The results show that curing temperature can significantly affect The cement stone composition and internal microstructure formed by the cement slurry,which in turn affects the mechanical properties of the cement stone.(3)By analyzing the difference of mechanical properties of cement stone after solidification and then undergoing different temperature and pressure changes(history),the influence of the change between curing temperature and temperature on the mechanical properties of cement stone was studied.The results show that The change of temperature and pressure can significantly affect the test results of mechanical properties of cement stone,and the greater the magnitude and speed of temperature and pressure change,the more large pores inside the cement stone and the worse the test results;therefore,the maintenance must be fully considered-The effect of temperature and pressure changes on the test results during the test.(4)By analyzing the test results of mechanical properties of cement stone undergoing the same maintenance-test temperature and pressure change,the effects of conventional triaxial and ultrasonic testing methods on the test results were studied.The results show that the difference of the surrounding rock by the simulated surrounding rock is different.The detection results of the two methods can be closer to the actual situation when the pressure in the casing is small and large.The research results in this paper have studied and confirmed the significant influence of temperature-pressure change between curing and testing on the mechanical properties of cement stone,further enriching the understanding and understanding of how to accurately detect the mechanical properties of cement stone in underground temperature and pressure environment.It also lays a certain theoretical foundation and technical guidance for the study of the method and device for testing the mechanical properties of cement stone which is more in line with the actual situation.