Force Analysis Of Casing And Cement Ring In Oil Shale Thermal Recovery Well

Today,the development of industry has brought about an increase in global energy consumption,and conventional oil production has been restricted.Therefore,in recent years,unconventional oil and gas and oil shale mining have become hot spots for energy development.When oil shale is exploited,a large amount of high-temperature steam needs to be injected through the pipeline,and the casing-cement ring-stratigraphic system will generate large thermal stress,which will cause the casing to yield and the cement ring to be destroyed.Based on the previous research,this paper addresses issues that may arise in the exploitation of oil shale and introduces problems from the theoretical point of view.Taking the change in the elastic modulus of steel materials and the three-dimensional detackification model as innovation points,the numerical simulation The casing-cement ring-stratigraphic system is analyzed.The main tasks are as follows:1 Based on the theories of heat transfer and elasticity,and the Mises yield strength theory,a theoretical background is introduced for the casing-cement ring-stratum model.(1)From the basic theory of heat transfer,make relevant assumptions and introduce the theories involved in the heat transfer process of the casing-cement ring-stratum system.(2)From the viewpoint of elasticity,reasonable assumptions are made for the casing-cement ring-stratigraphic system,and the deformation equations during the heating process are introduced.2 Find the relevant engineering data and determine the parameters of each part of the system so that the simulation parameters are close to the actual project conditions.(1)Finding the steel standard,coMParing all common types of steel,according to the elastic modulus and the relationship between yield strength and temperature,select the most suitable steel type P110.(2)Search for changes in temperature and depth of the formation,and other parameters.3 The simulation analysis of the system under the two-dimensional model,through the two-dimensional model of the system,analyzes the stress distribution and deformation of the system.(1)By coMParing the simulation results with the experimental results,the credibility of the simulation model under two-dimensional conditions is determined,and the error between the simulation results and the experimental results is about 5%.(2)In case of different casing eccentricity,the influence of the eccentricity change on the maximum stress of the casing and the cement is almost negligible,but it has influence on the stress distribution area of the cement.(3)Under different cement parameters,the lack of cement ring has little effect on the maximum and minimum radial stress,but it affects the distribution area of ??the maximum radial stress.The increase of the elastic modulus of cement will lead to an increase in the radial stress of the cement ring.(4)Under different stratigraphic parameters,the results show that the nature of the poor strata and the consequences are that the radial stress of the cement ring is greatly increased and the radial stress exceeds the compressive strength.(5)Under the different comprehensive conditions,the worse the working conditions,resulting in easy to damage the casing.4 Simulation analysis of the system under three-dimensional model: The system is modeled in three dimensions,and based on the property of mutual contact,the debonding conditions of casing and cement under different temperatures are analyzed.(1)Analyze the debonding conditions of casing and cement under different thermal expansion coefficients.The results show that the higher coefficient of thermalexpansion of steel will increase the debonding of casing cement.At the same time,the lowest temperature is 150?.100% detackification of pipe cement occurs.(2)Analyze the debonding conditions of casing and cement under different cementation strengths.The results show that lower cementation strength will lead to easier debonding of casing cement,and lower cementation strength will also lead to casing.Detackification is more likely to occur between cements.The simulation results show that the selection of high-strength steel,good cement and strengthening of the cement injection process can reduce the stress of the system to a certain extent.In the design of the actual thermal recovery well,it is also necessary to consider changes in the depth of the formation along the ground,which is poor.The characteristics of the formation can cause the system to be easily destroyed.At the same time,if the temperature is kept below 150?,the system is relatively safe and is not easily damaged.Through the above simulation study,it provides some suggestions for how casing-cement ring-stratigraphic system can maintain stability under high temperature conditions.