Mechanism Analysis Of Casing Deformation By Temperature And Stratum Coupling

With the deepening of the exploitation of oil and gas resources,the mining technology is becoming more and more complicated.The safety and integrity of the wellbore in the shale formation and the complex formation of the deep well have become the focus of our attention.The casing is an important part of the wellbore integrity,and its seal integrity is critical to oil and gas wells.Once the casing is damaged,it will seriously affect the exploitation of oil and gas resources and reduce the life of oil and gas wells.Based on this,the shale gas wells and high temperature deep well casing are affected by temperature and well Impact The following contents were studied:(1)The mechanics model of casing-confined water-rock assemblage with temperature stress is established.The law of shaft cooling and temperature transfer during shale gas well fracturing is analyzed.Under the specific temperature and pressure of fracturing process The three-phase state of the casing to determine the calculation of the different cooling under the ring closed water on the size of the casing outside the load.(2)The results show that the volume of the trap is reduced and the pressure decreases after the fracturing process.When the inside of the casing is cooled by 40 ?,the water pressure is lower than the gasification pressure,and the trap water vaporizes,and then the temperature decreases.The pressure of the casing is gradually reduced,the circumferential pressure of the casing is greatly increased,and the internal pressure of the casing is close to 1 when the inside temperature of the casing reaches 30 ?,Casing material force is also close to the yield stress,when the casing is located in the well when the slope,the strength will decline,then the safety factor will be less than 1,the assembly will be anti-internal pressure failure.(3)The failure mechanism of casing slip to casing is established,and the failure mechanism of casing slip is analyzed.The stress of casing and cement ring under different formation slip is calculated.At the same time,the different elasticity of cement ring The effect of modulus on casing force.The results show that the maximum stress of the cement ring and the casing is in the vicinity of the slip surface.The system force is proportional to the amount of the stratigraphic slip.When the strata slip reaches a certain level,the cement ring near the slip surface reaches the yield state,Reduce the elastic modulus of cement ring,casing force will have a certain degree of reduction.(4)The influence of temperature on the anti-crowding strength of high-temperature deep well casing is analyzed and analyzed.The characteristics of wellbore temperature change during cementing process are analyzed.The change of casing load caused by temperature change is calculated,and the external load The effect of casing on anti-crushing strength.Through the study of cementing displacement efficiency and mud cake erosion,slurry displacement theory is improved,which helps to improve the wellbore integrity and cementing quality.This study can provide reference for on-situ displacement efficiency and cementing quality prediction.