- 期刊
儲氣田氣井套管水泥之應力分析
Stress Analysis of the Casing Cement in the Reservoir Gas Well
摘要
本研究利用數值軟體ANSYS，對油氣井套管水泥進行應力分析，探討水泥段的破壞模式。並對不同配比的水泥進行試驗，求得其基本力學參數，代入數值分析中探討各種加載下適用的水泥參數。研究結果指出，套管水泥封固能力的喪失與水泥和岩石的力學參數、異質材料界面結合強度及所受的加載方式有相當的關連。井壓增加時，高楊氏模數的岩石可幫助水泥抵抗破壞；水泥段外部壓力增加時，高楊氏模數的水泥較能抵抗破壞；井溫增加時，低楊氏模數的水泥較能抵抗熱應力作用之破壞。套管水泥的疲勞破壞方面，研究結果指出在週期性壓力加載下，當井壓由10MPa增加到20MPa，疲勞壽命會大幅地降低，當井壓大到70MPa時，疲勞壽命小於300次。
並列摘要
This study used a finite element analysis package, ANSYS, to analyze the mechanical behaviour of the casing-cement system and discuss the failure mode of the cement portion. This study also carried out experiments for three kinds of cements to obtain their mechanical parameters. The experimental results were incorporated into the numerical analysis and the proper cement mechanical properties were discussed. The results indicate that the loss of cement bond log is related to the types of applied load and mechanical properties of the cement and rock. When wellbore pressure increases, high Young's modulus rock can help cement to resist fracture. When outer cement stress increases, high Young's modulus cements are advantageous. However, when wellbore temperature increases, low Young's modulus cements are preferred. Under periodical wellbore pressure loads, the casing cement will show fatigue failure. The results show that when wellbore pressure increases from 10MPa to 20MPa, the fatigue life of the casing cement will decrease greatly. When the wellbore pressure increases to 70MPa, the fatigue life of the casing cement is less than 300 cycles.