注汽井套管系统热-结构耦合场有限元研究

FINITE ELEMENT METHOD OF CASING SYSTEM THERMAL-STRUCTURE COUPLING FIELD IN STEAM INJECTOR

对注汽井套管的失效机理和原因进行分析,归纳总结了影响失效的因素,理论分析了注汽井套管和水泥环之间的变形协调关系,利用ANSYS参数化设计语言,开发了套管、水泥环和岩层系统的热-结构耦合的二维平面有限元分析命令流,并研究了参数变化对热-结构耦合的套管强度的影响。分析结果表明:在小于14 mm之前套管壁厚增加会明显降低套管最大峰值应力,此后套管壁厚增加套管最大峰值应力下降速度会减缓。仅从热膨胀角度来看,套管最大峰值应力随蒸汽温度增加而增加。310℃以后套管最大峰值应力随蒸汽温度增加会加剧。

This research analyzed the failure mechanism and causes of the casing damage in steam injector and summarizes the factors of casing failure,also,the compatibility conditions of deformation between the casing and cement hoop in steam injector is analyzed,then the ANSYS Parametric Design Language is applied to develop the order flow procedures of the two-dimension plane finite element which is applied in thermal-structure coupling condition for casing,cement hoop and rock.At last,the influence of the parameters change on casing strength in thermal-structure coupling condition is studied.The result shows that when it is less than 14mm,the maximum equivalent stress will decrease evidently as the increase of thickness of casing,and when it is more than 14mm,the decrease of the maximum equivalent stress rate will be mitigated.From the viewpoint of thermal expansion,the maximum equivalent casing stress will increase when the stream temperature increases.When the stream temperature is more than 310℃,the maximum equivalent casing stress increases sharply.