蠕变地层套管损坏的主要原因是套管外壁受到蠕变地层的非均匀载荷作用,套管本体抵抗非均匀载荷能力远远低于套管抗挤强度而产生缩径变形。通过分析蠕变地层套管非均匀载荷的分布形式,并考虑在该非均匀载荷作用下套管的强度特征及固井水泥环力学性能对套管抗非均匀载荷影响的基础上,采用有限单元法,分析了蠕变地层套管本体、固井套管组合体的等效破坏载荷。结果表明,非均匀载荷作用下套管的抗载能力迅速下降,提高固井水泥性能,切实保证固井质量将显著提高套管抵抗非均匀载荷的能力。
The situation of casing collapse is serious in creep formations, and the mainly reason is the nonuniform loading distributed. The equivalent collapse resistance that the casing can bear under nonuniform loading is much less than the collapse resistance under the condition of uniform loading, it is difficult for casing to resist larger nonuniform squeezing pressure and the casing deformation or casing collapse will occur. For studying the equivalent collapse resistance of casing under nonuniform loading, it is necessary to discuss the loading distributed form, the intensity characters of casing and the effect of cement The equivalent collapse resistances of casing and the system of casing-cement were analyzed by finite element method. The analysis results indicate that the equivalent collapse resistance falls down rapidly. In order to improve the equivalent collapse resistance of casing, enhancing cement capability and improving cement job quality should be done.