Analysis of casing equivalent collapse resistance in creep formations

Key words:  creep formation  casing collapse  nonuniform loading  equivalent collapse resistance

Abstract:

The situation of casing collapse is serious in creep formations, and the mainly reason is the nonunifonn 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.