关键词: 非均匀, 载荷, 套管应力, 强度, 泥岩, 蠕变

Abstract: Calculation methods of casing stress and strength under nonuniform loading distributed as ellipse induced by mudstone creep are derived on the basis of establishing nonuniform outside loading models for mudstone creep.On the condition of nonuniform loading, maximum loading that the casing can bear is reduced rapidly.When inner-pressure is 0.1MPa, critical loading of the casing is about 11 percent, on the uniformed of loading condition averagely.Analysis of the casing deformation at mudstone formation in Daqing Yushulin oil field showed that the flooding water with high pressure entered into mudstone formations along vertical fractures caused the mudstone formation to absorb water to creep, and made J-55 casing difficult to bear larger nonuniform squeezing pressure and leaded to casing deformation.To ensure the safety of the wellbore, it is proposed that P-110 casing is used in the section which the mudstone creep is easily occured.

Key words: nonuniform, loading, casing stress, strength, mudstone, creep