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Thermal technologies are widely used for the heavy oil recovery. The thermal processes usually consist of some variation of Cyclic Steam Stimulation (CSS), steam flood or Steam Assisted Gravity Drainage (SAGD). These thermal recovery applications have experienced numerous well casing failures around the world, often resulting in loss of wellbore integrity, lost production and added costs. The primary casing failure mechanisms include casing connection leakage and/or parting due to excessive casing strain and wellbore serviceability difficulties due to large casing deformation associated with casing buckling and shear. Due to high operation temperatures (e.g. 220 to 350°C), casing deformations often exceed the elastic limit of typical thermal well casing materials. Therefore, a strain-based design concept and advanced finite element analysis are often used to consider the allowable casing strain capacity beyond yield and the associated non-linear material and structural responses. This paper presents analysis models, developed using Abaqus, for analyzing casing deformations resulting from thermal loading, buckling and formation shear movement. It is demonstrated that the analysis results of casing deformations can constitute a more advanced and sound basis for thermal well casing designs which minimize the potential for thermal wellbore casing failures.
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