Nonuniform loading affects casing collapse resistance.

The article presents the latest developments in the study on the effects of casing imperfections and nonuniform loading conditions to the collapse resistance of well casing used in the oil and gas industry. It cites the new equations that were developed by the China-based Southwest Petroleum Institute to estimate the collapse resistance pressure for casing under variable loading conditions. The equations were partly based on the theory of elasticity and plasticity.