Rapid Calculation Method of Stress Analysis for Oil Well Casing

Oil well casing damage is a kind of catastrophic accidents in oilfield engineering site which may make the whole oil well abandoned. When the production casing is inserted into the intermediate casing, interaction occurs between them and possibly induces failure of the production casing. Because the casing is very long, mostly longer than 1 000 m, the calculation of the interaction is difficult. Some simplified methods are used in this paper to increase the calculation speed, including simplifying the intermediate casing as ana- lytical rigid body, reversing the production casing inserting process, simplifying the production casing as shell elements, cutting the inserting process into several steps, using the explicit method, increasing loading speed, artificially enlarging the mass, adding point mass on rigid casing. The calculation on the 1 000 m casing was done. And it was found that at the end of the production casing, the stress varied greatly; the stress along the diametrical direction varied greatly too. Fatigue damage could occur on the production casing.