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As a tertiary oil recovery technology, CO 2 injection is a promising method to rejuvenate the oil reservoirs after the primary production. However, with the injection of low-temperature liquid CO 2 into deep geological structures for the purpose of CO 2 storage and/or enhanced oil recovery (CO 2 -EOR), some of the injection wells experienced problems with tubing and casing failures. The objective of this paper is to find the root cause of tubing and casing failures. The thermo-mechanical coupling numerical simulation model and laboratory experiments are conducted to investigate the effect of frost heaving on tubing and casing. The simulation results well agree with those experimental data, which implies the numerical model is valid and can describe the thermo-mechanical process in the CO 2 injection well. Then, the effect of tubing coupling, annulus width, thickness and operation pressure are explained and analyzed by combining the production parameters and numerical simulation. The results indicate that: (a) The frost heaving generated by volume expansion with freezing of annulus liquid during the low-temperature CO 2 injection is the root cause of tubing and casing failures. (b) The decrease of annulus width and increase of thickness will lead to a dramatically decrease of tubing and casing stress. (c) Increase tubing pressure can help to reduce the tubing stress. Finally, based on the failure mechanism and frost heaving characteristics, an optimal tubing-casing combination is proposed to prolong the operation life of tubing and casing. • Frost heaving pressure is the root cause of tubing and casing failures. • Effect of different structural and operational parameters on frost heaving characteristic are analyzed. • Decreasing annulus width, increasing tubing thickness and pressure are effective measures to reduce frost heaving effects. • An optimal tubing-casing combination is obtained. [ABSTRACT FROM AUTHOR]

Carbon dioxide injection or storage in mature or partially depleted oil reservoirs is an effective way to reduce carbon dioxide emissions and improve oil recovery. However, the corrosion defects greatly reduce the residual mechanical strength of the tubing with the effect of frost heaving force, which seriously limits the carbon dioxide enhanced oil recovery technology widely application. Therefore, the residual mechanical strength of corroded tubing in cryogenic carbon dioxide injection well is investigated in this paper. The results indicate that: (a) The residual mechanical strength of corroded tubing with the effect of frost heaving force is about 68% less than that without frost heaving force. (b) The effect of corrosion depth and location are sensitive, while the corrosion shape is relatively weak. (c) It is a meaningful method to increase working pressure to improve the residual mechanical strength of corroded tubing in the frozen section. • Frost heaving force reduces the strength of the tubing by about 68%. • Corrosion depth and location are more sensitive than corrosion shape. • Increasing working pressure is conducive to improve the residual mechanical strength. [ABSTRACT FROM AUTHOR]