Numerical Analysis of Casing Damage in Heavy Oil Thermal Recovery Wells

Abstract

With the decrease in the world’s thin oil resources, heavy oil resources gradually become the main resources in the current and coming period. However, the casing damage of thermal recovery wells seriously restricts the development and exploitation of heavy oil. By investigating geological conditions, production status, and casing damage from in Liaohe Oilfield, the mechanism of casing damage in heavy oil thermal recovery wells was analyzed. Through establishing a casing-cement sheath-formation model and using a thermosetting coupling model of transient heat transfer, the temperature field and stress field of casing in the perforation section were simulated and studied, and the influence law of thermal stress generated by high temperature on the casing was analyzed. The damage of perforated casing is mainly caused by thermal stress, making the casing bear the alternating load of high temperature and high pressure, research shows. After multiple rounds of steam huff and puff, the residual stress of casing increases with the period, resulting in casing fatigue failure. Meanwhile, sand production seriously abrades casing, causing stress concentration of casing and then accelerating casing damage. By studying the casing optimization design, the occurrence of casing damage in heavy oil thermal recovery wells can be reduced and even prevented.