As the world's traditional oil and gas reserves decline, the industry is challenged to produce from unconventional sources. Heavy oil is found in different parts of the world and could be an answer to the demand for energy. However, heavy oil is highly viscous and traditional methods are not sufficient to produce these wells.

One option is to inject fluid such as steam to decrease the viscosity, making it feasible to produce the heavy-oil reserves. However, the steam heats the casing and the cement sheath in addition to the reservoir of heavy oil. The increase in temperature is high and imposes considerable thermal stress on the casing and the cement sheath. In many wells, the upperhole section is unconsolidated, posing higher risk to the cement sheath when subjected to stresses.

If the cement sheath is unable to withstand the stresses, it could be damaged and fail to provide zonal isolation. The cracks and microannulus in the cement sheath can act as a pathway for the steam to escape. This could considerably reduce the recovery of heavy oil while posing health, safety, and environmental challenges.

The design procedures necessary for evaluating the properties needed in the cement sheath to help withstand thermal stresses are discussed in this paper. Procedures to improve cement slurry placement are also presented. Additionally, methods to reduce heat losses in the upperhole section as well as reduce temperature stresses while optimizing the overall well-construction for heavy-oil recovery are also discussed.

This work should aid in the construction of wells that will contain injected fluids such as steam in the recovery of heavy oil. The cementing procedures discussed in this paper should help improve heavy-oil recovery as well as health, safety, and the environment.

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