Proper well construction involves long-term integrity; thus, accurate characterization of the physical properties of set cement systems is mandatory. Chemical stability, compressive strength, and permeability are commonly the main parameters determined for oilfield cement systems. The knowledge of these properties is most often enough to estimate if a cement system will maintain well integrity. However, some hydrocarbon recovery processes are highly aggressive toward the cement sheath. Under thermal processes for recovery of heavy oil, such as steam-assisted gravity drainage (SAGD) or cyclic steam stimulation (CSS), the well temperature can reach up to 350°C. The casing expands during the heating-up phase, and this outward expansion increases the stress on the annular cement sheath. Under such conditions, simulations show that a key intrinsic thermal property, the linear coefficient of thermal expansion (LCTE), is equally as important as the other physical properties to maintain well integrity.

To determine the LCTE of set cement, one needs to understand the thermal-expansion theory of solid materials. An experimental setup for measuring this parameter for set cement has been developed, and essential precautions for performing accurate measurements have been formulated.

The LCTE of cement is a critical parameter in the development of new cement technologies for high-temperature (HT) well applications; the chemical composition of the cement system and the curing conditions can affect the LCTE of oilfield cement systems.

Improved understanding of this critical parameter has allowed significant improvement of the reliability of cement systems used in these hostile environments and provides better solutions in the form of thermally responsive cement systems.

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