The safe operation of geothermal wells is usually achieved with a two-barrier philosophy, similar to that used in oil and gas wells, where production tubing and/or casing constitute the primary barrier to production loads, with the wellbore cement representing the second integrity-assuring element. Well cement plays an important role in providing well integrity, yet also influences wellbore heat transfer, but its mechanical and thermal properties can vary significantly depending on the mixing method employed, the slurry composition, curing conditions, and human factors. Mechanical strength still represents the major criterion for cement selection, although thermal properties of cements represent an important parameter in the efficient design of geothermal wells. This paper focuses on the effects of remedial cementing on wellbore integrity and heat transfer, considering how the chosen method of remediation may result in different degrees of efficiency. From experiments designed to reproduce such remedial actions, cement properties are assessed and used to quantify the effect of these procedures on the overall heat transfer in the wellbore, in regards to both thermal stresses and heat exchange. Testing shows that cement mixing with annular fluid during the remedial phase will lead to changes in cement heat transfer properties and may increase the localized wellbore stresses.

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