Casing is cemented into the wellbore to provide zonal isolation of producing zones, protect fresh water zones from contamination, prevent casing collapse caused by moving salts or sloughing clays and isolate the casing from corrosive brines. In other words, casing is cemented to create annular isolation. Historically, the major physical property of the cement used to determine whether these results would be attained for the life of the well, was the unconfined compressive strength of the set cement.

Recent studies have shown that there are other "strengths or mechanical properties" that are even more important to consider. These strengths include tensile and flexural.

This paper discusses why tensile and flexural strengths must be considered in slurry design, alonf with the interrelationship of compressive, tensile and flexural stresses that occur in wells, and provides Appalachian Basin field examples, where reduced, unconfined compressive strength cement, with enhanced tensile and flexural strengths has been successfully used.

You can access this article if you purchase or spend a download.