Testing and Evaluation Method Investigates Cement Expansion in Cased-Hole Wells
The authors describe a laboratory method for measuring cement expansion that has been used to evaluate the total bulk volume change of cement based on curing in a dry environment and in water.
Preventing bulk shrinkage of cement in cased-hole wells is important when dealing with the risk of sustained casing pressure (SCP). Current studies based on membrane tests suggest that, even with a high-percentage content of expanding agents, cement systems show little or no expansion in dry media. An alternative laboratory method for measuring cement expansion, followed by a successful field application, was used to evaluate the total bulk volume change of the cement based on curing in a dry environment and in water. Optimal cement-slurry properties were obtained. The developed cement system, which was successfully implemented in the field, provided long-term zonal isolation with no indication of SCP to date.
For a major operator in the Caspian region, drilling development wells required passing through shallow overpressured permeable zones containing water and biogenic gas.