Summary

Experiments on oil well cement (OWC) slurries were performed using the newly developed laboratory-scale wellbore simulation chamber (WSC). The WSC can simulate hydrostatic pressure reduction in the cemented annulus and possible gas migration under representative conditions. Forensic analysis shows that pressurized fluids can result in porous cement and gas channeling during cement slurry gelation. The effects of different factors on slurry pore pressure were also studied, including formation permeability, initial overburden pressure (OBP) representing the depth of interest, wellbore temperature, water/cement (w/c) ratio, cement composition, and the use of a calcium chloride (CaCl2)-based accelerator. By analyzing the temperature history of hydrating cement using degree of hydration, the evolution of cement hydration was characterized for slurry designs cured at different hydration rates. This provides the opportunity to parameterize the slurry designs and other important factors associated with wellbore conditions.

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