"Critical-application cementing" can mean many things: high-temperature/high pressure, cyclic gas storage wells, extended-reach and horizontal, deep water, hazardous waste disposal wells, or simply trying to get a decent job across a weak zone.  Regardless of the classification, the goal is always zonal isolation whether faced with sustained casing pressure, protection of potable aquifers, or maintaining cement sheath integrity under the extreme stresses encountered in a HTHP gas well.  Even the most benign of wellbore conditions can be challenging under the right circumstances.  This presentation will touch on some of those issues that are challenging even to the cementing experts, along with issues that are often either overlooked, oversimplified, or not considered significant.