"How often do cables stick? It seems to me to be some inherent condition that happens to be down there stuffing things up wherever they decide to drill."
Cables sticking is relatively common. Id say that roughly 40% of the wireline jobs Ive worked had varying degrees of differential sticking of the cable going on. In many cases it wasnt severe enough to warrant abandoning the logging job but in all cases I would have had The Rig Supervisor in the wireline unit every 5 minutes asking me when I was going to finish the run.
The condition that is the root cause of differential sticking is quite simple....1) a permeable formation and 2) a mud weight high enough to lead to allow movement of the liquid phase of the drilling fluid from the borehole into the formation. You cant control permeability so the only thing you can do is control mud properties. You can do a few other things to minimize the risk of sticking...eg wireline tool design and tool configurations (eg standoffs, flywheels etc) and minimizing time tools are stationery in the hole.
