Wellbore heat loop systems, fillers for bores in the systems, and methods of the use of such systems; the systems in certain aspects having a heat loop wellbore in the earth having heat loop pipe extending down to one side of a bottom member and up therefrom on another side thereof, the bottom member in certain aspects having a body with first and second bores therethrough, the second bore sized and configured for securement thereat of an end of coil tubing; and, in certain aspects, filler material around the heat loop in the wellbore with a gel material mixed with the water.