text: what is a dual gamma ray tool?   a dual gamma ray has two gamma ray sensors in it. if for instance you are drilling a horizontal well and its very important to stay within a said lithology in the reservoir, the dual gamma would prove useful. it would detect the gamma on the highside of the hole and then again on the lowside of the hole (top and bottom of the hole), thus you get 2 gamma traces to help if your geosteering.