A particular combination of a spontaneous potential log and three electrical logs consisting of a 16-in. (40-cm) short normal, a 64-in. (162-cm) long normal and an 18-ft, 8-in. (5. 7-m) lateral. With this combination, it is possible to correct for the effects of invasion in many average logging environments. This combination is sometimes called a conventional electrical log or survey, or simply electrical log, and is also referred to as the ES.