Dictionary:Long-spaced sonic log
A sonic log (q.v.) run with a tool having a spacing (see Figure S-13) between source to receiver array of 8–12 ft versus 3–5 ft for the normal sonic tool. Designed to measure formation properties beyond the portions possibly altered by invasion. Permits a more robust analysis of both P- and S-waves. Requires mode conversion to generate S-waves and therefore works best in fast formations.