1. n. [Formation Evaluation]
An upgoing and downgoing arrangement of transducers in a logging tool, largely to offset spurious changes in reading caused by variations in borehole size or sonde tilt. The technique is used for measurements that rely on the propagation of a wave, such as sonic, propagation resistivity, and electromagnetic propagation measurement. Propagation logs rely on measuring the difference in properties of a wave at two receivers. The borehole influences this difference if the tool is tilted or if there is a cave opposite one of the receivers. The effect can be compensated for by using two transmitters that radiate sequentially in opposite directions. In ideal conditions, the effect of a tilt or a cave is exactly opposite for the two transmitters, so that an average gives the correct result. Borehole compensation is different from borehole correction.