COMPUTER METHOD TO DETECT AND CORRECT CYCLE SKIPPING ON SONIC LOGS.

A simple but effective computer method has been developed to detect cycle skipping on sonic logs and to replace cycle skips with estimates of correct traveltimes. The method can be used to correct observed traveltime pairs from the transmitter to both receivers. The basis of the method is the linearity of a plot of theoretical traveltime from the transmitter to the first receiver versus theoretical traveltime from the trasmitter to the second receiver. Theoretical traveltime pairs are calculated assuming that the sonic logging tool is centered in the borehole, that the borehole diameter is constant, that the borehole fluid velocity is constant, and that the formation is homogeneous.