Abstract: The acoustic wave field excited by a pulsed point source in a fluid-felled borehole surrounded by horizontal multiple-layered media is solved by the send-analytical method. The general reflected matrix between layers is found with the mode solutions so that field of every horizontal region is expressed by the general reflected matrix.The formal solutions of n-layered formation are obtained.Numerival calculation is made on three-layered medial out of borehole. The correct display of head wave arrival is got.The effect of the thin layer on the head wave arrival and amplitude is discussed.The work in this paper make it is possible to investigate the ability to divided layer longitudinally in acoustic logging.

Key words: horizontal multiple-layer, acoustic equation, a semi-analytical method(a hybrid method), mode solutions