Patent ID: 7646674

Claim:
A system for measuring a property of borehole environs comprising a formation penetrated by a borehole, said system comprising: (a) a tool conveyable within said borehole; (b) an acoustic transmitter disposed within said tool, wherein (i) said transmitter transmits an asymmetric acoustic pulse into said borehole environs, and (ii) said acoustic pulse generates a plurality of acoustic modes within said borehole environs; and (c) an acoustic receiver array disposed within said tool and axially displaced from said transmitter; wherein (i) said receiver array comprises at least two receiver stations at different axial spacings from said transmitter, (ii) each said station responds, at a plurality of azimuthal positions, to said modes generated by said transmitter, (iii) said responses are combined using angular decomposition to simultaneously identify said modes, and (iv) said identified modes are used to determine said property.