HR: 10:35h
AN: S22A-02    [Abstracts]
TI: An application of time-reversed acoustics to the imaging of a salt-dome flank
AU: Willis, M E
EM: mewillis@MIT.EDU
AF: Earth Resources Laboratory, Massachusetts Institute of Technology 42 Carleton Street, Cambridge, MA 02142
AU: Lu, R
EM: lurr@mit.edu
AF: Earth Resources Laboratory, Massachusetts Institute of Technology 42 Carleton Street, Cambridge, MA 02142
AU: * Campman, X
EM: xander@erl.mit.edu
AF: Earth Resources Laboratory, Massachusetts Institute of Technology 42 Carleton Street, Cambridge, MA 02142
AU: Toksöz, N
EM: toksoz@mit.edu
AF: Earth Resources Laboratory, Massachusetts Institute of Technology 42 Carleton Street, Cambridge, MA 02142
AU: Zhang, Y
EM: yangz@mit.edu
AF: Earth Resources Laboratory, Massachusetts Institute of Technology 42 Carleton Street, Cambridge, MA 02142
AU: de Hoop, M V
EM: mdehoop@dix.mines.edu
AF: Center for Wave Phenomena, Colorado School of Mines 1500 Illinois Street, Golden, CO 80401
AB: We present results of applying the concept of time-reversed acoustics (TRA) to the imaging of a salt-dome flank in a v(z) medium. A simulated multi-level walk-away VSP survey with sources at the surface and receivers in the borehole can be sorted into an equivalent reverse VSP (RVSP) with effective downhole sources and surface receivers. We apply the TRA process to the RVSP traces and create a zero offset seismic section as if it had been collected from collocated downhole sources and receivers. This procedure effectively redatums the wavefield from the surface to the borehole, eliminating the need for any complicated processing. The redatummed traces are created by summing the autocorrelations of the traces in the RVSP common shot gather. Theory says that each shot gather should be from receivers which completely surround the source. From practical considerations, we only have available the RVSP common receivers on the earth's surface, so we obtain an approximate zero offset section. Even with this restriction, our example shows that the results are encouraging. The image of the salt dome flank is created from the redatummed traces using a standard post-stack depth migration algorithm. This image compares favorably with the salt dome flank model.
DE: 7200 SEISMOLOGY
DE: 7203 Body waves
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7290 Computational seismology
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: Fall Meeting 2005