Imaging
the
Earth
using Incoherently Scattered Seismic
Waves in Exploration Geophysics
D. M. Leslie
Curtin University of Technology, Dept. of
Exploration Geophysics, Perth, Western Australia
Seismic methods are commonly used by the petroleum industry to
obtain reflections from geological boundaries that are prospective for
oil and gas production. In the presence of strongly scattering rugose
or high-velocity layers at or near the Earth
’s surface, no coherent
signal is received from the subsurface. This research will use and
extend the technique of Time Reversed Acoustics (TRA) in an effort
to solve this
imaging
problem.
Numerical and physical modeling
will be conducted using the developed
imaging
techniques. Preliminary physical
modeling
using
simple models in a homogeneous background was conducted at the
Laboratory of Waves and Acoustics (Paris) in 2000. The complexity
of this study will be extended to simple geophysical models deliberately
obscured by multi-scattering layers placed between the model
and the signal source. Mathematical methods for achieving suitable
imaging
of the model will be developed and tested.
The first outcome of this research is a better understanding of the
diffuse and multiple scattering processes in seismic exploration,
which obscure the coherent signals used currently in seismic processing
and imaging
of the
Earth
’s interior. The ability to construct
images below multiply scattering layers would open up areas for oil
and gas exploration which are currently precluded due to the lack of
coherent signal reflected from the subsurface.
The improved understanding of multiple scattering of seismic signals has the potential for the development of new data processing techniques to image the subsurface in areas where no seismic signals can otherwise be obtained. Examples particular to Australia include the North West Shelf, Timor Sea, and offshore Perth Basin.
AAPG Search and Discovery Article #90902©2001 AAPG Foundation Grants-in-Aid