Advanced Acoustic Propagation Models Enhance Seismic Survey Planning

Stress wave propagation through range and depth variant inhomogeneous media now economically possible

Formerly the exclusive domain of a few defence specialists in long range geoacoustic surveillance and sonar systems design, realistic geoacoustic wave propagation
modelling is now available to commercial users for seismic survey parameter selection, geologic modelling, and earthquake prediction.
 

Choose optimum sources, receivers, data acquisition, and processing for your seismic data in advance of your survey

If some of the geoacoustic characteristics of an area are known in advance of a seismic imaging survey, say from boreholes or other geologic indicators, then a
representative model of the area can be constructed and the performance of various seismic surveying instruments, acquisition geometries, and processing for
imaging the target objectives can be evaluated.

The Marschall Acoustics Group of Australia is a leading commercial developer of wave propagation models.  Marschall Acoustics computer codes can model acoustic
and vibrational wave propagation through media whose properties are variable in both range and depth.  All elastic waves can be solved for: P-waves, S-waves,
and wave conversions including interface waves.   The calculation of synthetic seismic traces is straightforward after computing the complex transmission loss
functions for a range of frequencies.

These synthetic seismic traces can then be used to evaluate the necessary specifications for imaging survey equipment and acquisition geometries, evaluate signal
processing algorithms, and research geologic models of the area.  Results from forward modelling may also be used iteratively to derive inverse wave equation
model ("migration") parameters.

Many of these same acoustic wave equation numerical methods can be employed with some modifications to forward model electromagnetic waves as well.  These
electromagnetic wave propagation models are used to predict Active EM system survey performance and plan Active EM subsurface imaging surveys.  They also
find use in communications system design, antenna design, and radar system evaluation.
 
 
The above is a cross section of computed transmission loss amplitude as a function of depth and range for a 50 Hz acoustic source in 230 m deep water above 770 m of geology.  White and red contours represent the greatest intensities, blue and black the least.  Note the vertical scale represents 1 km in depth while the horizontal distance scale is 10 km.  Black line indicates sea bottom interface.  This particular example used a parabolic equation approximation (PE) solver which is most cost effective for problems with radial symmetry. Marschall Acoustics Instruments Pty. Ltd. is also licensed to use the full three dimensional Iterative Dual Domain Method (IDDM) which is of order n log(n) by Marschall Acoustics Pty. Ltd.