3DPSTM: 3-D Kirchhoff Prestack Time Migration 3DGeo's 3-D Kirchhoff prestack time
migration (3DPSTM) package is based on a state-of-the-art implementation of the algorithm
designed to achieve maximum efficiency on parallel-vector and cache-based supercomputers.
The algorithm includes several choices of anti-aliasing and an amplitude equalization operator
to preserve the amplitude information in the final image even when the spatial sampl ing of the
input data is irregular. Through scaling of the input and output data 3DPSDM can be run on
workstations as well as supercomputers, though the best efficiency is obtained on larger
computing platforms. The 3DPSTM implementation handles both straight and curved rays.

Geophysical Aspects
Kirchhoff migration is recognized as
the most flexible method of imaging
prestack 3-D seismic data. 3-D
prestack migration of surface seismic
data is the ultimate tool for imaging
the Earth's subsurface in areas of
complicated geological structure and
velocity. Kirchhoff migration is
particularly appropriate for 3-D
prestack data, because of its flexibility
in imaging irregularly sampled data
and because of its relative computational efficiency.

3DPSTM: an advanced migration algorithm At the core of the 3DPSTM package is the data
summation engine, designed to execute efficiently on parallel-vector and cache-based
supercomputers. The 3DPSTM inner kernel uses very long vectors to take advantage of vector
architectures while the output image is divided into processing blocks that are distributed over
parallel processors. The problem of load balancing the computation across processors is solved
by exploiting the locality of the Kirchhoff migration operator; that is, a seismic data record
collected in a certain area of the survey will mostly contribute to the part of the seismic image
that is directly below the recording location. Locality is exploited by designing an optimal
partitioning scheme for both the input and the output data.

The user can choose from several anti-aliasing methods that enhance the imaging and
resolution of steep faults and salt-sediment interfaces.
Scalable software implementation 3-D prestack data processing requires very powerful
computers for efficiently handling the large number of computations necessary to accurately
image the data. While more efficient on large platforms, 3DGeo's 3DPSTM software can be run
on a variety of computer sizes and architectures. Through scaling of the input and output data,
the design of the 3DPSTM ensures that the same problem can be solved on workstations or
supercomputers.

Easy Integration The 3DPSTM package is modular in design and can be customized and
integrated into a client's specific environment. 3DPSTM is available on Unix workstations,
parallel-vector and cache-based supercomputers, and other architectures. If desired, 3DGeo
can integrate the package into a client's processing environment or add it as a Promax, Focus
or Views module.