Seismic reflection and refraction is the
principal seismic method by which the
petroleum industry explores hydrocarbon-
trapping structures in sedimentary basins.
Both the seismic techniques have specific
advantages and disadvantages when compared
to each other and when compared to other
For these reasons, different industries apply
these techniques to differing degrees.
The refraction of
elastic waves on
formations of rock
Refraction observations generally employ fewer
source and receiver locations and are thus
relatively cheap to acquire.
Little processing is done on refraction
observations with the exception of trace scaling
or filtering to help in the process of picking the
arrival times of the initial ground motion.
Because such a small portion of the recorded
ground motion is used, developing models and
interpretations is no more difficult than our
previous efforts with other geophysical surveys.
Refraction seismic observations require relatively
large source-receiver offsets (distances between
the source and where the ground motion is
recorded, the receiver).
Refraction seismic only works if the speed at
which motions propagate through the Earth
increases with depth.
Refraction seismic observations are generally
interpreted in terms of layers. These layers can
have dip and topography.
Refraction seismic observations only use the
arrival time of the initial ground motion at
different distances from the source (i.e., offsets).
A model for the subsurface is constructed by
attempting to reproduce the observed arrival
The reflection of elastic
waves at boundaries
between different rock
as a technique for
prospecting or research.
Reflection seismic observations are collected at
small source-receiver offsets.
Reflection seismic methods can work no matter
how the speed at which motions propagate
through the Earth varies with depth.
Reflection seismic observations can be more
readily interpreted in terms of complex geology.
Reflection seismic observations use the entire
reflected wavefield (i.e., the time-history of
ground motion at different distances between the
source and the receiver).
The subsurface is directly imaged from the
Because many source and receiver locations must
be used to produce meaningful images of the
Earth's subsurface, reflection seismic observations
can be expensive to acquire.
Reflection seismic processing can be very
computer intensive, requiring sophisticated
computer hardware and a relatively high-level of
expertise. Thus, the processing of reflection
seismic observations is relatively expensive.
Because of the overwhelming amount of data
collected, the possible complications imposed by
the propagation of ground motion through a
complex earth, and the complications imposed by
some of the necessary simplifications required by
the data processing schemes, interpretations of
the reflection seismic observations require more
sophistication and knowledge of the process.
Environmental and engineering concerns generally opt
for performing refraction surveys.
Reflection surveys are extensively used in oil industry.
In situations where both could be applied, seismic
reflection generally has better resolution, but is
considerably more expensive
In other cases (e.g. very deep/small targets) only
reflection can be expected to work.
Where boreholes or wells are accessible, neither
refraction, nor reflection may be recommended in
favor of seismic tomography
Reflection technique potentially generates,
interpretable observations over complex geologic