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IXRefraX™
Seismic Refraction
processing and interpretation using GRM
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Designed for Windows 9x, NT® and
XP®
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Protected with convenient USB key
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Supports most seismic formats
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Automatic first break picking
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Manual first break picking by keyboard or mouse with amplified display
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Automatic assignment of arrivals to layers with manual override
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Access to arrival assignments and first break picks from GRM
interpretation window
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Presentation graphics with velocity color fill and arc plots for
consistency checks
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Documentation consists of a detailed Windows Help and a PowerPoint
tutorial
IXRefraX is the successor to
GREMIX and FIRSTPIX, our DOS based seismic refraction data processing and
interpretation system. It combines the features of both packages in one
integrated system and adds bold and powerful new ideas and features!
New
is the simple 2-D forward and inverse modeling. This is designed mostly to
automate the GRM interpretation by providing a means of assigning arrivals
to layers and determining X-Y values and reciprocal times (where data
cannot estimate them). However, the forward and inverse modeling can be
used to interpret data sets which lack the redundancy required for GRM
interpretation.
Data Import – RAW Shot Record Trace Data
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Shot data formats for SEG-1,
SEG-2 and SEG-Y formats are auto-detected.
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There is virtually no limit on
number of shots that can be imported to a profile.
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Data can be appended so
historical data can be combined with modern data.
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ASCII file import of tabulated
travel time curves is also available.
IXRefraX™ screen showing a shot
record with amplified window near first break pick.
First Break Picking
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Reads first breaks from files on
import or auto-picks as the files are imported.
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Arrow and page keys are used to
move cursor or use mouse to position cursor.
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Amplified trace section
displayed in window on top of trace display.
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Click mouse or press space bar
to pick break.
IXRefrax™ Shot header editor can
save, open move or generate geometry of spread.
Shot
and geophone spread geometry is read from shot record files as available.
Geometry can be created simply and easily and then saved for further use.
Addition and multiplication functions allow for shifting and manipulating
of existing spread geometries.
Travel time curves can be
automatically interpreted using slope-intercept methods.
It
is useful to have some information about the earth structure to construct
a starting model for the 2-D inversion. Automatic slope-intercept
interpretation allows for quick estimates in cases where the earth is
relatively flat. Knowledge of ground truth is also useful to have.
Starting with a model which is
flat or mimics the topography, inversion methods develop a result that
fits the data closely enough to assign arrivals automatically.
Once a general idea of the velocities and depths is conceived, this is
used to generate a starting model which is perfected by inversion to get a
reasonable fit to the data. The resulting model is then used to assign
arrivals to layers and estimate reciprocal times for shot pairs which do
not have valid estimates from the data values themselves.
Model screen showing ray paths
from sources to receivers
The simple 2-D model can generate
ray paths to illustrate the sampling of the subsurface by the rays which
give rise to the travel time data. The forward and inverse modeling can be
used to interpret data which lack the redundancy required for GRM
interpretation.
The GRM interpretation is
automatically generated and the individual segments are presented to the
user for perusal, editing, masking and evaluation
Each shot position is used to
build as large a shot record as possible using all data recorded from that
shot position. These are combined in forward-reverse pairs to generate
segments which are then interpreted using GRM and presented for evaluation
by the user. Segments can be masked (rejected for use in the combined
section), the reciprocal time can be edited, arrivals can be reassigned
and even the first breaks for the shots used in generating the segments
can be repicked.
Once the GRM interpretation for
all shot pairs is compiled, inconsistencies among interpretations for
different segments can be investigated, even back to the first break picks
on the original shot records.
Once the data has been examined
and edited by the user, the GRM interpretation can be regenerated.
Interpreted depth section showing
color fill of velocity and arcs for consistency.
Eventually, the segments are combined into a single cross section. Colors
can be used to denote velocities and arcs can be drawn to illustrate the
consistency (or lack thereof) in the interpretation.
Data and Depth section view
showing error bars on depth estimates.
Error bars are calculated when interpreted GRM segments are averaged
and presented
on the graphical display
in the depth
and elevation sections.
Elevation section showing color
coded velocities.
The user
has control over the color coding
of the velocities
so that each section is colored
in the same
way for comparison.
XYZ file output showing map and
profile coordinates with velocities, depths, elevations and time-depths.
ASCII file output
of interpreted GRM results can be generated
in an XYZ format for importation into third-party software.
User has control over output
of map
and/or station coordinate output,
as well as control over output
of velocity, depth, elevation
and/or time-depth values.
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