winsism refraction seismic of w_geosoft geo2 x sa how to use the software ?
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Compatibiliy
• Window 7,8 (PDF display problem)
• Window Xp (no known problem)
• Windows 95, 98 (no known problem)
• Windows 2000 & NT (Occasional compatibility problems)
• Windows Me (Few feedback…)
Few abbreviations to know
• TT= travel time
• FBP= First break point
• IT=Intercept times
• BR=Bedrock
• GRM= Generalized Reciprocal Method
• SU=Seismic Unix
To convert SEG2 to SU, just select all records of a spread
Select your records
Convert to Su format
All shots data of one spread will be recorded into one large SU file !!!, Shot order must be the same as field recording order, shot 1 = first offset, shot 2=end shot 1
First break picking is the next stepPrecise picking is fundamental!
Use the scroll bar to select record
Select the SU file
Pick the FBP(First break points)
You can enlarge trace size, clip amplitudes and more… With the mouse reduce time display
How tu use automatic picking
First, click on the smallest break time with the right button
The move the scroll to adjust all FBP automatically
If necessary adjust parameters
Picking can be corrected later
Travel time structure•To give valuable informations a seismic refraction spread MUST have at least 2 offsets, 2 end shots one center shot (see REDPATH booklet) !
•You can have up to 48 shots and 96 receivers per shot
•Distance ZERO is END SHOT 1
•Offset 1 will have a negative distance
•All receiver distances are measured from END SHOT 1
Now, we can build the travel time (1)
You must enter few data
•File name
•Geophone spacing and number
•Shot spacing and number
Build the travel time (2)
Double click on the top first cell of shot 1 and the select the corresponding FBP file.Repeat for all shotsTime delay can be added to all times
FBP files can be renamed when used or reversed
Build the travel time (3)
Repeat for all shot and correct if necessary shot location and elevation
Click on SAVE and DISPLAY
Travel time correction 1
Select and display the SU file
Click on the FPB to correctTravel time is updated automatically
If necessary adjust display parameters
You can move any FBP time, double click on a point, keep pressed and release the mouse at the new correct location. To delete a point, double click on it and release without moving.
Travel time correction 3
Bed rock velocity determination
To know the BR velocity use the true velocity between the two offset shots
If you have not a straight line, you can have more than one BR velocity
If you know the number of layers save the BR velocity
Travel time movingYou can move the offset shot down to the End shot
You can determine:1. Which part of
the End shot belongs to bedrock
2. The intercept time for the end shot (Save it)
Bedrock arrivals
First and second layer arrivals
Velocity determination (1): Linear regression
Select a shot first and last geophone
Compute using linear regression and save the velocity for the correct layer number
Velocity determination (2)
You can draw a line with the mouse (Down, move Up), velocity is computed and can be saved (Menu PROCESSINGVELOCITY DETERMINATION)
Depth computation Intercept Time method
When all layer velocities and IT have been determined, you can compute the layer thicknesses and BR depthSelect shotComputeSave if not automatic
Coloured profile display (1)
Select the PROFILE PARAMETER tabAnd enter your choices Profile elevation and thicknessDraw shot or/and geophones
Click here to prepare the profile
Coloured profile display (2)
This graph can be saved as WMF, JPG file or copy into the clipboard and PASTE into any program (WORD, PAINT, CORELDRAW)Click on right button to launch graph editor
ABC method (2)
Move the total time line down to the end of shots
You can now compute time from surface to bedrock below all geophones
Delay times give a good idea of bedrock geometry, like furrows
ABC method (3)
If you already compute depth below shots, you can know the bedrock depth below all receivers
GRM method (1)
This method is not suitable if you have less than 24 geophones
First have a look on the velocity fonction curve to select the receiver spacing
See the PALMER thesis PDF file in the W_GeoSoft CD-ROM for all theory
GRM method (3)
Last step, depth computation below all geophones and save the values in the GRM grid file
Quick interpretation
You can have easily a first idea of depth with the QUICK INTERPRETATION module. The
Just select the shot number, the number of layer and move the layer limit
You can save depth and velocities in the WinSism WS4 file
WinSism menu
Display a TT Read a WinSism file Save a WinSism file Convert field records
FB picking Redisplay TT File info Correct a TT Build TT
Quick interpretation Trace moving Velocity linear regression Velocity point to point Velocity line True velocity
Thickness computation Printing Display profile ABC method GRM Method Zoom
Help Ruler EXIT
Most of the operations can be launched using pictograms or shortcuts