A FEW SEISMIC SURVEY EXAMPLES OF BEFORE AND AFTER
AUDITING
IMAGINE A PROCESSOR TRYING TO GET THE
DATA TO LOOK GOOD, USING A SEG FILE
SUCH AS THIS, SHOWN HERE IN GREEN
AFTER LOOKING AT THE SURVEY NOTES,
IT WAS DIFFICULT TO SEE HOW THE LINE WAS LAID OUT.
ONLY AFTER SEEING A SKETCH OF THE LAYOUT IN THE OBSERVER REPORTS,
COULD THE SURVEY NOTES BE UNDERSTOOD AND AUDITED
WE CAN SEE HERE HOW THE RECEIVER STATIONS WERE LAID OUT
FROM THESE RECEIVER LINES,
OFFSET SHOT POINTS WERE PUSHED OFFLINE.
SURVEYED AT RIGHT ANGLES FROM SOME STATIONS
OVERLAYING BEFORE AND AFTER FILES SHOW
HOW IT COULD BE DIFFICULT TO INTERPRET THE DATA
WITHOUT A QUALITY SURVEY AUDIT
LINE LOCATION BEFORE AUDIT IN NORTHERN BC
AFTER SURVEY WAS AUDITED,
THE SEISMIC LINE NOW FOLLOWS THE CUTLINE
100 METERS
STATION 152
STATION 150
NOT ONLY WAS THE LINE OUT NORTH TO SOUTH,
BUT ALSO EAST TO WEST,
AS SEEN HERE WHERE THE DIFFERENCE IS 2 STATIONS
ANOTHER BC LINE, THIS ONE WAS MOVED SOUTH.
OLD SEISMIC LINES ARE STILL EASILY SEEN IN THIS AERIAL PHOTO
HERE IS ANOTHER LINE IN BC, CANADA.
AFTER OVERLAYING TO IMAGERY,
IT WAS CLEARLY TOO FAR SOUTH OF A CUTLINE
AT FIRST CHECK TO
IMAGERY,
IT LOOKED LKE THIS
LINE WAS OKAY.
PROGRESSING FARTHER
SOUTH,
THE CUTLINE ENDED,
BUT THE SEISMIC
CONTINUED ON.
AFTER SEEING THAT
THE ELEVATIONS
DID NOT MATCH THE
DEM, FURTHER
INVESTIGATION WAS
NEEDED.
THE GREY GRID LINES
ARE TOWNSHIPS
6 MILES APART
BEFORE AND AFTER
LOCATIONS
FOLLOWING SLIDES
SHOW SOME QUALITY CONTROL CHECKS
THAT CAN BE USED
WHEN AUDITING IS NOT POSSIBLE,
DUE TO LACK OF FIELD SURVEY DATA.
THEY HELP TO VERIFY THE LOCATIONS.
THIS LINE WAS MISSING ALL
BASIC DATA.
NO OBSERVER REPORTS,
CHAINAGE OR SURVEY NOTES.
NOTHING FOR ANY CULTURE
CHECKS.
USING A LIST OF NOHOLES
AND
OVERLAYING TO IMAGERY.
YOU CAN SEE SP 1284 MISSING
WHERE A
ROAD CROSSES.
THIS SAME LINE
WAS IN EUROPE.
HERE WE SEE
MORE MISSING
POINTS ACROSS A
GREEN AREA &
CANAL
VERTICAL PROFILES FOR THIS LINE
TOP PROFILE IS FROM THE GIVEN SEG FILE
BOTTOM IS FROM DIGITAL ELEVATION MODEL
FOR THIS LINE THERE IS A VERY CLOSE MATCH
• FOLLOWING LINE IS FROM SOUTH AMERICA.
• THE FIELD SURVEY AND OBSERVER NOTES WERE AVAILABLE FOR SOME LINES.
• UNFORTUNATELY THE SURVEY DID NOT HAVE SURVEY CONTROL THAT COULD BE
CONFIRMED.
• FOR THESE LINES WE WERE ABLE TO FIND SOME CULTURE CHECKS USING
IMAGERY AND DIGITAL ELEVATION MODELS.
• AREAS LIKE THIS ARE HARDER TO PROVE LOCATIONS, DUE TO RAPID JUNGLE
CANOPY GROWTH, HIDING CULTURE CHECKS BELOW.
• HERE RIVERS CAN CHANGE LOCATIONS DRAMATICALLY OVER THE COURSE OF
YEARS.
HERE IS A COMPARISON OF FIELD ELEVATIONS TO GOOGLE EARTH
TOP GRAPH IS GOOGLE, WHICH IS WEAK IN THIS AREA
ELEVATIONS ARE CLOSE THOUGH AND FOLLOW THE SAME TREND
THE PREVIOUS GRAPH SHOWED DEM AND THE SURVEY, THEY SHOW A GENERAL
TREND THAT THE OVERALL ELEVATIONS MATCH, HELPING TO CONFIRM THE LINE
LOCATION.
FOLLOWING SLIDES SHOW SOME CULTURE CHECKS TO IMAGERY, THESE WERE
FOUND AS COMMENTS IN EITHER THE OBSERVER REPORTS OR SURVEY COMPUTER
LISTINGS.
THIS LINE WAS MISSING ALL THE ORIGINAL FIELD SURVEY DATA.
WE DID HAVE SOME SKETCHES AND COMPUTER LISTINGS.
AS PER SURVEY COMMENTS,
THE LINE STARTS AT THE RIVER
A CREEK CAN BE SEEN AT 383.5
STATION 383.5
THIS WAS NOTED AS CANO
IN THE COMPUTER SURVEY
LISTINGS
HERE A HOUSE IS HOUSE NO HOLE 502.5
SHOWN AT SHOT
POINT 502.5
THIS WAS NOTED IN
THE OBSERVER
REPORTS AND WAS
NOT SHOT
“SKIP X CASA” PAGE
22 OF OBSERVER
REPORTS
HERE ANOTHER SP 535.5
WATER CROSSING.
NOHOLE 535.5
(SKIP X CANO,
PAGE 24 OF
OBSERVER
REPORTS
RIVER NOTED IN SP 584.5
SURVEY NOTES AT
SP 584.5
RIO AFILADOR
PAGE 21 SURVEY
COMPUTER
LISTINGS
WRONG DISTANCE
WAS USED. 184M
INSTEAD OF 24M
FIELD
MISCALCULATION AT
STN 359.
THIS WAS NOT
CORRECTED
AND IS IN THE
COMPUTER LISTINGS
AND THE SEG FILE.
THIS STN WAS OUT BY
24 METERS IN
ELEVATION.
THESE ERRORS ARE
USUALLY NOTICED
WHEN PROFILING.
THIS IS AN EXAMPLE OF WHAT WAS CAUGHT WITH ONE OF OUR QC’S
TO PROPERLY ASSESS THIS TYPE OF SURVEY, ORIGINAL FIELD SURVEY WOULD
ALLOW FOR A FULL AND PROPER SURVEY AUDIT WHEN POSSIBLE.
OTHERWISE, THROUGH CLOSE EXAMINATION OF THE FIELD DATA, COMPARISON
TO IMAGERY AND DIGITAL ELEVATION MODELS, WE CAN HELP TO MINIMIZE
LOCATIONAL ERRORS.