|
| |
QC Tools and Techniques.
Start Up and Technical Audits
 |
Inspection of documentation for testing
carried out previously that is offered as substitute for tests for current
survey. i.e. recent gyro calibration.
|
|
|
Inspection of compass calibration reports.
|
|
|
Gyro calibration – if required.
|
|
|
rGPS verification – if required.
|
|
|
dGPS verification – if required.
|
|
|
Laser calibration – if present.
|
|
|
Inspection of monthly instrument tests.
|
|
|
Check of recording instrument time
settings. |
|
|
Check of gun line integrity (x-connection
and leakage). |
|
|
Gun/Airline air pressure leakage test.
|
|
|
Bubble test for gun volumes and depths.
|
|
|
Hydrophone polarity test.
|
|
|
Hydrophone sensitivity test (based on
signal decay not individual sampling).
|
|
|
Recording of signatures for all individual
guns, clusters and individual gun and cluster dropouts. |
Line
QC Tools, Tests and Reports.
|
|
Inspection
and entry of basic information from observer and navigation logs into
survey database. |
|
|
Stripping,
graphing, logging and inspection of data from P2 file.
 |
Water depths.
|
|
|
Vessel dynamics.
|
|
|
dGPS quality statistics.
|
|
|
dGPS system comparisons.
|
|
|
Streamer feathering.
|
|
|
Compass data.
|
|
|
Streamer and bird depths.
|
|
|
Gun volumes.
|
|
|
Gun air pressures.
|
|
|
Gun depths
|
|
|
Gyro data comparison.
|
|
|
rGPS range and bearing data.
|
|
|
Selected critical acoustic ranges.
|
|
|
Graphing of preliminary geometry
statistics |
|
|
|
Stripping,
graphing, logging and inspection of data from P1 file
|
|
Creation of CDP file from P1 file
including azimuth and offset data and edit flag.
|
|
|
Creation of receiver dynamic dS (and dX &
dY if dS outside specified criteria) bitmap. |
|
|
Graphing and logging of geometry
statistics. |
|
|
Comparison with QC P1 file.
|
|
|
Binning to Quality Qube of coverage.
 |
Overall coverage.
|
|
|
Coverage attained on the current pass.
|
|
|
New coverage attained on the current
pass. |
|
|
|
|
Processing
to produce QC P1 file. (If
Parallel QC Processing deployed)
|
|
|
Inspection of single
trace data.
|
|
|
Inspection of noise
files.
|
|
|
Inspection of shot
records.
|
|
|
Inspection
of gun logs.
|
|
|
Conditioning and
inspection of gun hydrophone data.
|
|
|
Inspection of brute
stack.
|
|
|
Inspection of processed
stack.
|
|
|
Creation and inspection
of seis-nav merge plot.
|
|
|
Addition of selected
near trace data to NT timeslice in Quality Qube.
|
|
|
Addition of selected
trace data to common offset timeslice in Quality Qube.
|
|
|
Creation and inspection
of source balance plot.
|
|
|
Creation, graphing and
areal plotting of noise data. Shallow window, full spectrum.
|
|
Shallow window, low
frequency. |
|
|
Shallow window,
specified spectrum. |
|
|
Deep window, full
spectrum. |
|
|
Deep window, low
frequency. |
|
|
Deep window,
specified spectrum. |
|
|
Signal to noise
ratio. (event trailed signal polygon)
|
|
|
|
Addition of selected
noise attributes to Quality Qube.
|
|
|
Addition of velocity
data to Quality Qube. |
|
|
Addition of weather
statistics to Quality Qube.
|
Survey-wide QC Items
Geophysical Quality Services have produced a new database to provide survey-wide
logging and display of data and attributes.
Quality Qube is a binary code file capable of storing
data in multiple dimensions for extraction as ascii data or bitmap images.
It is used to track and identify data that has a
significance over the whole of the survey. It is also used for binning of
seismic data to calculate coverage. Further uses include the production of
pseudo-cubes for single trace and constant offset data. Genuine single trace and
constant offset cubes may be produced using dedicated Quality Qubes separate
from the QC item.
The following items are conducted on
a time variant basis rather than a per line basis.
|
|
Inspection of daily,
weekly and monthly tests. |
|
|
Inspection of
feathering patterns with a view to minimisation of infill. |
|
|
Inspection of NT
cube for navigation integrity. |
|
|
Inspection of NT
cube and CO cube for velocity integrity. |
|
|
Inspection of
Quality Qube for noise patterns. |
|
|
Inspection of
coverage plots to review acquisition strategies. |
|
|
Inspection of
Quality Qube with reference to grouping of weather affected lines and SN
ratio. |
|
|
Mapping of pre-plot
lines, acquisition and other relevant items. |
|
|
Cross-survey single
trace slices. |
|
|
Update of selected
Quality Qube items to web site. |
|
