Page 142 - Acquisition and Processing of Marine Seismic Data

2.6 QC IN DATA ACQUISITION 133

TABLE 2.7 Level-1 Quality Control Assessments for
Marine Seismic Surveys Approved by Duty
Preparing near trace gathers and brute stacks
Approved by Duty
Hydrophone polarity and sensitivity tests
Chief Tests of guns, compressors, gun controller
mechanic Collecting the noise records
Verification of source array layout
Collecting the test record, if required
Performing the bubble tests
Checking the near-field signatures of all air
guns
Checking the gun pressures (Table 2.8). The party manager and onboard QC
manager perform the third level of QC assess-
Verification of source depth
ments by verifying all the QC procedures and
Checking the air leakage reports, and checking of overall data quality
Chief Tests of navigation system and related (Table 2.9). All available QC reports, related data
navigator devices and other QC-related products are then submit-
ted to the onboard client for a final approval.
Verification of navigation parameters
DGPS verification and gyro calibration
Preparing streamer layout TABLE 2.8 Level-2 Quality Control Assessments for
Marine Seismic Surveys
Verification of shooting parameters
Real-time checking the positions of in-sea Approved by Duty
equipment
Chief field Checking and approval of level-1
Controlling the vessel speed geophysicist quality control assessments
Checking the feather angles of all streamers Project start-up report
Checking the bird/acoustics/steering Project daily reports
devices status
Checking and improvement of onboard
Preparing the preplots processing flow
Preparing real-time binning and fold map
Chief Tests of recording unit, tape drives, data
observer transmission TABLE 2.9 Level-3 Quality Control Assessments for
Marine Seismic Surveys
Verification of recording parameters
Real-time checking the seismic shot data Approved by Duty
Checking the RMS noise level Party manager Checking and approval of level-2
quality control assessments
Analyzing the specific noise types and
overall data quality Project final report
Checking the missed shots Checking of overall data quality
Checking the static shifts between recorder Onboard QC Checking and approval of level-2
and gun controller manager quality control assessments
Checking the amplitude spectra of the Coordination with onboard client about
selected shots QC issues
Continued Checking of overall data quality