Page 169 - Acquisition and Processing of Marine Seismic Data

160 2. MARINE SEISMIC DATA ACQUISITION

mobilized equipment, hardware and a. Information on the line and survey: Line name/
software lists, streamer configuration plots sequence number, data recording parameters
(Figs. 2.43 and 2.44), source drawings (start/end time, average vessel speed,
(Figs. 2.32 and 2.33), gun drop-out number of shots, record length, average gun/
specifications, misfire and bad record streamer depth, shot and sampling interval,
descriptions (Table 2.16), presurvey offsets, number of channels per streamer),
calibration results of the navigation production statistics, observer log of the
equipment (Section 2.6.1.1), vessel offsets line, etc.
diagram (Fig. 2.17), and towing diagram b. Visual inspection: Checking of the shots from
(Fig. 2.42). all cables along the line to define the specific
g. QC applications: Fast-track processing noise types such as strum/tug noise, seismic
sequence description, online and offline QC interference, strong swell noise, etc.
implementations for navigation, seismic data (Chapter 3) as well as auto-fires and misfires.
and source. This is usually done during the real-time QC
h. HSE plan for the survey: Vessel and company and reported in the per-line documents to
regularizations for potential issues on health, indicate shots/traces that must be edited
safety and environmental situations, HSE during the processing. A detailed and
management plan, permissions for complete listing of the shots/channels for
the operations, procedures for training and editing is provided after a visual inspection
safety drills (fire alarms, man overboard, of the data.
blackout vessel, abandon ship, oil spill), c. Noise evaluation: Noise records and RMS noise
overall risk assessments for the displays (Fig. 2.86) for each streamer at the
survey, emergency response plans and beginning and end of the line.
procedures. d. Data spectrum: Display of raw/filtered first
i. Other topics: Key persons for the survey and and last shots with their corresponding
their contact information (vessel amplitude spectra (Fig. 2.88).
management, data processing supervisor e. Fast-track processing results: Near offset gather
onboard and on land, party manager, fleet and brute stack.
and HSE manager, etc.), data formats, data f. Navigation information/plots: Line direction
storage implementations, deliverables, etc. plot, fold coverage map after the line,
additional plots of shot interval (Fig. 2.90),
2.6.5.2 QC Reports Per-Line gyro data (Fig. 2.89B), vessel speed (Fig. 2.91),
An offline quality control report specific to water depth plot (Fig. 2.98A) against the
each sail line, termed the per-line QC, for each shot point.
completed survey line is produced after a care-
ful analysis of the seismic, navigation and source 2.6.5.3 Daily Reports
data. These reports contain information specific Daily progress reports are prepared by the
to one single seismic line, and they are approved party manager onboard and submitted to the cli-
by the onboard client at the end of each sequence ent until the next work day at 08:00. These
to decide if the line is acquired within the quality reports simply indicate what has been done dur-
tolerances of the survey. If not, the client may ing the last operation day of the survey, statisti-
decide to reshoot the complete or a specific cal details of overall production and operations,
part of the line. In close connection with the meetings and other HSE implications, and com-
online QC analysis, per-line QC reports typically ments for the next day. A daily report typically
consist of the following items: contains the following information: