Client: Major oil company
Topic: Positioning QC for 3D transition zone seismic

Situation

To provide independent navigation QC services for a 3D transition zone (TZ) survey offshore Trinidad

Challenges

• Shallow water depths
• Manoeuvring around structures
• Fishing vessels
• Cargo vessels, recreational ships and ferries travelling in and out of the local ports

Actions

• Full QC of the positioning data,
• Approval of all navigation procedures, equipment tests, survey network control reports, vessel offset diagrams, dGPS antennae positions relative to a known datum prior to commencement of operations
• Survey of the calibration points
• Comparison of pre-plot and seabed ‘pinged’ locations to report any comparisons out of tolerance
• Independently check of all start-up verification procedures, acoustic positioning reports, preliminary and final SPS data prior to the final acceptance as deliverables
• Daily reports submitted to the client detailing meetings attended and information requested and received between departments
• Quality control comments on technical issues, field visits and HSE observations, START cards submissions and photographs

Results

Successful acquisition of accurately positioned transition zone seismic data in a location where there were many obstructions and vessels to negotiate