By Felicity Goldrick, Principal Consultant Data Management
Seismic surveys are a major investment and a key asset. Failure to archive all the different component items of survey acquisition and processing data to a single, safe, and known archive can carry a heavy cost in the long run. To borrow a well-known phrase, “location, location, location” would be a fitting mantra for seismic data management: location of raw data; location of processed data; and location of (and you’ve guessed it!) location data (aka navigation data).
Location – acquisition data
The three main components of modern seismic acquisition are typically delivered piecemeal, by varied means and not always to the same recipient. This separation is the root cause of many problems locating acquisition data. Here is a short list of key data to keep your eyes on:
- Seismic Field Tapes
It is now standard practice to record two sets of seismic field tapes, dispatching one to the Processing Contractor and the other to the Operator. Output will usually be in SEG-D format on multiple 3592 cartridges.
- Raw Navigation Data
Typically output in P2/94 format on 3592 cartridge. Sometimes only one set is output at source and this is dispatched to the Processing Contractor, but can often become detached from the main database.
- Support Data
There is no single defined list of support data; it should always include Observer Logs and Tape Listings. These may still be recorded on paper, but hopefully will be in digital text or Excel format. Delivery will be to the Processing Contractor.
At the end of acquisition, the Acquisition Contractor must write up a report. The report will be sent to the Processing Contractor and should be emailed to the Operator for their record. Ideally it will contain a checklist of all the acquisition data showing who has received what, when, and how.
Location – navigation data
The P1/90 format navigation files comprise the essential processed navigation data set used for loading SEG-Y to the Workstation for interpretation. They are output in the initial processing and are often an early deliverable emailed to the Operator. It is important these are logged and stored safely.
- Location – processed data final deliverables
The Processing Contractor will send data to the Operator at multiple stages of seismic data processing over a period of several months. Mainly SEG-Y format, these files might each cover only part of the survey area. Managing the flow of early versions and duplicates must be an ongoing procedure, requiring careful management and cataloguing. It is important the final agreed deliverables are responsibly archived and clearly differentiated from working files. Here are some typical outputs:
- Fast track SEG-Y
Provided via sFTP
- Final SEG-Y
Provided via sFTP or on USB HDD
- Key SEG-Y volumes
Output on archival media (3592 cartridge)
- Velocity files
Provided via sFTP
At the end of processing, the Contractor must write up a report for the Operator. Delivery is typically by email. Ideally it will contain a checklist of all delivered data showing who has received what, when, and how. Processing reports should be kept with the original dataset to ensure easy retrieval for future reprocessing and operator transfer.
In Summary:
Efficient retrieval of seismic data sets requires good archival procedures. Archiving should be planned, then actioned simultaneously as the Acquisition and Processing Contracts are each signed off. This will reduce lost time and stress hunting for data and lay the foundations for successful project delivery.
If you would like friendly, expert advice for your archive planning or assistance tracking down seismic data, please contact the Merlin Datawise team:-
requests@merlin-datawise.co.uk or call Dr Sandy Smith on +44 01684 540091.
