Workstation issues - 3-D Seismic Interpretation - page 193

Appendix 1

Workstation issues

This appendix covers briefly the main issues involved in managing hardware, software and data to
create an environment for the interpretation of 3-D seismic data. No attempt will be made to discuss
specific details of individual vendors' offerings, as they change very quickly; rather, the objective is to
give a general overview of the requirements for the creation of a successful interpretation environment.

A1.1 Hardware

The volume of seismic data in a 3-D survey is often large. As we saw in chapter 3 , a modest survey
may contain 500 000 traces each of 1000 samples. A large survey might contain tens of millions of
traces. It is quite usual to have several versions of the data volume (e.g. near and far trace stacks for
AVO analysis, perhaps several different inversion results, and calculated attribute volumes such as
coherence). Storage requirements for the trace data may amount to several to a few tens of gigabyte
(1Gbyte = 10 9 byte). If a company has interests in a number of licences, each with its own 3-D
survey, the total volume of seismic data may amount to a few terabyte (1 Tbyte = 10 12 byte). Storing
such a volume on disk is possible, but the cost will be less if some of the data are held offline on
magnetic tape, preferably in a high-density format (e.g. helical scan) that will allow large volumes
(e.g. 100 Gbyte) to be stored on a single tape. Rapidly changing commercial priorities will dictate
that the archive of data on tape is not static, but will need to be retrieved and reworked, maybe with
only a day or two's notice. Robust data administration procedures are needed to make this possible.
A further complication arises in a large integrated project, where several users may need access to
the same seismic dataset. Instead of each interpreter having his or her own workstation which runs
interpretation software on data held in local disk storage, issues of cost and version control may then
dictate that all data are held centrally and accessed by software that may also be run on the central
server or may be run on the interpreter's workstation. Computer power and data access time on the
central server and bandwidth of the network between it and the interpreter's seat will then dictate
system performance, and need careful consideration to get good performance in a large installation.
As with all computer systems, backup of work in progress is critical. The interpreter's work
needs to be backed up onto tape, preferably at the end of every working day. Many installations
have found that proper backup is more certain to be carried out if it is managed centrally rather
than by the individual interpreter. This is another driver towards centrally held and managed data
stores. Where there are many interpreters involved, the amount of data to be backed up each day
will become large enough to need detailed planning; high-density tape drives are a suitable medium,
but an efficient system is needed to make sure that all the required backup is completed in the time
available.

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