The next format for seismic data exchange may not come from the Society of Exploration Geophysicists (SEG). An ongoing World Wide Web Consortium (W3C) project for the exchange of binary data using XML has adopted seismic data as one of its ‘use cases’.
The W3C workgroup, with members from ChevronTexaco and Oracle Corp., states that XML-based techniques have had ‘little penetration’ into upstream oil and gas. The very large datasets typical of well logs or seismic data make for excessively bulky data files if regular, text-based XML encoding is used. This is in part why, according to the workgroup, POSC’s Well-LogML has had little take-up and also for the fact that ‘nobody has even considered defining a schema for seismic data.’
E&P datasets therefore make ideal use cases for the W3C’s binary XML initiative. Seismic and well log header data can easily be represented in XML. But the large arrays of floating point numbers lack an XML standard. One option therefore is to leave the header data in text-based in XML, but to en-capsulate floating point data in an ‘opaque’ binary data stream.
One mechanism for packaging binary data inside an XML control/header file is the W3C XML-binary optimized packaging mechanism, XOP. An XOP file contains the packaged binary much as a MIME encoded binary file is attached to an email.
Project member Ravi Murthy of Oracle Corp. told Oil IT Journal, ‘The W3C Binary XML Characterization group has made significant progress. The energy industry use case shows the potential overhead of an XML 1.0 text format. The workgroup is evaluating alternative encodings of XML and is expected to come out with a recommendation soon.’
Binary XML needs to be platform independent and to offer conversion tools to and from native formats. While compactness and speed are of the essence, data compression is unlikely to be considered. Prior experience compression has led many to ‘place a greater value on the message structures than the transmission mechanics’.
The W3C panel notes the potential for such a web-services approach to complement Corba-based integration (OpenSpirit) as currently deployed in upstream oil and gas.
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