Using XML and SVG in advanced geological information systems:

a case of cross-border UK-NL stratigraphy explored

Jan Jellema

Netherlands Institute of Applied Geoscience TNO- National Geological Survey

Ir. Jan Jellema, Princetonlaan 6, Postbus 80015, 3508 TA Utrecht, The Netherlands, j.jellema@nitg.tno.nl

Abstract

The use of the modern standards as XML and SVG is highly advantageous for structured knowledge bases, for example a stratigraphical covering of the southern North Sea

Introduction

The last decade HTML has grown into the de facto standard for information exchange over the web. HTML is, however, not well suited for presentation of data subject to change or data requiring various forms of representation. The reason being that HTML misses intelligence on content.

Two years ago XML has revolutionised ways to exchange and visualise information in a much more content focussed fashion.

XML allows to capsulate content in tags, which are extensively defined allowing the receiver of data to represent and visualise data in its own format. XML is finding its way rapidly into exchange data standards such as for POSC (reference) and GML (reference).

In terms of visualisation and representation, XML has great advantages to define custom tailored and dynamically adaptive presentation. Such features are extremely useful in environments were presentation requirements are different for various end-users (e.g. multilingual) or for different tasks, or require a particular combination or correlation of data which reside in the company_s knowledge base. Many examples dealing with these aspects can be identified within the Earth Science workflow. In this paper an example of such a case is drawn from the use of XML to a stratigraphical nomenclature. TNO-NITG is often faced with such requirements, from its responsibility to a large and very heterogeneous data-user community in an Internet environment. This paper describes various key aspects of the advantages for using XML techniques highlighted through an example of Cross-Border Stratigraphy UK-NL.

History

The Geological Surveys of the United Kingdom and the Netherlands both produced a Stratigraphic Nomenclature for the North Sea around 1995. The oil companies appreciated these activities, but the complaint was heard, that it was not possible to have an integrated overview of the southern North Sea. As the national boundary is exactly in the middle of the North Sea shelf, many formations are defined only on one half of the North Sea and unknown to the other half. On distribution maps the national boundary is often a formation boundary.

Functional Design

To develop a better understanding of North Sea geology, NITG-TNO has advised a combined knowledge center on Internet. Starting from the hierarchical stratigraphic table, it is possible to visualize all descriptions of the subsequent formations on both sides of the boundary. Complex configurations of groups, formations and members are illustrated with special made correlation tables. Every description of a unit is lavishly provided with borehole intersections, location maps, distribution maps, correlation panels and literature references, all directly accessible through hyperlinks.

Technical Design

First it was necessary to develop a logical framework for storing texts and drawings. The root object is a stratigraphical unit, with fields for location, type section, additional sections, lithology, upper boundary, lower boundary, correlation, distribution, age, depositional setting and subdivision. This model is recorded in a DTD (Data Type Definition).

All textual and numerical data is now converted to XML-files according this model. (eXtended Markup Language) Based on this datamodel one has the freedom to make a number of presentations in XSL (XML Style Language). The first presentation is a title HTML-frame with the name of the formation and several navigation buttons. The second presentation is more extended, to include the lithological definition. The third presentation includes all details on type sections and the textfields mentioned. All these frames can be selected to choose the optimal configuration on both sides of the national boundary. Standard procedure is to put the UK-information on the left half of the screen and the Dutch information on the right half of the screen.

This procedure gives a large advantage regarding user-interface flexibility. It is quite simple to build in future presentations for simple or expert users. One may zoom in on a more detailed level. It is even possible to build cross-queries, for example to show all formations deposited in a lacustrine environment.

For graphical presentation the SVG standard is chosen. All well descriptions, logs, interpretations, correlation diagrams and maps are transferred into this format. Although this vector-format gives a small additional burden to the client_s machine, it has the advantage of scalability. Thus even by large zooming manoeuvres the logs are still clearly visible as lines. This is highly appreciated by the geophysicists as they often need to study in detail the boundaries between two stratigraphic units. Through the abundant use of hyperlinks in the SVG-drawings and texts it is quite easy to switch between the horizontal map, the vertical borehole section and the full textual description. A service which replaces a desk full of books and drawings.

Also SVG makes it possible to produce intelligent maps, where the stratigrapher can peel of the layers one by one. Information, which is normally available in the legend can now dynamically be presented at the tooltip of the mouse. A short description of the pointed stratigraphic unit can be dynamically presented in a textbox below the drawing. In short, the heavy overburden of parameters in the usual geological map can be alleviated by dynamically providing only the information the user need on that moment.

Future research

First of all this application will stimulate the stratigraphers to complete the distribution maps of the mentioned formations. Also it makes it light to produce cross-border well correlations. Other local in-depth studies of a company, or institute information can be linked as study material.

In 2002 all Dutch formations in the southern North Sea are covered. In 2003 this will completed with all British formations. This system offers also the opportunity to integrate easily with German, Danish and Norwegian stratigraphy.

Further study will be made on the use of SVG for the topographic background. It would be perfect if the background is only constructed once and the distribution polygons and well locations will be dynamically drawn on the top of it. Integration with the geologic reconstruction maps and surface exposure maps could help the specialists.

Also the connection to 3-D data is interesting, as this allows a dynamic cross-section on the screen. This is a section, which can be turned, or moved forwards and backwards and gives so a 3D-insight of the geologic body to the reader. Up to this moment this has not yet been demonstrated on Internet.

Conclusion

The case study on the Cross-border UK-NL stratigraphy illustrates well the typical strength of using XML based techniques for Internet based knowledge systems. The structured storage of stratigraphic information in XML and SVG stimulates exchange of knowledge and offers an unprecedented flexibility of presentation to the stratigrapher. The system is scalable and easy to update.

Acknowledgements

The presented knowledge system on the North Sea stratigraphy has primarily been developed for the Nederlandse Aardolie Maatschappij, the Netherlands, which significantly funded the project and provided very constructive ideas and feedback.

References

POSC http:// www.posc.org/ebiz/

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