3-D seismic data visualisation - 3-D Seismic Interpretation - page 172

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3-D seismic data visualisation

Recently there has been a change in the way that interpreters view seismic data. The
traditional method of working, as explained in chapter 3 , has been to make different
2-D sections through the 3-D data volume, as inlines, crosslines, random tracks or time
slices. The only way to view more than one section at a time was to open multiple
windows and view each one in a separate display. Today, largely thanks to relatively
low-cost computer power and memory, it is possible to view entire datasets so that the
interpreter can quickly get a feel for the actual 3-D nature of the trap. Indeed, several
different data volumes can be viewed simultaneously to interrogate various attribute
volumes at the same time (fig. 7.1) . This has many applications. As shown in fig. 7.1 ,
reflectivity and coherence volumes can be viewed simultaneously when interpreting a
fault; this is a way to combine the lateral continuity information from coherency with
the identification of the nature of a feature in the standard reflectivity section. Such
technology can also be used to view different AVO volumes in the same display, or to
examine reflectivity and acoustic impedance (inversion output) volumes at the same
time. Different time-lapse seismic volumes (see chapter 8 ) can be displayed so that
production-related changes can be more easily seen.
Also, various types of data can be viewed together with the seismic traces. In fig. 7.2
we see the top reservoir map viewed together with well trajectories and overlain with
satellite imagery data of the surface geology. Figure 7.3 is a more traditional combina-
tion: the top reservoir horizon together with the 3-D seismic volume from which it was
picked. The ability rapidly to scan through the entire seismic data volume together with
the reservoir pick is a very quick way of understanding where the picks may require
adjusting. For this type of work, display speed is critical. To check the consistency of a
pick across a volume of seismic data, the interpreter needs to keep in his head a picture
of how the pick looked on the previous view while examining a new one. If it takes
several seconds to redraw the display to show a new line, it is hard to maintain this
mental picture; the ideal is to have the display change to follow cursor movement on
the screen fast enough that the delay caused by the redrawing is not perceptible.
One of the advantages of having the entire data volume loaded in memory is that it is
quick to sculpt out different portions of the seismic data. There are many ways to do this.
A simple technique is to use interpreted horizons to guide sculpting; for example, data

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