Blended Data Renders Visual Value

Contributors: Satinder Chopra, Kurt Marfurt

To co-render seismic attributes means to blend two or more seismic attributes into a single, unified data display.

As a result of efforts to demonstrate the value of volumetric interpretation of seismic data, most modern software allows interpretation on time or horizon slices, together with geobody detection and multi-volume and multi-attribute co-rendering.

Advanced display technology and visualization systems accelerate the interpretation process, create expanded insights into prospects and provide new means of communicating these insights to co-workers, management, partners and investors.

Merged Volumes Using Color

A false-color technique used to co-render seismic attributes plots three discrete attribute ranges using red, green and blue (RGB) colors:

  • Features imaged with higher values may be displayed in blue.
  • Geology described by intermediate values are shown in green.
  • Lower values are in red.

From experiences of mixing paints, most people know how these three colors blend, which makes this RGB technique a powerful data-integration and communication tool.

(The procedure has limited value, of course, for people who suffer from color blindness.)

Volume Co-Rendering

In the simplest implementation of RGB co-rendering, each voxel in 3-D space is assigned an RGB triplet, or color.

When an interpreter displays a number of vertical and horizontal slices, or displays one or more 3-D seismic volumes, only data nearest the interpreter are seen. By extending this three-component color model to a four-component RGB-alpha color model, where alpha is opacity (or transparency), each voxel can be assigned a reflective or transmissive property of specific strength.

Volume rendering consists of controlling the color and opacity of each voxel and projecting these properties onto an image plane. Such volume rendering allows interpreters to see and interact with features inside the 3-D volumes in their true 3-D perspective.

By using opacity as a function of the value of a given attribute, an interpreter can highlight features of interest within a sub-volume of 3-D seismic data and facilitate the understanding of spatial relationships between features of interest.

♦In figure 1a we show a strat-cube sculpted from a most-positive principal curvature volume correlated with a vertical slice through a seismic amplitude volume. Note how lineaments of most-positive curvature correlate with anticline features seen on the vertical seismic slice.

The opacity settings in figure 1b create a skeletonized image of the larger flexures, which can be used to tie vertical slices through the seismic amplitude volume.

♦In figure 2a we show a chair view of a vertical slice through a seismic amplitude and a strat-cube extracted from the corresponding coherence volume.

Note that two channel features are clearly seen in the middle of the strat-cube. These channels exhibit differential compactions, and the edges of the channels are well defined by low reflector coherence (black).

Next we show the equivalent chair view, but with most-positive principal curvature (figure 2b) and most-negative principal curvature (figure 2c) co-rendered with coherence. Only very low values of coherence have been retained. High and intermediate coherence values have been made transparent.

Note that the edges of the channels are again well-defined on the coherence surface. The channels appear as trends in which most-positive curvatures have their maximum positive values.

Our tentative interpretation is that these are two sand-prone channels incised in a shale matrix that has undergone differential compaction.

Consistent with this interpretation, the most-negative curvature anomalies define the edges of the channels (figure 2c).

♦In figure 3a we show an inline vertical slice and a phantom horizon slice 8 ms below an interpreted zero crossing. In figure 3b we show an equivalent chair view where the phantom horizon slice is correlated with most-positive and most-negative curvature volumes.

Using transparency, we have retained only the higher positive values of most-positive curvature and the lowest negative values of most-negative curvatures.

This co-rendered display shows red lineaments associated with the upthrown sides of the faults and blue lineaments associated with downthrown sides. Such displays convey more information than do strat cube displays made from seismic attribute or curvature attribute volumes.


♦Seismic attributes need to be visualized in such a way that they add maximum value to a seismic interpretation.

♦Three-D visualization capability can be a powerful tool to integrate different types of data.

♦Well log curves, VSP data or microseismic data also can be brought together in 3-D views to provide visual corroboration of data information and to build higher levels of confidence in interpretations.

Comments (0)


Geophysical Corner

Geophysical Corner - Satinder Chopra
Satinder Chopra, chief geophysicist (reservoir), at Arcis Seismic Solutions, Calgary, Canada, began serving as the editor of the Geophysical Corner column in 2012.

Geophysical Corner - Rob Vestrum

Rob Vestrum is chief geophysicist at Thrust Belt Imaging, Calgary, Alberta, Canada.

Geophysical Corner - Kurt Marfurt
AAPG member Kurt J. Marfurt is with the University of Oklahoma, Norman, Okla.

Geophysical Corner - Ritesh Kumar Sharma

Ritesh Kumar Sharma is with Arcis Seismic Solutions, Calgary, Canada.

Geophysical Corner

The Geophysical Corner is a regular column in the EXPLORER that features geophysical case studies, techniques and application to the petroleum industry.


Image Gallery

See Also: Bulletin Article

We use three-dimensional seismic reflection data and new map-based structural restoration methods to define the displacement history and characteristics of a series of tear faults in the deep-water Niger Delta. Deformation in the deep-water Niger Delta is focused mostly within two fold-and-thrust belts that accommodate downdip shortening produced by updip extension on the continental shelf. This shortening is accommodated by a series of thrust sheets that are locally cut by strike-slip faults. Through seismic mapping and interpretation, we resolve these strike-slip faults to be tear faults that share a common detachment level with the thrust faults. Acting in conjunction, these structures have accommodated a north –south gradient in westward-directed shortening. We apply a map-based restoration technique implemented in Gocad to restore an upper stratigraphic horizon of the late Oligocene and use this analysis to calculate slip profiles along the strike-slip faults. The slip magnitudes and directions change abruptly along the lengths of the tear faults as they interact with numerous thrust sheets. The discontinuous nature of these slip profiles reflects the manner in which they have accommodated differential movement between the footwall and hanging-wall blocks of the thrust sheets. In cases for which the relationship between a strike-slip fault and multiple thrust faults is unclear, the recognition of this type of slip profile may distinguish thin-skinned tear faults from more conventional deep-seated, throughgoing strike-slip faults.
Desktop /Portals/0/PackFlashItemImages/WebReady/Geometry,-kinematics,-and-displacement-characteristics-of.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 7962 Bulletin Article

Criteria for recognizing stratigraphic sequences are well established on continental margins but more challenging to apply in basinal settings. We report an investigation of the Upper Devonian Woodford Shale, Permian Basin, west Texas based on a set of four long cores, identifying sea level cycles and stratigraphic sequences in an organic-rich shale.

The Woodford Shale is dominated by organic-rich mudstone, sharply overlain by a bioturbated organic-poor mudstone that is consistent with a second-order eustatic sea level fall. Interbedded with the organic-rich mudstone are carbonate beds, chert beds, and radiolarian laminae, all interpreted as sediment gravity-flow deposits. Bundles of interbedded mudstone and carbonate beds alternate with intervals of organic-rich mudstone and thin radiolaria-rich laminae, defining a 5–10 m (16–33 ft)-thick third-order cyclicity. The former are interpreted to represent highstand systems tracts, whereas the latter are interpreted as representing falling stage, lowstand, and transgressive systems tracts. Carbonate beds predominate in the lower Woodford section, associated with highstand shedding at a second-order scale; chert beds predominate in the upper Woodford section, responding to the second-order lowstand.

Additional variability is introduced by geographic position. Wells nearest the western margin of the basin have the greatest concentration of carbonate beds caused by proximity to a carbonate platform. A well near the southern margin has the greatest concentration of chert beds, resulting from shedding of biogenic silica from a southern source. A well in the basin center has little chert and carbonate; here, third-order sea level cycles were primarily reflected in the stratigraphic distribution of radiolarian-rich laminae.

Desktop /Portals/0/PackFlashItemImages/WebReady/a-sequence-stratigraphic-framework-for-the-Upper-Devonian-Woodford-Shale.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 3250 Bulletin Article

See Also: CD DVD

Desktop /Portals/0/images/_site/AAPG-newlogo-vertical-morepadding.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 4326 CD-DVD

See Also: Energy Policy Blog

Those of us in the petroleum industry have been tracking the rapid expansion of oil and gas production from shales and in the process we may not have noticed the rapid expansion of renewable energy, especially wind. Read the latest Energy Information Administration (EIA) statistics.

Desktop /Portals/0/PackFlashItemImages/WebReady/renewables-are-booming-too-2014-08aug-08.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 12909 Energy Policy Blog

See Also: Field Seminar

This one-day field trip will take a quantitative view of the accumulation of sediment in the Denver Basin since the middle Cretaceous. We will systematically review the facies, thickness, organic content, rates of accumulation and paleoenvironments of the rocks that comprise the last 100 million years of deposition in the region.
Desktop /Portals/0/PackFlashItemImages/WebReady/ace2015-ft-10-hero.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 14697 Field Seminar