Author: Mike Cline, T/X Resources
Imagine a wall of water, with a flow rate of over one million cubic meters (35.31 million cubic feet) per second, rushing towards you—an amount that is 100 times the average flow rate of the Mississippi River today!
If you were crossing the broad chalk ridge (indicated by the thin, red line in the gray-shaded image below) that connected Britain with mainland Europe sometime between 200,000 and 450,000 years ago, you could have witnessed this ridge-busting torrent that ultimately separated the two countries.
See the larger Adobe Reader pdf file (two pages).
You can also watch a video report from the BBC News.
Author: Mike Cline, T/X Resources
While we’re on the subject of channels…………….
Here is a “quick-look” visualization technique, accomplished within SMT’s VuPak program, which can be used for prospect scanning of new 3D seismic volumes—either standard migrations, or other seismic attributes such as angle/range-limited AVO (amplitude-versus-offset) volumes.
This prospect scanning technique highlights interesting seismic amplitude details in much less time than when standard, vertical seismic displays are used for the interpretation, and it also lessens the chance that subtle anomalies will be overlooked. The example shown here, is another presentation of the channel in the previous two postings, and is accomplished by quickly discriminating larger amplitude events from the “background noise.
See the VuPak animation (29MB Media Player avi file).
Note: The avi file is fairly large, so it will take some time before the animation starts.
Author: Mike Cline, T/X Resources
After I finished the earlier posting, “Shaded Relief Maps for Subtle Fault Detection“, it occured to me that there may also be an interest in map displays for stratigraphic interpretation. This posting, and the one that immediately follows, illustrates how various map types and parameters can affect a stratigraphic interpretation presentation.
In the first slide in the series below, an autopicked two-way time color-filled map, a channel-like feature can be seen in the upper left quadrant of the mapping area. As we will see in later illustrations, it is fortunate that this colorbar was used—the channel may not have been as evident with other colorbars, as it is in this display. However, other than the two bounding faults (areas with the black crosses, indicating the manually-interpreted faults), not a lot of other structural and/or stratigraphic detail is evident. You can tell that the channel is draped across a nose, located between the red, high area to the northwest, and a gray area southeast.
See the larger Adobe Reader pdf file.
Author: Mike Cline, T/X Resources
Now for the less effective channel map displays:
Initially, I had included this portion in the original posting, “Effective (and Less Effective) Channel Maps” (see above). However, after thinking about it a while, I decided that it was too long, so I broke it up into two postings.
See the larger Adobe Reader pdf file.
As I mentioned in part one, the Channel TWT Color-Filled Map in the first slide of this series of images, is not as definitive because of the poor choice of colorbars. The upthrown fault block colored in red, increases the time range of the colors so much that the middle fault block, where the channel is located, is almost entirely in the green colors. This is the cause for the loss of color contrast, leading to less definitive channel edges. A map’s “dynamic range” (the spread of the largest-to-smallest values) is a key consideration when deciding on a colorbar.
Author: Mike Cline, T/X Resources
How fortuitous! I received my version 8.2 update of SMT’s Kingdom software this afternoon, and just got it installed. One of the new features that has been added to this version of 2d/3dPAK, is the ability to display the Shaded Relief of a grid. So, I thought that this would be a good time to introduce the technique to those viewers not familiar with the general concept. However, since I haven’t had a chance to get completely familiar with this newest feature in the SMT software, the surface and map displays shown below were created in my normal work flow using Golden Software’s Surfer program. As time permits, I’ll try to review, and compare, SMT’s new feature.
What is a Shaded Relief display? It is a map view of an artificially illuminated 3D surface whereby shadows are cast by minor deflections in the surface (shadowed deflections are facing away from the illumination source). This type of map is an excellent way to highlight smaller faults which may not have been seen, or noticed, on the vertical seismic displays.
See the larger Adobe Reader pdf file.
Author: Mike Cline, T/X Resources
Usually, color-filled maps are utilized for structure map presentations. Preference, or habit? If this applies to you, why not consider using a 3D shaded surface display, which transfers so much more information than a standard color-filled map, to display an interpreted horizon or gridded surface?
The animated display below compares an “overhead view” of a color-filled map, with a perspective view of a 3D shaded surface display. The black crosses on the color-filled map indicate where seismic faults were manually interpreted (at 500′ increments—or, every fifth inline and crossline in the 3D seismic survey).
See the larger Adobe Reader pdf file (two pages).
Author: Mike Cline, T/X Resources
In this SMT VuPak 3D perspective display, only the largest 30% of the seismic troughs (negative amplitudes) have been selected. In conjunction with this amplitude extraction, the “Base of Channel” horizon, fault interpretation, along with the nearby wellbores have been selected for viewing. This results in an impressive cloud of large amplitudes, which exhibits a distinct, and channel-like sinuous character (red event, highlighted by yellow arrow), in close proximity with other controlling geologic features.
See the VuPak animation (18MB Media Player avi file), or see a larger Adobe Reader pdf file.
Note: The avi file is fairly large, so it will take some time before the animation starts.