Transcript No Slide Title

Geology 490M 3D Seismic Workshop
Looking at our prospect in depth
tom.h.wilson
[email protected]
Department of Geology and Geography
West Virginia University
Morgantown, WV
A combination of Geometrical
and Velocity anomalies
Recall this generalized structural model of the Summit field north of
Morgantown, WV from earlier in the semester. The blue colored
anticlines are cored by salt, which also served as a detachment
interval or decollement zone. The deeper strata dip gently to the east.
How will the distribution of fast and slow rocks affect the appearance
of the seismic time section?
Remember what a buried focus event is?
The buried focus
Velocity “Pull-Up”
What doesn’t look right in this seismic section? Why does it appear?
Travel time is reduced to the lower reflector beneath
the anticline.
Reef
Scattered ray-paths produce the geometrical distortions
What would you expect to happen here?
Note the subtle velocity anomaly beneath the channel reflections.
In most exploration endeavors you will have some well log information,
and formation depth information scattered through the area.
With horizon depths
from wells and
travel times form the
seismic data
it is easy to compute
velocity.
Velocities derived over our survey area.
Where are the most likely structural traps located?
Recall possible
interpretation based
on the set of “2D”
lines ...
5 millisecond
contour
interval
Where are the most likely structural traps located?
In 2-way traveltime we had weak prospects with
limited and questionable closure
Before we forget …
Let’s decide when to get together
for our oral presentations
The 8:30 to 9:30 MWF classes have exams scheduled for
11:00 am to 1:00 pm on Wednesday, May 8th.
All in favor ...