Distinguishing
Static and Dynamic Faults: Application for
Connolly, David1, Bill Fraser2,
Fred Aminzadeh3 (1) dGB Earth Sciences, Sugar Land, TX (2) Gulf
Energy Exploration Corp,
Distinguishing dynamic (leaking) faults
from static (sealing) faults is critical for risking seal and charge. This is
especially true in deep gas prospects such as Tertiary Gulf of Mexico and
others places where DHI may be inconclusive. Many conventional methods aim at
exploring for deep gas focus on finding effective reservoirs. However, often
times, there is an ambiguity on whether those reservoirs are charged. For
effective charging of deep gas reservoirs, it is necessary to detect dynamic
faults which terminate vertically in the prospective interval.
Static faults are often narrow and well
imaged on similarity or coherence data. They generally are dipping on vertical
sections. Dynamic faults, in contrast, are characterized by vertically aligned
chaotic zones in the seismic sections, often related to high shear stress. In
map view they are characterized by a complex of splinter faults with circular
pockmarks, often occurring at fault intersections. These vertically aligned
chaotic zones, or gas chimneys, can be detected using a pattern recognition
approach based on multi-dimensional multi-attributes and neural network
modeling. The result is a data volume which represents the probability of
chimney. When this chimney data is displayed along a fault trace, the dynamic
and static portions of the fault can be shown.
An example data set from Offshore,
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California