Mixed Source Acquisition
, Elk Hills and Buena Vista Hills, California
B. R. Currin
Bakersfield, CA
During the past 18 months Occidental of Elk Hills has operated two
3D
seismic
surveys
across Elk Hills and one 2D survey across Buena
Vista Hills. Phase 1 and 2
3D
surveys
across Elk Hills covered 150
square miles, and entailed the
acquisition
of 38262 vibrator and
10549 dynamite source points. The Buena Vista 2D seismic project
consisted of 12 lines, totaling 141 line miles and entailed the
acquisition
of 5751 vibrator and 957 dynamite source points. Vibrator
energy source
surveys
must be augmented with dynamite due to
complex land use issues such as “conservation areas,” rugged terrain
and agriculture. Dynamite testing is relevant, even though it was
used as a secondary source in these
surveys
, because dynamite usage
tends to be clustered while in either
3D
or 2D mode. Dynamite
testing show that depth of shot is a key parameter decision, while
charge size is of lesser importance. Which energy source is “better?”
Dogma within many southern San Joaquin Operators has traditionally
been that vibroseis is superior in terms of penetration and bandwidth.
Results from the recently acquired Buena Vista 2D program,
however, offer strong arguments in contradiction to this traditional
view. Source signature matching between vibroseis and dynamite can
be facilitated by examining vibroseis versus dynamite in both CMP
stack and CMP gathers. Examples demonstrate significant data degradation
when this issue is unresolved.
AAPG Search and Discovery Article #90904©2001 AAPG Pacific Section Meeting, Universal City, California