A large variety of slip-sweep scenarios were tested in order to better
understand the system-vehicle messaging and communication protocol
efficiencies. For example long sweep times combined with short slip and
listen times result in a larger number of overlapping sweeps, pushing
the central recording unit’s processing capabilities as well as driving for
efficient fleet ready, start, and PSS signal handling logistics. Messaging
protocols have been developed and are now being improved to avoid
signal collisions on the radio system. We evaluated and implemented
improvements in the following subsystems: fleet networking and vibrator
navigation, GPS source positioning, Vibroseis signature recording, sweep
and shot QC, and dynamic fleet grouping due to irregular move-up times.
All of the tests planned - slip-sweep, DSSS, DSSSS, and ISS - were
performed in the short time period available, as Crew 8622B needed
to demobilize and move on to a regularly planned seismic project. The
data was recorded in SEG-D format, simultaneously uncorrelated and
correlated. Both SEGD and SEGY formats can be chosen as a customer
decision for media output. In addition, the ground force for every sweep
was recorded and logged via flash disk drives connected to the Vib Pro
decoders in each vibrator. We achieved acceptable recording rates of up
to 260 VPs/ hour with four fleets of two vibrators, and up to 570 VPs per
hour with nine fleets of one vibrator, all in slip-sweep mode. Dynamic
fleet grouping was successful, with vibrators in both two- and threecluster DSSS operations able to match up on the fly with other clusters
when the vibrators were ready to sweep.
Independent simultaneous sweeping with eight vibrators was tested, and
uncorrelated, continuously recorded data, along with GPS clock timing
for every sweep, were acquired. Vibrators were able to start sweeps
independently of the acquisition system.
IN — Volume II, Number I
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