32 equipment & cabling update
Sensor upgrades for
deepwater survey AUVs
Tony George presents a comparison of
and stronger electronic housings capable of withstanding
data collected with the first and second
increased water depth pressures. Sensor upgrades in the
latest generation of AUVs have resulted in improved high-
generation autonomous underwater resolution geophysical data.
vehicles.
C & C Technologies Inc (C&C) entered the
deepwater AUV survey market in January 2001 with the
C
ommercial, deepwater survey AUVs used commissioning of a Simrad HUGIN 3000 AUV, C-Surveyor
primarily in the oil and gas industry are I. A team of company engineers and technicians integrated
approaching nearly a decade of use. The a geophysical system payload of side scan sonar,
speed and efficiency at which these systems subbottom profiler and multibeam echosounder. Processing
operate in deepwater have saved exploration and routines were developed for merging the positioning and
production companies millions of dollars in development geophysical data. C-Surveyor I is equipped with three
survey costs when compared to conventional survey primary geophysical sensors: Edgetech Dual-Frequency
techniques. Project timelines from the discovery well Side Scan Sonar, Edgetech DW-216 Chirp Subbottom
to first oil production have decreased significantly due Profiler and Simrad EM3000 Multibeam Echosounder. The
to AUV technology. Larger AUV platform designs allow 3000 metre depth rated system operated primarily in the
space for more powerful sensors, longer life batteries Gulf of Mexico during the first two years of service. The
system was plagued with significant downtime, but the
mission success rate was improved with time as lessons
were learned and improvements to subsystems were made.
C-Surveyor I has been working on long-term contracts in
Brazil for the past several years.
Deepwater survey market demand in 2005 resulted
in C&C investing in a second Simrad AUV, C-Surveyor
II. This AUV is a Simrad HUGIN 3000 with the same
geophysical payload as C-Surveyor I. The subbottom
profilers in these systems worked well in the Gulf of
Mexico (Fig. 1), but very poor records were logged with
the system in the deepwater of West Africa (Fig. 2).
Fig. 2. Comparison of C&C AUV subbottom profiler data
from 2005 (DW-216) and 2008 (DW-106) collected
along nearly the same transect in West Africa.
Data courtesy of BP.
In 2007 the deepwater survey market looked promising
and C&C invested in C-Surveyor III, a Simrad HUGIN
4500 AUV with an increased water depth rating of 4,500
Fig. 1. Comparison of DW-106 (top view) subbottom profiler data and meters. This AUV is larger than its predecessors. The side
DW-216 (bottom view) subbottom profiler data collected across a sonar system in this AUV is an Edgetech DF (Dynamically
mound feature in the east-central Gulf of Mexico. Focused) 3200 Side Scan Sonar (230 kHz). The sonar
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