Pioneer Pipe Route Surveying
An important milestone was the first commercial survey operation with HUGIN I for the Aasgaard Gas Transport Pipeline Route in 1997. This survey confirmed that the expected improvements in efficiency and data quality were realistic. The main characteristics of the survey are detailed seabed topography survey and a 200km route corridor. The results from these operations showed that:
• in general, the vehicle showed an excellent offshore operational performance and reliability;
• in shallow waters it collected data at a significantly (four times) greater efficiency than what was achieved by the remotely controlled vehicle (ROV); and
• the handling system prototype proved to be an adequately efficient and safe method for launch and recovery of the vehicle throughout the weather conditions of this operation (even when operated in Sea State 5).
Figure 2
Pipeline Pre-engineering Surveying
Another important milestone was passed in October 1998 with an exceptionally challenging pre- engineering survey carried out in a deep fjord on the West Coast of Norway. The survey covered a seabed area of extremely rapidly varying topography with water depth in the range of 300–550m, including narrow passages. This survey operation fully confirmed the capability of the vehicle to operate in this type of terrain with respect to navigation, positioning, communication and vehicle operation, as well as the performance of the survey sensors.
Environmental Monitoring and Fishery Research
In June 1998, the first environmental test survey was carried out by the Institute of Marine Research (IMR), Norway, using HUGIN II to map an area scattered with coral reefs. In a single six-hour mission, an area of 7,000 (600m (4.2km2)) was mapped. In January 1999, IMR tested HUGIN II as a sensor carrier for fishery research instrumentation. The EM3000 MBE was replaced with a 38kHz Simrad fishery sonar. Apart from realistic testing of the system configuration, the objective of the operation was to determine the noise level of the vehicle. Excellent-quality echograms were recorded, and noise measurements verified that it has avery low noise level for the application. Since then, more fishery research projects have been carried out with the most recent one in November 2002 surveying the extreme concentration of herrings in the Ofotfjorden, North Norway.
Figure 3 The Ormen Lange field survey
Offshore Surveying – NorthSea
One example from offshore surveying with AUVs is the survey operations carried out at the Ormen Lange gas field in the Norwegian Sea in 2000, 2001 and 2002. Ormen Lange is a significant gas province located in an area with water depths exceeding 800m. Parts of the area contain very rough terrain with significant slide areas. In order to provide sufficient and detailed survey data for the subsea installation design phases, Norsk Hydro decided to use AUV survey technology. Significant detailed site and pipeline route surveys have been carried out by the Norwegian survey companies Geoconsult and Stolt Comex using the NUI Explorer AUV. The results have shown high efficiency, high accuracy and high level of details. The detailed information unveiled by the survey will contribute significantly to the further work of planning and selecting the most optimal site and route for the production and pipeline installations, according to Norsk Hydro.
Offshore Surveying
During the last four years, C&C Technologies Inc. has successfully operated the HUGIN 3000 on a regular basis in the GoM. Surveying has been carried out in water depths down to 2,400m proving its capabilities in the rough escarpments leading down to BP’s GoM deepwater fields. C&C Technologies Inc. has also operated the vehicle off west coast of Africa, off Brazil and in the Mediterranean. A total of more than 18,000 survey line kilometres has been successfully covered in water depths down to 2,850m. The intended increase in cost-efficiency, data resolution and precision has been repeatedly demonstrated. The actual time and cost consumption by use of these vehicles have been proven to be in the range of 1/3’’ to 1/2’’ of the traditional deep tow systems.
The Future
With more knowledge of the seabed, the potential is greater for cost savings in design of subsea constructions. The technology to survey and map the seabed is available with this AUV design. Time and cost-efficiency to gather these highly detailed data is proven, so can oil companies afford not to use it?
Category:
Transportation
| 
Download PDF
