World's Largest AUV Survey Successfully Completed

Fugro was contracted by BP Exploration (Egypt) Ltd. to undertake a regional site investigation at Raven, located in the West Nile Delta using Fugro's Hugin 3000 Echo Surveyor AUV. Fugro was able to draw together the special skills of the local OpCo, Fugro SAE; Italy's Fugro Oceansismica S.p.A. and the UK's Fugro Survey Ltd and Fugro Ltd. Fugro Survey Ltd provided the Autonomous Underwater Vehicle (AUV), its payload and support vessel to carry out much of the geophysical survey work.
A total area of just under 1000km2 was surveyed and it is believed that this is the largest AUV survey carried out anywhere so far. The purpose of the AUV survey was to obtain seabed and sub-seabed hydrographic and geophysical data to aid in the design of sub-sea facilities, route selection for flowlines, pipelines & umbilicals and to detect and delineate all geo-hazards that may have an impact on facilities installation or well drilling. The survey took place during the latter half of 2005 using the survey vessel M/V Geo Prospector.

An AUV was chosen as the platform from which to operate the geophysical systems because it provides several significant advantages:

• The smooth track, constant speed and optimum height above sea bed provide data of the highest quality that it is possible to obtain, particularly in deep water
• The tightly coupled Inertial Navigation System adds rigour to the positioning of hazards and features
• The tight turning circle - "Echo Surveyor" can turn almost in it's own length - enormously reduces the time to change between survey lines.
• Improved data quality and positioning accuracy enables a confident interpretation of seabed and sub-seabed conditions
• Confident interpretation permits assured engineering that reduces risk and reduces cost.
• Faster data acquisition combined with tried and tested onboard reporting routines with high-speed satellite data link deliver faster results to the asset team.
• Faster results delivery can reduce development time and bring forward oil field revenue

The survey area covers several prospects and potential production facility locations with water depths ranging from 16m to 1089m. The AUV surveyed to a minimum depth of 75m and the near shore survey was carried out by traditional survey techniques using the M/V Flying Enterprise.

AUV data was acquired using a Kongsberg Simrad EM2000 multibeam echo sounder (150° opening angle) and an EdgeTech sub-bottom chirp profiler & 120kHz Side Scan Sonar (operated at a slant range of 200m). In addition to the contracted AUV instrumentation, the Geo Prospector's EM300 multibeam and EA500 single beam echo sounders were run for AUV data verification.

The line spacing was 150m with orthogonal tie-lies at 1000m intervals. Additional tie lines were also run within the survey area. The total number of line-kilometres surveyed by the AUV was in the region of 6750 kilometres and, when combined with the Flying Enterprise data, this resulted in a combined total of approximately 7700 line-kilometres. The AUV flew at height of 30m to 35m above the seabed at a speed of 3.6 knots. It continually acquired data from all its onboard sensors. All the AUV sensors were monitored on the Geo Prospector via an acoustic modem in order to provide a real time QC solution.

Our client is extremely pleased with the data and has commented:

• I have just seen the seabed bathymetry for the southern half of the survey area as processed onboard personnel. The results are stunning.
• I wish to express my admiration for the team onboard the survey vessel
• They carried out the survey in a truly professional manner and the deepwater data is nothing short of spectacular. Very well done.

Having completed another very successful in Indonesia, the survey spread is en route for other projects in South America and West Africa.

This project is one of an increasing number where the differing skills sets of the Fugro group are harnessed to focus on one integrated objective.