The Use of Autonomous Underwater Vehicles in Seafloor Massive Sulphide Exploration

Stevenson, Ian


Commercial exploration of Seafloor Massive Sulphides (SMS) requires mapping ofthe seafloor at a variety of scales, from regional mapping (> 10,000 km2)to detailed prospect delineation (1- 10 km2). Vessel-based multi beam echosounder (MBES) surveys are commonly used at the regional scale of mapping.Follow-up detailed high-resolution mapping has been undertaken with eitherROV's or deep-towed geosurvey platforms. To date, these techniques have yieldeda high success rate in the discovery of SMS prospects for Nautilus on itsexploration tenements.

With the SMS exploration and production industry still in its early stages,there exists significant opportunities in the re-application of existingtechnologies into this new industry. One technology where there is significantmarket benefit and growth potential is Autonomous Underwater Vehicle (AUV)technology. With a large tenement holding (almost 600, 000 km2 of explorationtenements granted or under application), Nautilus considers AUV technology hasthe ability to deliver faster and improved assessment exploration technique todecrease the cost and delivery time of prospective seafloor sampling and drilltargets.

Although the SMS industry is still in its infancy, it has been possible toevaluate AUV technology for SMS application through joint collaboration withMarine Science Research (MSR) groups with AUV capability, and a keen researchinterest in hydrothermal vents. To date, MSR group AUV's have been utilised inscientific expeditions over Nautilus Minerals' tenements on threeoccasions.

Nautilus Minerals is developing its plans to realise improved explorationquality and productivity with AUV technology including different operating /commercial models to meets its short through to long term explorationrequirements. An important consideration is to modify AUV payload design toinclude sensors specific to SMS exploration. Nautilus is currentlyinvestigating numerous geophysical sensor payloads which are not common tocommercial AUV survey solutions, but are seen as key to further improving SMStarget discovery rate.

This paper will provide a recap on the application AUV technology for SMSexploration and draw from a recent AUV "proof-of-concept" cruise to illustratethe potential of this technology.