If AUV survey design does not consider the practical limits to change detection and include best practices to minimize noise, however, the results may be ambiguous or even useless. Using a series of simulations combining real bathymetric digital elevation models (DEMs) with idealized perturbations representing seafloor subsidence and faulting, this paper examines limits to seafloor change detection using repeat MBES surveys in terms of the standard deviation of the noise in the surveys. In general, the magnitude of vertical change between surveys should be greater than the standard deviation of the noise (also known as uncertainty or error) in each of the surveys compared in order reliably recognize seafloor change. Filtering can suppress noise and recover the real seafloor change, possibly even if the magnitude of the change is less than the standard deviation of the noise. Based upon the simulations in this paper, filtering is more effective for broad features like subsidence bowls than localized features like faults even if the amount of vertical change is identical.
Seafloor massive sulfides (SMS) which contain Au, Ag, Cu, Zn, and Pb have been interested in as a target of commercial mining these 15 years. Japan has large potential of SMS and a national R&D project for the mining has been active these 5 years. However, the economy of SMS mining is very bad, because the waste tailing disposal cost is very expensive in Japan. A slurry flushing method is experimentally examined in this study for the improvement of the economy. During the flushing, because of density difference between the metal-rich ore and the waste rock, a kind of gravity separation is possible. The results suggest a possibility of the actual application.
The evaluation of fault sealing is an important step in the calculation of fault trap reserve. When it comes to the issue of complex 3-D fault trap structures and thin reservoirs, how to appraise and calculate the reserve properly and effectively is still a subject that needs further researching. In this respect, a certain rift basin that has experienced multi-periods rift movement and evolved in a fluvial faces and braided deltaic depositional environment has been chosen as the object of our research on fault trap evaluation and calculation of reserves. The method has been preformed in the following steps. 1) The tectonic evolution and the structural characteristics of the studying area are accomplished through 3-D seismic interpretation; 2) Based on the results of the well to seismic combination, the provenance direction sedimentary system interpretation and sedimentary evolution are completed; 3) On the basis of achievements of the tectonic evolution and sedimentary evolution interpretation, the 3-D fault trap geologic model is established by spatial interpolation. A certain method invented by Li Qingzhong is employed to forecast the fault trap reserves quantitatively. Moreover, this method can be described as follows. Constrained by the seismic horizons, fault data and sedimentary isochronous interfaces, the connected sand body units in every depth slice of the 3-D fault trap geologic model can be identified automatically. Meanwhile, their sealing degree and connectivity is appraised quantitively from the top slice to the bottom slice. Finally, through quantitative calculation of reserves for fault trap, the effective forecasting of reserves has been achieved. The results of our work have testified that this appraisal method can be applied to improve the prospecting accuracy and reserve forecasting precision of fault trap reservoirs.
Copyright 2012, SPE/APPEA International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production This paper was prepared for presentation at the SPE/APPEA International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production held in Perth, Australia, 11-13 September 2012. This paper was selected for presentation by an SPE/APPEA program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers or the Australian Petroleum Production & Exploration Association Limited and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers or the Australian Petroleum Production & Exploration Association Limited, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers or the Australian Petroleum Production & Exploration Association Limited is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.
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.
Roth, Ben (VCCER) | Hernon, Katie (Department of Mines, Minerals, and Energy) | Lassetter, William (Department of Mines, Minerals, and Energy) | Ripepi, Nino (Virginia Center for Coal and Energy Research)
Park, Se-Hun (Korea Ocean Research & Development Institute) | Yang, Hee-Cheol (Korea Ocean Research & Development Institute) | Lee, Kyeong-Yong (Korea Ocean Research & Development Institute) | Moon, Jai-Woon (Korea Ocean Research & Development Institute)
Yamazaki, Tetsuo (Osaka Prefecture University Sakai, Japan) | Ikemoto, Masahito (Osaka Prefecture University Sakai, Japan) | Nakatani, Naoki (Osaka Prefecture University Sakai, Japan) | Arai, Rei (Osaka Prefecture University Sakai, Japan)
The distribution characteristics of chemosynthetic communities around seafloor massive sulfide deposits provide important quantitative background information for the understanding of these sensitive ecosystems. Using visual seafloor observation data obtained by a towed camera system, a preliminary quantification approach of the distribution of chemosynthetic communities around seafloor massive sulfide deposits is presented. A manual visual definition and a semi-automatic color intensity analysis of the seafloor video images are the methods tested for quantifying the distribution. Some requirements for improving the approach are discussed.
Kuroko-type seafloor massive sulfides (SMS) in the western Pacific have received much attention as resources for gold, silver, copper, zinc, and lead for the commercial mining by private companies (http://www.nautilusminerals.com; http://www.neptuneminerals.com). Since the end of the 1980s, SMS have been found in the back-arc basin and on oceanic island-arc areas at 1 to 2 km of water depths. The typical representatives found are in the Okinawa Trough and on the Izu- Ogasawara Arc near Japan (Halbach et al, 1989; Iizasa et al. 1999), in the Lau Basin and the North Fiji Basin near Fiji (Fouquet et al., 1991; Bendel et al, 1993), and in the East Manus Basin near Papua New Guinea (Kia and Lasark, 1999). The high gold, silver, and copper contents in one of the areas have increased the likelihood that mining would be profitable, and a pioneer commercial mining venture is scheduled to start in a few years (http://www.nautilusminerals.com). However, no quantitative data is available for the environmental assessment of the mining, though many scientific observations have been conducted by ROVs and manned submersibles. A preliminary quantification approach of the distribution characteristics of chemosynthetic communities around the SMS deposits are introduced in this study.