Spilled oil from stranded ship damages not only the ocean environment but also the regional economics. In order to prevent such damages from expanding, we are developing a system using autonomous buoys. When the oil spill accident happens, several buoys are dropped into the sea. While the buoys drift along with spilled oil, those send some useful data such as its location, the meteorological and oceanographic data around them, in real time. According to the effect of wind driven water currents on the free surface, the buoys tend to drift apart from spilled oil. Therefore, the buoys must have the function of detecting and tracking spilled oil. In this paper, the concept of the buoy system and the mechanism of tracking spilled oil are firstly introduced. Then, the sensors to detect spilled oil are described. Next, the numerical scheme is explained to design the buoy and verify its maneuverability. Some experiments using a buoy model were carried out to verify the maneuverability and tracking ability of this buoy. These results show that the buoy could track the target by using the developed tracking algorism. 0-933957-35-1 ©2007 MTS As shown in Fig.4, DC servomotor rotates semi-submerged drum with constant frequency. To fulfill heave-free condition of this drum, some floaters are attached inside of it. It enables this sensor system to keep the draft of the drum 40 [mm] and 0-933957-35-1 ©2007 MTS J

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This paper describes the ongoing project on autonomous spilled oil and gas tracking buoy system and application to marine disaster prevention system for 5 years since FY2011. Objectives of this project are as (1)autonomous tracking and monitoring of spilled plumes of oil and gas from subsea production facilities by an underwater buoy robot, (2)autonomous tracking of spilled oil on the sea surface and transmission of useful data to a land station through satellites in real time by multiple floating buoy robots, (3)improvement of the accuracy of simulations for predicting diffusion and drifting of spilled oil and gas by incorporating the real-time data from these robots. To realize (1) and (2) objectives, we have developed an autonomous underwater robot named SO-TAB-I, and an autonomous surface vehicle named SOTAB-II. To realize (3) objective, Data fusion methods in the simulation models incorporating real time measured data not only from a SOTAB-I for gas and oil blowouts, but also from multiple SOTAB-IIs for spilled oil drifting on sea surface were developed.

It is important to forecast the location of oil spills to realize effective and adequate oil spill response operations when huge oil spilsl occur. In order to enhance the accuracy of oil drifting simulations, one needs to obtain the meteorological and oceanographic data around the oil slick. In general, the drifting velocity vector of an oil spill contains a wind velocity vector and a water current velocity vector. SOTAB-II was developed for autonomous tracking of oil slicks drifting on the sea surface. It is equipped with a sail whose size and direction are controllable to drift along with the oil slick autonomously. In addition, SOTAB-II transmits its location and necessary measured data around it to the land base in real-time. The results of field experiments using SOTAB-II with a cylindrical hull brought us the effectiveness of the sail and its control. However, the drifting speed of SOTAB-II was lower than a theoretical speed for the oil slick. In order to overcome this problem, SOTAB-II was redesigned. A yacht shape was adopted to reduce the hydrodynamic drag in the water in the advancing direction. Transverse stability, scales of brake board and sail, maneuverability, and performance of tracking spilled oil on the sea surface were considered in the process of the design.

Oil spills caused by accidents from oil tankers and blowouts of oil and gas from offshore platforms cause tremendous damage to the environment as well as to marine and human life. To prevent oil and gas accidentally released from deep water from spreading and causing further damage over time to the environment, early detection and monitoring systems can be deployed to the area where underwater releases of oil and gas first occurred. Monitoring systems can provide a rapid inspection of the area by detecting chemical substances and collecting oceanography data necessary for enhancing the accuracy of simulation of behavior of oil and gas. An autonomous underwater vehicle (AUV) called the Spilled Oil and Gas Tracking Autonomous Buoy system (SOTAB-I) is being developed to perform onsite measurements of oceanographic data as well as dissolved chemical substances using underwater mass spectrometry. The scope of this paper is limited to the surveying abilities of SOTAB-I in shallow water, although it also has functions for surveying in deep water. The experiment results obtained during the early deployments of SOTAB-I in the shallow water of the Gulf of Mexico in the United States are provided. Oceanographic data, such as the water column distribution of temperature, salinity, and density, as well as the dissolution of chemical substances were measured. In addition, a high-resolution water current profile was obtainable near the seabed. <def-list> Nomenclature <def-item> <term>ADCP</term> <def> acoustic Doppler current profiler </def> </def-item> <def-item> <term>AUV</term> <def> autonomous underwater vehicle </def> </def-item> <def-item> <term>BTX</term> <def> benzene-toluene-xylenes </def> </def-item> <def-item> <term>CTD</term> <def> conductivity-temperature-depth </def> </def-item> <def-item> <term>DVL</term> <def> Doppler velocity logger </def> </def-item> <def-item> <term>GPS</term> <def> global positioning system </def> </def-item> <def-item> <term>MIMS</term> <def> membrane introduction mass spectrometry </def> </def-item> <def-item> <term>PID</term> <def> proportional-integral-derivative </def> </def-item> <def-item> <term>PSU</term> <def> practical salinity units </def> </def-item> <def-item> <term>RMSE</term> <def> root mean square error </def> </def-item> <def-item> <term>UMS</term> <def> underwater mass spectrometer </def> </def-item> <def-item> <term>USBL</term> <def> ultra-short base line </def> </def-item> <def-item> <term>VOC</term> <def> volatile organic compound </def> </def-item> <def-item> <term>VRU</term> <def> vertical reference unit </def> </def-item> </def-list>

Development and operation of underwater robot for autonomous tracking and monitoring of subsea plumes after oil spill and gas leak from seabed, and analyses of measured data Author(s) Choyekh, Mahdi

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