3. 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

Oil spills produced 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 that are accidentally released from deep water from spreading and causing further damage to the environment over time, early detection and monitoring systems can be deployed to the area where underwater releases of the oil and gas first occurred. Monitoring systems can provide a rapid inspection of the area by detecting chemical substances and collecting oceanographic 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) has been developed to perform on-site measurements of oceanographic data as well as dissolved chemical substances using underwater mass spectrometry. In this chapter, the outlines of SOTAB-I and a description of its hardware and software are presented. The operating modes and guidance and control of the robot are detailed. The experimental results obtained during the early deployments of SOTAB-I in the shallow water of the Gulf of Mexico in the USA demonstrated the ability of SOTAB-I to collect substances’ dissolutions in seawater such as hydrocarbons. Deepwater experiments were conducted in Toyama Bay in Japan and enabled demonstration of the ability of SOTAB-I to establish the vertical water column distribution of oceanographic data, such as temperature, salinity, and density. In addition, a high-resolution profile of water currents was obtainable.