Hidetaka Senga

Autonomous Spilled Oil and Gas Tracking Buoy System and Application to Marine Disaster Prevention System: Part 1

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 SOTAB-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.

Spilled Oil Tracking Autonomous Buoy System

Spilled oil damages not only the ocean environment but also the regional economy. In order to minimize such damages we are now developing a spilled oil tracking autonomous buoy system. The buoys used in this system are expected to send their location, and the meteorological and oceanographic data around them, to the land base in real-time while they drift with spilled oil. In the case that the buoy detaches from the spilled oil by external forces, it must be capable of detecting and tracking the spilled oil autonomously. In this paper, we first describe the concept of this system. This is followed by the development of two kinds of oil-detecting sensors installed on the buoy: a contact sensor and a non-contact sensor. The efficiencies of these sensors were verified by carrying out various water tank experiments. The buoy tracks spilled oil with descending and ascending procedures by controlling its buoyancy and movable wings. The developed control algorithm was validated with some water tank experiments using a simple buoy model. Finally, we carried out field experiments, such as data measurements and autonomous tracking experiments, using a new buoy model equipped with oil detecting sensors, GPS and an anemometer. The results of field experiments show the efficiency of this system.

Development of Spilled Oil Tracking Autonomous Buoy System

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 algorithm.

Spilled Oil Tracking Autonomous Buoy

We are developing Spilled Oil Tracking Autonomous Buoy System (SOTABS), which is composed of a land base and several spilled oil tracking autonomous buoys (SOTAB), to detect and track spilled oil autonomously, sending real time data around them to the land base. This paper firstly deals with steady sailing performance of SOTAB-II with a sailboat shape for tracking spilled oil on the sea surface by controlling the rudder angle, and the area and direction of the sail, and then sea trials using a model of SOTAB-II with a cylindrical buoy shape to obtain its fundamental characteristics on motion.

Development of Spilled Oil and Gas Tracking and Monitoring Autonomous Buoy System and its Application to Marine Disaster Prevention

In this paper, the recent developments in the ongoing project on spilled oil and gas tracking autonomous buoy system and its application to marine disaster prevention system are described. The objectives of the project mainly consist of (1) autonomous tracking and monitoring of spilled plumes of oil and gas from sub-sea production facilities, (2) autonomous tracking of spilled oil on the sea surface and transmission of useful data to a land station through satellites in real time, (3) improvement of the accuracy of real-time simulations as well as prediction of the diffusion and drifting of spilled oil and gas.

Considerations on of Drillpipe Dynamics with Actual Drilling Data

The scientific drilling vessel CHIKYU was designed to have the capability to drill down to 10000m total vertical depth and to obtain core samples. To reach such deep drilling and to recover core samples, it is important to know drill pipe dynamics using the actual drilling data. The core recovery rate is affected by the variation of the weight on bit caused by the propagation of the vessel heave motions. Therefore, a heave-compensating system will be used and it is very important to evaluate the performance. Furthermore, the drill bit behavior will also influence on the core recovery. In the extreme case, stick-slip, which will cause cracks or fractures in the core samples, occurs. In addition, to reach such deep drilling, a fine strength evaluation is mandatory because there is little margin. So, the estimation of dynamic tension due to vessel heave motions is necessary. Thus, the authors have acquired the drilling data including the vessel motions, the hook load variations and drilling torque variations. It is observed that the heave compensating system have the capability to mitigate the propagation of the vessel heave to the drill string within 30% if the condition is good. On the other hand, it was also observed that the heave compensator operated at a low level of mitigation if the condition is bad. Also we conduct the drill pipe dynamics analysis such as the vertical dynamic motions and the drill bit rotation, and make considerations on the hook load variations and the drill bit behaviors. Actual drilling data provided the worthy information on the drill pipe dynamics. The considerations will be utilized for future operations such as Tohoku Earthquake Drilling Program and NANKAI Trough drilling programs and also for future technical development.

Depth and Altitude Control of an AUV Using Buoyancy Control Device

A new method for depth control was developed for a spilled oil and blow out gas tracking autonomous buoy robot called SOTAB-I by adjusting its buoyancy control device. It is aimed to work for any target depth. The new method relies on buoyancy variation model with a depth that was established based on experimental data. The depth controller was verified at sea experiments in the Toyama Bay in Japan and showed good performance. The method could further be adapted to altitude control by combining the altitude data measured from bottom tracking through a progressive depth control. The method was verified at the sea experiments in Toyama in March 2016 and showed that the algorithm succeeded to bring the robot to the target altitude.

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.

Development of a Robotic Floating Buoy for Autonomously Tracking Oil Slicks Drifting on the Sea Surface (SOTAB-II): Experimental Results

After the 2010 Deepwater Horizon accident, environmental regulations shifted to a more goal-oriented approach that required risk management plans for controlling site-specific risks. The real-time long-term monitoring of spilled oil drifting behavior on the sea surface is essential for decreasing the risk to coastal environments posed by spilled oil. This paper describes an autonomous robotic platform or autonomous surface vehicle (ASV), propelled by wind and water currents for the long-term monitoring of spilled oil on the ocean surface. This paper also describes a sensor-based guidance, navigation, and control system for oil spill tracking by ASV in unsteady and uncertain environments. This paper makes a unique contribution to the literature in proposing a cluster-based decision-making algorithm for sailing the ASV based on a complete scanning history of the area surrounding the vehicle by the oil detection sensor. A Gaussian-based oil cluster filtering algorithm is introduced to identify the largest oil slick patch. The physical constraints of the ASV have been taken into account to allow for the computation of feasible maneuvering headings for sailing to avoid sailing upwind (i.e., in the direction from which the wind is coming). Finally, using neoprene sheets to simulate oil spills, field test experiments are described to validate the operation of the ASV with respect to oil spill tracking using a guidance, navigation, and control system based on onboard sensor data for tracking the artificial oil targets.

Depth Control of AUV Using a Buoyancy Control Device

A new method for depth control was developed for a spilled oil and blow out gas tracking autonomous buoy robot called SOTAB-I by adjusting its buoyancy control device. It is aimed to work for any target depth. The new method relies on buoyancy variation model with depth that was established based on experimental data. The depth controller was verified at sea experiments in Toyama bay in Japan and showed good performance. The method could further be adapted to altitude control by combining the altitude data measured from bottom tracking through a progressive depth control. The method was verified by a simulating program and showed that the algorithm succeeded to bring the robot to the target altitude.