Submarine gas-leakage monitoring system for long-term detection of gas and method of operating the same

A method of operating a submarine gas-leakage monitoring system for long-term detection of gas, the system including:

• a buoy equipped with a satellite communication unit to transmit acquired data to a satellite or to receive a command for activation or inactivation of any of a plurality of first submarine sensors from a satellite when the buoy is raised to float on the seawater surface;
• a seabed observation unit located on a seabed and equipped with a second submarine sensor, the seabed observation unit configured to acquire information about gas leakage from the seabed and to control storage of the information about gas leakage from the seabed and to control raising or lowering of the buoy;
• and
• a signal cable equipped with the first submarine sensors to detect migration or diffusion of leaked gas, the signal cable being connected between the buoy and the seabed observation unit to allow a signal transmission between the buoy and the seabed observation unit,
• the method comprising the steps of:
• (a) storing, for a predetermined period of time, information about leaked gas measured by the second submarine sensor;
• (b) periodically, or when a predetermined condition is satisfied, unwinding the signal cable to raise the submerged buoy to the seawater surface;
• (c) transmitting the data stored in the seabed observation unit to the buoy through the signal cable;
• (d) transmitting the data to the satellite through the satellite communication unit installed in the buoy;
• (e) when data communication with the satellite is finished, winding the signal cable to lower the buoy so that the buoy is submerged,
• (f) when a value detected by the second submarine sensor equals or exceeds a reference value and when the buoy is raised to the seawater surface, repeatedly performing steps (f1) to (f3) to track migration or diffusion of the leaked gas to the seawater surface after performing step (d):
• (f1) by the controller in the seabed observation unit, receive from the satellite the command signal for activation or inactivation of each first submarine sensor,
• (f2) by the controller, control operation of each first submarine sensor,
• (f3) transmit data acquired by the first and second submarine sensor to the satellite via the satellite communication unit;
• and
• (g) when leaked gas is detected by the second submarine sensor and the buoy is raised to the seawater surface, sequentially activating the first submarine sensors.