Development of Monitoring System on Methane Hydrate Production

Abstract

From 2001, the Japanese government has had a national project, conducted by Research Consortium for Methane Hydrate Resources in Japan, which has been promoting methane hydrate exploitation under the seabed in the deep sea of more than 1000 m depth in Japanese EEZ. This paper briefly describes the development of the monitoring technology, by one of the R&D sub-group of Environmental Impact Assessment Group of the Consortium that is conducted by Engineering Advancement Association of Japan, including both sensor technology and integration technology of the monitoring system in the deep sea on some possible factors which can badly affect to the environment around the methane hydrate production area in the future. Regarding sensor technology, we have had great efforts to develop high-performance sensors for dissolved methane and seafloor displacement, which we thought had not been well developed during our pre-investigation several years ago. As to integration of the total monitoring system, at first, we studied well what items to monitor, how to monitor and how accurate to read. According to the results, we studied the existing related technologies including installation units i.e. mooring type and AUV, electric power supply, data transportation, installation/removal method and so on, so that we could successfully reach some conclusion on total concept of the integrated monitoring system. Based on the concept, we also successfully completed the study on a necessary integrated monitoring system that shall be deployed with the well-developed sensors at the ocean production trial that is planned to carry out in the future.

Progress in Global Gas Hydrate Development and Production as a New Energy Resource

“…Twodimensional (2D) and three dimensional (3D) seismic reflection data acquired in 2001 and 2002 from the Nankai Trough, provided geophysical evidence on gas hydrate accumulation and saturation (Fujii, 2008). The Ministry of Economy, Trade and Industry's (METI's) "Tokai-oki and Kumano-nada" exploratory test wells that were drilled in 2004, served in the acquisition of well logs and core data for the assessment of methane resources (Awashima et al, 2008). An initial full-scale production test was performed in the north slope of the Daini-Atsumi Knoll in the eastern Nankai Trough, Japan in 2013.…”

“…For the first offshore methane production, Japan sent a research group responsible for developing environment monitoring technologies prior to the Nankai Trough field test. Their approach mainly included monitoring sensors (e.g., CH 4 sensors, seabed deformation sensors, and biosensors), an integrated monitoring system, and other auxiliary devices such as power supplies, electric cables, and autonomous underwater vehicles (AUVs) (Awashima et al, 2008). In fact, during the Nankai Trough test, hydrate reservoir temperature and seabed deformation were monitored by an integrated monitoring system consisting of two temperature monitoring wells (Natl.…”

“…As such, it is essential to build monitoring platforms to capture and collect field behaviors of geological risks or hazards in situ (Ryu, 2016). Therefore, future work should focus on developing long-term in situ measurements, such as deploying benthic landers, and further building local seafloor networks that combine OBS, anchor systems, seafloor deformation monitoring systems, and so on that can transmit data to onshore platforms in real time (Awashima et al, 2008). However, a long-term production test required to assess impacts of production on the marine environment, climate, and humans is still in the planning stages.…”

Research on Submarine landslide monitoring and early warning system

“…Domestic and foreign scholars have used side-scan sonar, pressure sensor, acceleration sensor, and other equipment to monitor submarine landslides [13][14][15]. Saito et al [15,16] used acceleration sensors to monitor the sliding velocity of the seabed and calculated the sliding displacement of the seabed. Fabian M et al [17,18] used a triaxial acceleration sensor and an inclinometer to monitor the lateral deformation of the seafloor, while Stenvold and Wallace et al [19,20] used a high-precision manometer to monitor the seafloor pressure, thereby obtaining the seafloor subsidence deformation.…”