4-Component seismic survey in the first offshore production test of methane hydrate
Abstract
JOGMEC conducted a gas production test in the offshore field where methane hydrates exist in the first offshore production test in March 2013. 4-component seismic survey was carried out as geophysical monitoring to assess the dissociation behaviour of methane hydrates by comparing the characteristics of seismic data before and after the gas production test. The data acquisition was performed three times using an ocean bottom cable (OBC), which installed on the sea bottom of 1000m water depth around the gas production well, consists of 36 receiver devices at an interval of 26.5 meters. The first data acquisition was performed in August 2012 before the gas production test. The second and final data acquisitions were performed in April and August 2013 after the gas production test respectively. The shooting operations using air gun source were executed in 2D lines along OBC and in pseudo 3D layout. The OBC was not collected, a connection with a recording boat was disconnected, the terminal of the OBC was waterproofed, and it had been left in the survey area after the first and the second data acquisitions. The terminal of the OBC installing on the sea bottom was fished and the OBC was reconnected into the recording boat before the second and the final data acquisitions. The OBC had been left on the sea bottom for 8 months and 4 months respectively, but the OBC could work normally and provided high quality data. In the result of the analysis of the acquired data, the change in physical properties and the decrease in impedance were seen by the data comparison before and after the gas production test, and the result which suggests dissociation of methane hydrates was obtained. In addition, the increase phenomenon of impedance from the second to the final data acquisition was seen, which suggests a possibility of the regeneration of methane hydrates.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMNS23A1928K
- Keywords:
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- 0920 Gravity methods;
- EXPLORATION GEOPHYSICSDE: 0925 Magnetic and electrical methods;
- EXPLORATION GEOPHYSICSDE: 0935 Seismic methods;
- EXPLORATION GEOPHYSICSDE: 0999 General or miscellaneous;
- EXPLORATION GEOPHYSICS