Japan Geoscience Union Meeting 2023

Presentation information

[J] Online Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS18] Gas hydrates in environmental-resource sciences

Tue. May 23, 2023 10:45 AM - 12:15 PM Online Poster Zoom Room (21) (Online Poster)

convener:Hitoshi Tomaru(Department of Earth Sciences, Chiba University), Shinsuke Aoki(The National Institute of Advanced Science and Technology)

On-site poster schedule(2023/5/22 17:15-18:45)

10:45 AM - 12:15 PM

[MIS18-P03] Wireline logging results of methane hydrate reservoir of off Joetsu in the Japan Sea

*Kiyofumi Suzuki1, Hideyoshi Yoshioka1, Mikio Satoh1, CK22-03C Shipboard Scientific Party (1.National Institute of Advanced Industrial Science and Technology)

Keywords:Gas hydrate, Wireline logging, Chlorinity

The research of the deep marine surface-methane hydrate in the National Institute of Advanced Industrial Science and Technology (AIST) was started as the resource survey to grasp the amount of their volume since 2013 to 2015, then, until 2018, the feasibility study of how to develop it had been studied. Since 2019, R&D have been progressed as the trinity of the production method development, resource survey for production test, and evaluation of environment effect. Especially in this phase, we have started the geomechanical study of surface methane-hydrate bearing sediments at 2 area of methane hydrate reservoirs. One of them was the research campaign at the off-Joetsu area using D/V Chikyu struggled in 2022 September, was successfully done finally, and many sediment core samples and wireline logging results, such as sonic, nuclear-magnetic resonance , resistivity, density and sigma, were gathered.
At the campaign, we drilled 2 holes in 2 site, the methane hydrate site and reference site, Joetsu knoll and Umitaka spur. Result of drilling, we knew that the base of gas hydrate stability zone (BGHSZ) at hole of Joetsu knoll site is 106mBSF, and that of Umitaka spur site is 96mBSF, seemingly. These depth are shallow than the estimated BGHSZ from geothermal gradient around the area, so we would like to consider the reasons. The resistivity below the BGHSZ is 0.1[ohm.m], stably in both site. The gas hydrate saturation varies from 0 to 100% in depth, which is corresponded with resistivity, partialy, i.e. it is considered that the non-corresponded depth could be anomaly of resistivity. On the basis of the neutron capture cross-section controlled by chloride, we calculated the salinity from sigma values from logging, we will discuss the structures and properties of surface methane hydrate reservoir in presentation.
This study was conducted as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).