Occurrence and saturation of free gas and gas hydrate at complex tectonic and interbedded reservoir in the Hikurangi Margin, New Zealand

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Author(s): Wang Xiujun; Liu Bo
Author Affiliation(s): Primary:
Chinese Academy of Sciences, Institute of Oceanology, Qingdao, China
Volume Title: AGU 2018 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2018; American Geophysical Union 2018 fall meeting, Washington, DC, Dec. 10-14, 2018. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Logging while drilling (LWD) conducted by International Ocean Discovery Program (IODP) Expeditions 372 and seismic data were used to study the occurrence and saturation of free gas and its relationship with gas hydrate in the Northern Hikurangi subduction margin east of New Zealand. Pore-filing gas hydrates were discovered above the bottom simulating reflector (BSR) as inferred from well log and core data at Site 1517. Gas hydrate-bearing sediments showed high resistivity, high P-wave velocity and slightly increased S-wave velocity comparing to the water-saturated sediments above the base of gas hydrate stability zone (BGHSZ). However, interbedded high and low P-wave velocities together with enhanced seismic reflections were observed below BGHSZ indicating the presence of free gas. The gas hydrate and free-gas saturations were estimated and compared based on different models integrating the nuclear magnetic resonance (NMR) and shear wave velocity. The saturations of gas hydrate and free gas are also calculated from seismic data using constraints from LWD data. The variation of saturation has a close relationship with the complex tectonics and fluid flow in the study area.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 02 Geochemistry; Australasia; Expedition 372; Gas hydrates; Geochemistry; Geophysical methods; Geophysical surveys; Hikurangi Margin; IODP Site U1517; International Ocean Discovery Program; New Zealand; Pacific Ocean; Seismic methods; South Pacific; Southwest Pacific; Surveys; Tectonics; West Pacific
Coordinates: S384947 S384947 E1782834 E1782834
Record ID: 2019050444
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