Constraints on fluid flow pathways from shear wave splitting in and around an active fluid-escape structure: Scanner Pockmark, North Sea

Author:

Robinson A H1,Bayrakci G2,Macdonald C3,Minshull T A1,Bull J M1,Chapman M3,Henstock T J1,Callow B14

Affiliation:

1. School of Ocean and Earth Science, University of Southampton , Southampton SO17 1BJ , UK

2. National Oceanography Centre , European Way, Southampton SO14 3ZH , UK

3. School of Geosciences, University of Edinburgh , Edinburgh EH93JW , UK

4. Department of Geology, Ghent University , B-9000 Gent , Belgium

Abstract

SUMMARY Vertical fluid-escape structures observed in seismic reflection data represent an important class of potentially active fluid flow pathways. An understanding of the mechanism of fluid flow in these types of structures is needed to assess the risk of natural gas venting from potential subsurface carbon dioxide storage operations. The Scanner Pockmark Complex is a 22 m deep, 900 × 450 m seabed depression in the North Sea, which actively vents methane, and is underlain by a seismic chimney structure with horizontal dimensions of ∼300 × 600 m. Gas accumulation is evidenced by the presence of bright reflectors at the top of this seismic chimney, at a depth of ∼50 m below the seabed. Here, we analyse seismic anisotropy in these shallow sediments using shear wave splitting observed on ocean bottom seismographs (OBS). Anisotropy varies spatially, with a strength of ∼1–4 per cent, on several OBS located in and around the pockmark complex. By correlating these observations with calculated subsurface P- and S-wave velocities, we show that there is anisotropy present throughout the sediments through which the chimney passes, which are interpreted as relating to syn- and post-depositional glaciomarine processes. However, within the chimney itself the orientation of the fast direction is different to that outside the chimney and the degree of anisotropy is lower. We attribute this difference as indicating that the anisotropy observed within the chimney is associated with the formation and continued presence of the gas migration system, which overprints the background depositional anisotropy.

Funder

Natural Environment Research Council

European Union

Publisher

Oxford University Press (OUP)

Subject

Geochemistry and Petrology,Geophysics

Cited by 2 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3