石油学报 ›› 2013, Vol. 34 ›› Issue (6): 1112-1118.DOI: 10.7623/syxb201306009

• 地质勘探 • 上一篇    下一篇

南海沉积物中天然气水合物饱和度与声学特性的关系

胡高伟1,2,3, 业渝光2,3, 张剑2,3, 刘昌岭2,3, 李清3   

  1. 1. 国土资源部海洋油气资源与环境地质重点实验室 山东青岛 266071;
    2. 国土资源部天然气水合物重点实验室 山东青岛 266071;
    3. 青岛海洋地质研究所 山东青岛 266071
  • 收稿日期:2013-04-16 修回日期:2013-07-15 出版日期:2013-11-25 发布日期:2013-10-13
  • 通讯作者: 业渝光,男,1946年4月生,1970年毕业于天津大学,现为青岛海洋地质研究所研究员和中国海洋大学博士生导师,从事海洋地质学实验研究。Email:yeyug@public.qd.sd.cn
  • 作者简介:胡高伟,男,1982年11月生,2004年毕业于中国地质大学(武汉),2010年获中国地质大学(武汉)博士学位,现为青岛海洋地质研究所助理研究员,从事海洋地质学、天然气水合物方面的研究。Email:hgw-623@163.com
  • 基金资助:

    国家自然科学基金项目(No.41104086,No.40576028)、中国地质调查局百名青年地质英才培养计划和国土资源部海洋油气资源与环境地质重点实验室开放基金(MRE201113)资助。

Relationship between gas hydrate saturation and acoustic properties of sediments in the South China Sea

HU Gaowei1,2,3, YE Yuguang2,3, ZHANG Jian2,3, LIU Changling2,3, LI Qing3   

  1. 1. Key Laboratory of Marine Hydrocarbon Resources & Environmental Geology, Ministry of Land & Resources, Qingdao 266071, China;
    2. Key Laboratory of Gas Hydrate, Ministry of Land & Resources, Qingdao 266071, China;
    3. Qingdao Institute of Marine Geology, Qingdao 266071, China
  • Received:2013-04-16 Revised:2013-07-15 Online:2013-11-25 Published:2013-10-13

摘要:

中国南海蕴藏丰富的天然气水合物(气水合物)资源,研究其赋存区沉积物中气水合物的声学响应特征,对南海气水合物的调查和资源估算具有重要意义。利用新型弯曲元探测技术和套管型时域反射技术(TDR),采用模拟实验手段研究了南海神狐海域沉积物中气水合物形成的声学响应特征,发现在气水合物饱和度(Sh)为0~14% 时,声波信号随气水合物形成而逐渐减弱,而当Sh>14% 后,声波信号渐渐增强;气水合物形成过程中,纵、横波速度(vpvs)随Sh的增加而增大,且vsSh>14% 后增长速度加快。这些现象表明,气水合物在南海沉积物中可能先在孔隙流体中以微粒子的状态生成,对声波造成了较大的散射衰减,导致声波信号变弱,但对剪切模量的贡献不明显;当Sh高于14% 后,微粒子数量的增多使气水合物聚集,并与沉积物颗粒接触,从而加快了vs的增长。

关键词: 天然气水合物, 南海, 声学响应, 弯曲元, 时域反射技术

Abstract:

Gas hydrate has been recognized to be a potential energy resource in the South China Sea (SCS) and the acoustic response of gas hydrate formations in the SCS sediments is of significance in the regional hydrate investigation and quantification. We conducted a simulation experiment to investigate the acoustic response of hydrate formations in the Shenhu area of the SCS using a new bender-element detection technique combined with the casing time-domain reflectometry (TDR). The results showed that the acoustic signal becomes weaker with the occurrence of hydrates as the saturation of hydrates (Sh) ranges from 0 to 14%; then it strengthens gradually as Sh is higher than 14%. The acoustic velocities (vp, vs) of sediments increase with the increase of Sh during hydrate formation and vs increases relatively faster as Sh becomes higher than 14%. These phenomena indicated that hydrates may form firstly in pore fluids in the form of tiny particles, which results in a weaker acoustic signal due to the considerable scattering attenuation of acoustic wave, but has little effect on shear modulus. As time lapses, when Sh exceeds 14%, numerous tiny particles of hydrates coalesce together and contact with sediment particles. As a result, vs has a sharp increase.

Key words: gas hydrate, South China Sea (SCS), acoustic response, bender element, time domain reflectometry (TDR)

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