地球物理学进展 ›› 2017, Vol. 32 ›› Issue (3): 1008-1018.doi: 10.6038/pg20170309

所属专题: 青藏高原

• 空间与固体地球物理 • 上一篇    下一篇

青藏高原冻土区天然气水合物地层的岩石物理分析

刘杰, 刘江平, 程飞, 王京, 邓小虎, 刘肖肖, 金聪   

  1. 中国地质大学地球物理与空间信息学院, 地球内部多尺度成像湖北省重点实验室, 武汉 430074
  • 收稿日期:2016-09-23 修回日期:2017-04-25 出版日期:2017-06-20 发布日期:2017-06-20
  • 通讯作者: 刘江平,教授,博士生导师,主要从事环境工程地球物理方面的教学和研究工作.(E-mail:liujp_geop@126.com) E-mail:liujp_geop@126.com
  • 作者简介:刘杰,男,1983年,在站博士后,主要从事水合物岩石物理分析和地震响应特征等方面的研究.(E-mail:ljky2008@126.com)
  • 基金资助:

    中国地质大学(武汉)地球内部多尺度成像湖北省重点实验室开放基金(SMIL-2017-04)和中国地质科学院地球物理地球化学研究所专项资助(WH201207)资助.

Rock physics analysis of the hydrate-bearing sediments in the permafrost region of Qinghai-Tibet plateau

LIU Jie, LIU Jiang-ping, CHENG Fei, WANG Jing, DENG Xiao-hu, LIU Xiao-xiao, JIN Cong   

  1. Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China
  • Received:2016-09-23 Revised:2017-04-25 Online:2017-06-20 Published:2017-06-20

摘要:

为了获得青藏高原冻土区天然气水合物地层的物性特征,采用岩石物理方法进行分析.首先,对青藏高原冻土区DK-1、DK-3和DK-4三个井孔制作了速度密度交会图,并比较了不同岩性水合物地层的差异.其次,基于DK-1和DK-4含水合物粉砂岩层段的测井数据,提取了水合物地层骨架的物性参数,包括纵波速度、横波速度、密度、体积模量和剪切模量.最后,依据水合物地层各主要成分的物性参数,建立了基于K-T方程的岩石物理模型和区分填充模式的岩石物理模型,将两类模型的速度曲线分别与实际地层数据进行了对比,并分析了模型与实际地层的近似程度,发现填充模式Ⅱ的水合物岩石物理模型更符合实际情况.冻土区水合物地层具有速度大、密度小的特征,砂岩水合物地层相比泥岩地层在速度和密度方面更具规律性,DK-4井孔165.80~166.35 m 层段中水合物作为岩石骨架的一部分更能反映其物性特征.

Abstract:

The hydrate-bearing sediments are investigated by the method of rock physics in the permafrost regions of Qinghai-Tibet plateau. First of all, several crossplots of velocity-density are made of the data of velocities and densities in the holes of DK-1,DK-3 and DK-4 in the permafrost regions,so this paper comes to this conclusion that the hydrate-bearing sediments have greater velocity and lower density than the sediments without hydrate.Meanwhile compared with the hydrate-bearing mudstone, the hydrate-bearing sandstone are more regular and homogeneous in aspects of velocity and density. Secondly, based on the log data of hydrate-bearing siltstone segments in the DK-1 (143.40~144.20 m) and DK4 (165.80~166.35 m), the physical properties of matrix are extracted according three-phase, time-average equation. These physical properties contains P-wave velocity, S-wave velocity, density, bulk modulus and shear modulus of matrix in the hydrate siltstone segment. Finally, according to the physical properties of the main components of hydrate-bearing sediments, a type of rock physics models are established in the light of K-T equations, and another type of rock physics models of different hydrate fill-modes are established according to the elastic Modulus equations.This paper respectively compare the velocity curves of both types of rock physics models with actual velocities of hydrate layers,and analyze the difference of rock physics models and the actual hydrate-bearing sediments. It draws a conlusion that the rock physics model of hydrate filling-mode Ⅱ is more realistic to the actual hydrate-bearing sediments than others.The results show the hydrate-bearing sediments have greater velocity and lower density than the sediments without hydrate,and compared with the hydrate-bearing mudstone, the hydrate-bearing sandstone are more regular and homogeneous in aspects of velocity and density. More to the point, the microstructure of segment (165.80~166.35 m) in the hole of DK4 is more likely to the filling-mode Ⅱ by the comparison of velocity curves.

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