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| An experimental study of the capability of shallow seismic method in detecting the frozen soil thickness in permafrost region |
| XU Jian-Yu1, 2, JIANG Chun-Xiang1, 2, YUE Hang-Yu1, 2, WANG Kai1, 2, 3 |
1.Institute of Geophysical and Geochemical Exploration,CAGS,Langfang 065000,China;
2.National Modern Geological Exploration Technology Research Center,Langfang 065000,China;
3.College of GeoExploration Science and Technology,Jilin University,Changchun 130026,China |
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Abstract As the cover of natural gas hydrate deposits in terrestrial permafrost region,the distribution of natural gas hydrate is closely related to the permafrost.It is a new attempt to find the natural gas hydrate by means of seismic method.In order to detect frozen soil effectively,the authors used the method of seismic reflection with small group distance,small shot interval,small offset and high coverage because the permafrost thickness is relatively thin in permafrost region of the Tibetan Plateau.Due to the large difference between the velocities of unconsolidated sedimentary strata with and without freezing,the thickness of frozen soil layer can be reliably detected by analyzing seismic velocity spectrum and reflections reformed by frozen bottom interface.Although the velocity difference of the strata with and without freezing is relatively small for low porosity hard rock sedimentary strata,the impedance difference between the upper and lower strata of the frozen bottom interface will cause the normal reflections to be disturbed and discontinuous.The thickness of the hard rock sedimentary frozen strata can be explained according to the seismic velocity spectrum and the discontinuous disturbance of the tilted reflections.
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Received: 08 September 2017
Published: 20 December 2017
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