A new approach for the identification of gas hydrate in marine sediments
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ORIGINAL RESEARCH PAPER
A new approach for the identification of gas hydrate in marine sediments Dongmei Tian1 · Xuewei Liu1 Received: 2 January 2020 / Accepted: 12 August 2020 © The Author(s) 2020
Abstract It has always been the focus of researchers to accurately identify gas hydrate location. Geophysical prospecting is a widely used method for gas hydrate exploration, which has high credibility, especially seismic exploration technology is most generally used. In our study, we analyze the different physical properties of gas hydrate and other minerals bearing in unconsolidated marine sediments based on the effective medium theory. Then, a new attribute is put forward to discriminate gas hydrate. The logging data in the Dongsha area of the South China Sea and the Hydrate Ridge along the Oregon continental margin are applied to validate this method. Our test results are basically in line with actual situation, which provides a new approach in hydrate identification. Keywords Gas hydrate identification · Effective medium theory · Logging data · Marine sediments
Introduction Gas hydrate is regarded as a promising new energy natural resources in the twenty-first century by scientists. It has the advantages of high energy, extensive distribution, large scale, shallow burial and so on (Kvenvolden 1993; Ojha et al. 2010). The reserves of gas hydrate may be 2 times that of the total of gas, oil and coal we known. Many countries have carried out a lot of exploration and experiment study of gas hydrate for decades, such as America, Japan, Canada, etc. Researches show gas hydrate in land area is found only in the lower part of the permafrost area, in contrast the amount of gas hydrate in sea area is very large (Collett et al. 2009; Sloan 2003). Due to the limitation of temperature and pressure, the formation and distribution of gas hydrate in marine sediments are diversified and complex (Cook et al. 2010). Hence, accurately exploring the location
* Xuewei Liu [email protected] Dongmei Tian [email protected] 1
China University of Geosciences (Beijing), School of Geophysics and Information Technology, No. 29 Xueyuan Street, Haidian District, Beijing 100083, People’s Republic of China
of gas hydrate is challenging, which has been widely concerned by researchers. There are various exploration methods of gas hydrate, for example, geophysical techniques, geochemistry techniques (Edwards 1997, 2005; Latychev and Edwarrds 2003), geomorphic survey (Kvenvolden and Kastner 1990), underwater imaging survey (Milkov et al. 2003) and so on. At present, seismic identification techniques are still the most effective and practical exploration method in general use. Bottom simulating reflectors (BSR) is an important symbol to identify gas hydrate in seismic profiles, which are approximately parallel to the seafloor, opposite to the polarity of seabed reflector and are usually accompanied by blank zones (Shipley et al. 1979). However, sometimes BSR may not be present where the hydrate occurs. Therefore, in some cases, it is har
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