Abstract
Marine gas hydrates accumulate primarily in coarse-grained, high-permeability layers; however, highly saturated natural gas hydrates have been discovered in the fine-grained sediments of Shenhu area, South China Sea (SCS). This may be explained by key factors, such as the great abundance of foraminifera shells. In this paper, by analyzing the SCS foraminifera structure and performing hydrate formation experiments in the foraminifera shells, the contribution of foraminifera to hydrate accumulation in the SCS was investigated from a microscopic point of view. Simulations of hydrate formation were carried out in both pure SCS foraminifera shells and the host sediments. Pore structures in typical foraminifera were studied by use of micro-focus X-ray computed tomography (CT) and scanning electron microscopy (SEM). Hydrate growth and occurrence characteristics in the foraminifera shells were observed in-situ. The results showed that the presence of foraminifera significantly enhanced the effective porosity of the SCS sediments. Moreover, while the hydrates grew preferentially in the chambers of the coarse-grained foraminifera by adhering to the inner walls of the foraminifera shells, no apparent hydrate accumulation was observed in the fine-grained or argillaceous matrix. These findings provide a basis for further studies on the accumulation mechanism of hydrates and physical properties of hydrate reservoir in the South China Sea.
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References
Bahk J J, Um I K, Holland M. 2011. Core lithologies and their constraints on gas-hydrate occurrence in the East Sea, offshore Korea: Results from the site UBGH1-9. Mar Pet Geol, 28: 1943–1952
Bahk J J, Kim D H, Chun J H, Son B K, Kim J H, Ryu B J, Torres M E, Riedel M, Schultheiss P. 2013. Gas hydrate occurrences and their relation to host sediment properties: Results from Second Ulleung Basin gas hydrate drilling expedition, East Sea. Mar Pet Geol, 47: 21–29
Best A I, Priest J A, Clayton C R I, Rees E V L. 2013. The effect of methane hydrate morphology and water saturation on seismic wave attenuation in sand under shallow sub-seafloor conditions. Earth Planet Sci Lett, 368: 78–87
Chen F, Su X, Zhou Y, Lu H F, Liu G H, Zhen Z X, Chen C Y. 2009. Variations in biogenic components of late Miocene-holocene sediments from Shenhu area in the northern South China Sea and their geological implication. Mar Geol Quat Geol, 29: 1–8
Chen F, Zhou Y, Su X, Liu G H, Lu H F, Wang J L. 2011. Gas hydrate saturation and its relation with grain size of the hydrate-bearing sediments in the Shenhu area of northern South China Sea. Mar Geol Quat Geol, 31: 95–100
Chen F, Su X, Lu H F, Zhou Y, Zhuang C. 2013. Relations between biogenic component (Foraminifera) and highly saturated gas hydrates distribution from Shenhu area, Northern South China Sea. Earth Sci, 38: 907–915
Hill T. 2004. High-resolution records of methane hydrate dissociation: ODP Site 893, Santa Barbara Basin. Earth Planet Sci Lett, 223: 127–140
Hill T M, Kennett J P, Valentine D L. 2004. Isotopic evidence for the incorporation of methane-derived carbon into foraminifera from modern methane seeps, Hydrate Ridge, Northeast Pacific. Geochim Cosmochim Acta, 68: 4619–4627
Hu G W, Ye Y G, Zhang J, Liu C L, Diao S B, Wang J S. 2010. Acoustic properties of gas hydrate-bearing consolidated sediments and experimental testing of elastic velocity models. J Geophys Res, 115: B02102
Hu G W, Li C F, Ye Y G, Liu C L, Zhang J, Diao S B. 2014. Observation of gas hydrate distribution in sediment pore space. Chin J Geophys, 57: 1675–1682
Li C F, Hu G W, Ye Y G, Liu C L, Cheng J, Zhang L K, Zheng R E. 2013. Microscopic distribution of gas hydrate in sediment determined by X-ray computerized tomography. J Optoelectron Laser, 23: 551–556
Li Q, Wang J, Chen J, Wei Q. 2010. Stable carbon isotopes of benthic foraminifers from iodp expedition 311 as possible indicators of episodic methane seep events in a gas hydrate geosystem. Palaios, 25: 671–681
Li Q, Wang J S, Cai F, Chen Q, Hu G W. 2011. Carbon and oxygen stable isotopes of benthic foraminifera as possible indicators of episodic methane seeps in gas hydrate geo-system—A study from IODP expedition 311. Mar Geol Front, 27: 29–36
Liu C, Ye Y, Meng Q, He X, Lu H, Zhang J, Liu J, Yang S. 2012. The characteristics of gas hydrates recovered from Shenhu Area in the South China Sea. Mar Geol, 307–310: 22–27
Panieri G, Aharon P, Sen Gupta B K, Camerlenghi A, Ferrer F P, Cacho I. 2014a. Late Holocene foraminifera of Blake Ridge diapir: Assemblage variation and stable-isotope record in gas-hydrate bearing sediments. Mar Geol, 353: 99–107
Panieri G, James R H, Camerlenghi A, Westbrook G K, Consolaro C, Cacho I, Cesari V, Cervera C S. 2014b. Record of methane emissions from the West Svalbard continental margin during the last 23500 yrs revealed by δ13C of benthic foraminifera. Glob Planet Change, 122: 151–160
Ren S R, Liu Y, Liu Y, Zhang W. 2010. Acoustic velocity and electrical resistance of hydrate bearing sediments. J Petroleum Sci Eng, 70: 52–56
Su X, Song C B, Fang N Q. 2005. Variation in grain size of sediments above BSR and correlation with the occurrence of gas hydrates on Hydrates Ridge, East Pacific. Earth Sci Front, 12: 234–242
Waite W F, Santamarina J C, Cortes D D, Dugan B, Espinoza, D N, Germaine J, Jiang J, Jung J W, Kneafsey T J, Shin H, Soga K, Winters W J, Yun T S. 2009. Physical properties of hydrate-bearing sediments. Rev Geophys, 47: RG4003
Wang H B, Yang S X, Wu N Y, Zhang G X, Liang J Q, Chen D F. 2013. Controlling factors for gas hydrate occurrence in Shenhu area on the northern slope of the South China Sea. Sci China Earth Sci, 56: 513–520
Wang J S, Gao Y Y, Li Q, Yang C Q, Chen Q, Wei Q, Wang X Q, Hu G W. 2007. Grain size constraint on gas hydrate occurrence: Evidence from sediment size during IODP 311. Adv Earth Sci, 22: 659–665
Wang X J, Hutchinson D R, Wu S G, Yang S X, Guo Y Q. 2011. Elevated gas hydrate saturation within silt and silty clay sediments in the Shenhu area, South China Sea. J Geophys Res, 116: B0102
Winters W J, Pecher I A, Waite W F, Mason D H. 2004. Physical properties and rock physics models of sediment containing natural and laboratoryformed methane gas hydrate. Am Mineral, 89: 1221–1227
Xiang R, Liu F, Chen Z, Yan W, Chen M H. 2010. Recent progress in cold seep benthic foraminifera. Adv Earth Sci, 25: 193–202
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Li, C., Hu, G., Zhang, W. et al. Influence of foraminifera on formation and occurrence characteristics of natural gas hydrates in fine-grained sediments from Shenhu area, South China Sea. Sci. China Earth Sci. 59, 2223–2230 (2016). https://doi.org/10.1007/s11430-016-5005-3
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DOI: https://doi.org/10.1007/s11430-016-5005-3