Influence of foraminifera on formation and occurrence characteristics of natural gas hydrates in fine-grained sediments from Shenhu area, South China Sea

作     者：LI ChengFeng HU GaoWei ZHANG Wei YE YuGuang LIU ChangLing LI Qing SUN JianYe 

作者机构：Key Laboratory of Gas Hydrate Ministry of Land and Resources Qingdao Institute of Marine Geology Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and Technology College of Information and Control Engineering China University of Petroleum 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2016年第59卷第11期

页      面：2223-2230页

核心收录：

学科分类：070903[理学-古生物学与地层学(含：古人类学)] 081803[工学-地质工程] 0709[理学-地质学] 07[理学] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 41506082, 41474119, 41376078, 41306065 & 41306062) the Scientific and Technological Innovation Project Financially Supported by Qingdao National Laboratory for Marine Science and Technology (Grant No. 2015ASKJ03) 

主　　题：Shenhu area Foraminifera Gas hydrate Occurrence characteristics X ray computed tomography 

摘      要：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.