Characteristics of gas chimneys and their implications on gas hydrate accumulation in the Shenhu area, northern south China sea
Characteristics of gas chimneys and their implications on gas hydrate accumulation in the Shenhu area, northern south China sea
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DOI：
10.1016/j.jngse.2020.103629
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发表时间：
2020-12
影响因子：
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通讯作者：
Cong Cheng;T. Jiang;Z. Kuang;Chengzhi Yang;Cheng Zhang;Yunlong He;Zhe Cheng;D. Tian;Peng X
中科院分区：
文献类型：
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作者：
Cong Cheng;T. Jiang;Z. Kuang;Chengzhi Yang;Cheng Zhang;Yunlong He;Zhe Cheng;D. Tian;Peng X
天然气水合物作为一种潜在的替代能源，已引起世界各国学者的广泛关注。2017年，广州海洋地质调查局在深湖地区成功开展了天然气水合物开采试验，这对中国地区天然气水合物研究具有相当重要的意义。神狐地区天然气垂直运移的主要途径是以二维地震资料为基础的几项研究。本研究以2018年新采集的高分辨率三维地震资料为基础，结合2007年和2015年探险期间的测井资料，确定了天然气烟囱对天然气水合物聚集的贡献。结果识别出4种不同顶部形状的气体烟囱，其内部地震反射特征自下而上以混沌、声学消隐和高振幅反射为主。此外，在一些天然气烟囱上方发现了厚厚的水合物层。通过对白云凹陷油气生成和构造沉积演化的进一步分析，认为白云凹陷天然气烟囱的演化可分为五个阶段。此外，作为神狐地区天然气垂向运移的主要通道，天然气烟囱可来源于文昌组和恩平组，并可侵入第四系天然气水合物储集层。这导致深层热成气直接向上运移到天然气水合物稳定带(GHSZ)，并聚集到烟囱顶部或上方的厚厚水合物层中。
Gas hydrates have captivated extensive concentration from scholars all over the world as potential alternative energy sources. In 2017, the Guangzhou Marine Geological Survey (GMGS) carried out a successful gas hydrate production test in the Shenhu area, which was of considerable significance to the study of gas hydrates in China. Several studies describing gas chimneys as the primary vertical gas migration pathways in the Shenhu area were mainly based on two-dimensional (2D) seismic data. In this research, on the basis of high-resolution three-dimensional (3D) seismic data newly acquired in 2018, combined with well logging data acquired during the 2007 and 2015 expeditions, the contribution of gas chimneys to gas hydrate accumulation was determined. As a result, four types of gas chimneys with various top shapes were identified, and their internal seismic reflection characteristics were predominantly chaotic, acoustic blanking, and high-amplitude reflection from bottom to top. Moreover, thick hydrate layers were discovered above some of the gas chimneys. Further analyses on the hydrocarbon generation and tectono-sedimentary evolution in the Baiyun Sag indicated the evolution of gas chimneys could be divided into five stages. Furthermore, as the primary vertical gas migration pathways in the Shenhu area, gas chimneys could be sourced from the Wenchang formation and Enping formation and could pierce into the Quaternary gas hydrate reservoirs. This resulted in deep thermogenic gas directly migrating upward into the gas hydrate stability zone (GHSZ) and accumulating into thick hydrate layers on or above the top of gas chimneys.