| Focused fluid flow in the Baiyun Sag, northern South China Sea: implications for the source of gas in hydrate reservoirs | |
| Chen Duanxin1,2; Wu Shiguo1; Dong Dongdong1; Mi Lijun3; Fu Shaoying4; Shi Hesheng5; Wu, SG | |
| 2013 | |
| 发表期刊 | CHINESE JOURNAL OF OCEANOLOGY AND LIMNOLOGY
 |
| ISSN | 0254-4059 |
| 卷号 | 31期号:1页码:178-189 |
| 文章类型 | Article |
| 摘要 | The origin and migration of natural gas and the accumulation of gas hydrates within the Pearl River Mouth Basin of the northern South China Sea are poorly understood. Based on high-resolution 2D/3D seismic data, three environments of focused fluid flow: gas chimneys, mud diapirs and active faults have been identified. Widespread gas chimneys that act as important conduits for fluid flow are located below bottom simulating reflections and above basal uplifts. The occurrence and evolution of gas chimneys can be divided into a violent eruptive stage and a quiet seepage stage. For most gas chimneys, the strong eruptions are deduced to have happened during the Dongsha Movement in the latest Miocene, which are observed below Pliocene strata and few active faults develop above the top of the Miocene. The formation pressures of the Baiyun Sag currently are considered to be normal, based on these terms: 1) Borehole pressure tests with pressure coefficients of 1.043-1.047; 2) The distribution of gas chimneys is limited to strata older than the Pliocene; 3) Disseminated methane hydrates, rather than fractured hydrates, are found in the hydrate samples; 4) The gas hydrate is mainly charged with biogenic gas rather than thermogenic gas based on the chemical tests from gas hydrates cores. However, periods of quiet focused fluid flow also enable the establishment of good conduits for the migration of abundant biogenic gas and lesser volumes of thermogenic gas. A geological model governing fluid flow has been proposed to interpret the release of overpressure, the migration of fluids and the formation of gas hydrates, in an integrated manner. This model suggests that gas chimneys positioned above basal uplifts were caused by the Dongsha Movement at about 5.5 Ma. Biogenic gas occupies the strata above the base of the middle Miocene and migrates slowly into the gas chimney columns. Some of the biogenic gas and small volumes of thermogenic gas eventually contribute to the formation of the gas hydrates.; The origin and migration of natural gas and the accumulation of gas hydrates within the Pearl River Mouth Basin of the northern South China Sea are poorly understood. Based on high-resolution 2D/3D seismic data, three environments of focused fluid flow: gas chimneys, mud diapirs and active faults have been identified. Widespread gas chimneys that act as important conduits for fluid flow are located below bottom simulating reflections and above basal uplifts. The occurrence and evolution of gas chimneys can be divided into a violent eruptive stage and a quiet seepage stage. For most gas chimneys, the strong eruptions are deduced to have happened during the Dongsha Movement in the latest Miocene, which are observed below Pliocene strata and few active faults develop above the top of the Miocene. The formation pressures of the Baiyun Sag currently are considered to be normal, based on these terms: 1) Borehole pressure tests with pressure coefficients of 1.043-1.047; 2) The distribution of gas chimneys is limited to strata older than the Pliocene; 3) Disseminated methane hydrates, rather than fractured hydrates, are found in the hydrate samples; 4) The gas hydrate is mainly charged with biogenic gas rather than thermogenic gas based on the chemical tests from gas hydrates cores. However, periods of quiet focused fluid flow also enable the establishment of good conduits for the migration of abundant biogenic gas and lesser volumes of thermogenic gas. A geological model governing fluid flow has been proposed to interpret the release of overpressure, the migration of fluids and the formation of gas hydrates, in an integrated manner. This model suggests that gas chimneys positioned above basal uplifts were caused by the Dongsha Movement at about 5.5 Ma. Biogenic gas occupies the strata above the base of the middle Miocene and migrates slowly into the gas chimney columns. Some of the biogenic gas and small volumes of thermogenic gas eventually contribute to the formation of the gas hydrates. |
| 关键词 | Gas Hydrate Thermogenic Gas Biogenic Gas Dongsha Movement Focused Fluid Flow South China Sea |
| 学科领域 | Marine & Freshwater Biology ; Oceanography |
| DOI | 10.1007/s00343-013-2075-5 |
| URL | 查看原文 |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS研究方向 | Marine & Freshwater Biology ; Oceanography |
| WOS类目 | Limnology ; Oceanography |
| WOS记录号 | WOS:000313654000020 |
| WOS关键词 | POLYGONAL FAULT SYSTEMS ; PEARL RIVER MOUTH ; MID-NORWEGIAN MARGIN ; CONTINENTAL-MARGIN ; MARINE-SEDIMENTS ; BASIN ; ORIGIN ; SLOPE ; GEOCHEMISTRY ; MECHANISM |
| WOS标题词 | Science & Technology ; Life Sciences & Biomedicine ; Physical Sciences |
| 引用统计 | |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://ir.qdio.ac.cn/handle/337002/16334 |
| 专题 | 海洋生物分类与系统演化实验室 |
| 通讯作者 | Wu, SG |
| 作者单位 | 1.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao 266071, Peoples R China 2.Chinese Acad Sci, Grad Univ, Beijing 100049, Peoples R China 3.CNOOC, Explorat Dept, Beijing 100010, Peoples R China 4.Guangzhou Marine Geol Survey, Guangzhou 510760, Guangdong, Peoples R China 5.CNOOC, Shenzhen Branch, Shenzhen 518067, Peoples R China |
| 第一作者单位 | 中国科学院海洋研究所 |
| 推荐引用方式 GB/T 7714 | Chen Duanxin,Wu Shiguo,Dong Dongdong,et al. Focused fluid flow in the Baiyun Sag, northern South China Sea: implications for the source of gas in hydrate reservoirs[J]. CHINESE JOURNAL OF OCEANOLOGY AND LIMNOLOGY,2013,31(1):178-189. |
| APA | Chen Duanxin.,Wu Shiguo.,Dong Dongdong.,Mi Lijun.,Fu Shaoying.,...&Wu, SG.(2013).Focused fluid flow in the Baiyun Sag, northern South China Sea: implications for the source of gas in hydrate reservoirs.CHINESE JOURNAL OF OCEANOLOGY AND LIMNOLOGY,31(1),178-189. |
| MLA | Chen Duanxin,et al."Focused fluid flow in the Baiyun Sag, northern South China Sea: implications for the source of gas in hydrate reservoirs".CHINESE JOURNAL OF OCEANOLOGY AND LIMNOLOGY 31.1(2013):178-189. |
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