| 摘要: |
| 印度国家天然气水合物计划（NGHP01）于2016年实施第1次钻探，证实了天然气水合物在印度大陆边缘的广泛分布。选择位于克里希纳-戈达瓦里盆地（KG盆地）的NGHP01-07D和NGHP01-15A钻孔，基于测井数据和岩心样品估算天然气水合物饱和度，分析天然气水合物赋存状态并探讨其形成机制。基于各向同性介质模型利用电阻率和声波测井计算NGHP01-15A钻孔的天然气水合物饱和度为0.2%~33.0%，平均值为9.6%，在NGHP01-07D钻孔利用电阻率计算获得的天然气水合物饱和度高于岩心氯离子异常和气体释放获得的结果，但是基于各向同性岩石物理模型利用声波测井计算的天然气水合物饱和度与岩心结果一致，平均值为5.0%。前人研究认为NGHP01-10D钻孔中天然气水合物以相对较高饱和度富集在高角度裂隙中。结合前人研究结果推断在克里希纳戈达瓦里盆地存在3种不同的天然气水合物储层，即泥岩中砂质夹层各向同性储层、泥质/粉砂质高角度低连通性的低饱和度裂隙储层和泥岩中高角度高连通性的高饱和度裂隙储层，并提出对应的3种天然气水合物储层模型。 |
| 关键词: 海洋地质学 天然气水合物 储层 饱和度 测井 克里希纳 戈达瓦里盆地（KG盆地） |
| DOI：10.3969/J.ISSN.2095-4972.2019.03.001 |
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| 基金项目:国家自然科学基金资助项目(41576066)；海南省重点研发计划资助项目（ZDYF2018189） |
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| Characteristics of gas hydrate saturations in Krishna Godavari Basin, India |
| KONG Xiu,LI Qi,JIANG Xiao-hong,ZHANG Can-ying |
| (1.Institute of Deepsea Science and Engineering, CAS, Sanya 572000, China;2.China University of Geoscience, Beijing 100083, China; 3.Institute of Oceanology, CAS, Qingdao 266071, China) |
| Abstract: |
| The presence of gas hydrate was confirmed by drillings on the Indian continental margin during the Indian National Gas Hydrate Program Expedition 01 (NGHP01) in 2016. In this paper, Holes NGHP01-15A and NGHP01-7D in KrishnaGodavari Basin were selected to estimate the gas hydrate saturation used logging data and core samples to analyze the geomorphologies of gas hydrate and to infer their evolution mechanisms. At Hole NGHP01-15A, the gas hydrate saturations estimated from resistivity and sonic logs assumed the isotropic medium model are 0.2%~33.0% with an average of 9.6%. At Hole NGHP01-7D, the gas hydrate saturations estimated from resistivity log are higher than those from the abnormal chloride concentrations and coring degassing, while the gas hydrate saturations estimated from sonic log based on isotropic rock physic model are comparable to those estimated from core samples, which is 5.0% on average. The gas hydrate is highly saturated in the high angle fractures at Hole NGHP01-10D according to the previous study. Combined with the previous study,three distinct types of gas hydrate reservoirs can be assumed in KG Basin, i.e. isotropic reservoirs in sands interbedded within shale, high angle low conductive fractured reservoirs with low saturation in silt/shale, and high angle conductive fractured reservoirs with high saturation in shale. Three models corresponding to three types of reservoirs are proposed to illustrate different gas hydrate formation processes. |
| Key words: marine geology gas hydrate reservoir saturation well log Krishna Gadavari (KG) Basin |
