Geological setting and characterization of a methane hydrate reservoir distributed at the first offshore production test site on the Daini-Atsumi Knoll in the eastern Nankai Trough, Japan
Geological setting and characterization of a methane hydrate reservoir distributed at the first offshore production test site on the Daini-Atsumi Knoll in the eastern Nankai Trough, Japan
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DOI：
10.1016/j.marpetgeo.2015.02.037
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发表时间：
2015-09-01
影响因子：
4.2
通讯作者：
Nagao, Jiro
中科院分区：
文献类型：
--
作者：
Fujii, Tetsuya;Suzuki, Kiyofumi;Nagao, Jiro
为了获得位于南海海槽东部第二厚海丘西北坡的第一个海上生产试验场（AT1）的甲烷水合物（MH）储层特征的基本信息，2012年使用混合压力取心系统在监测井（AT1-MC）和取心井（AT1-C）进行了广泛的地球物理测井和压力取心。 AT1-MC地球物理测井证实，MH浓集带（MHCZ）具有60米厚的浊积岩组合，其亚层厚度从几十到几百厘米不等。浊积岩组合由上部的叶片状层序和下部较厚的河道砂层序组成。两口相距40 m以内的监测井砂层井间对比显示，油藏上部砂层横向连续性较好。这为生产测试提供了一个理想的储层。通过与压力岩心分析评估的结果进行比较，证实了根据地球物理测井数据评估的MH孔隙饱和度（S-h）的有效性。在 MHCZ 的上部，与核磁共振 (NMR) 测井的 S-h 值相比，由电阻率测井估算的 S-h 值显示出砂层和泥层之间存在明显差异。电阻率测井比核磁共振测井具有更高的垂直分辨率；因此，它们有利于这些类型的薄层评估。在上部，沙层中观察到的S-h值为50%-80%，这与岩心得出的S-h值相当吻合。在 MHCZ 的下部，从电阻率和 NMR 测井估算的 S-h 值显示出比上部更高的背景值和相对平滑的曲线。在下部砂层中也观察到了50%-80%的S-h值，与岩心导出的S-h值表现出良好的一致性。 (C) 2015 年作者。由爱思唯尔有限公司出版
To obtain basic information for methane hydrate (MH) reservoir characterization at the first offshore production test site (AT1) located on the northwestern slope of the Daini-Atsumi Knoll in the eastern Nankai Trough, extensive geophysical logging and pressure coring using a hybrid pressure coring system were conducted in 2012 at a monitoring well (AT1-MC) and a coring well (AT1-C). The MH-concentrated zone (MHCZ), which was confirmed by geophysical logging at AT1-MC, has a 60-m-thick turbidite assemblage with sublayers ranging from a few tens to hundreds of centimeters thickness. The turbidite assemblage is composed of lobe/sheet-type sequences in the upper part and relatively thick channel-sand sequences in the lower part. Well-to-well correlations of sandy layers between two monitoring wells within 40 m of one another exhibited fairly good lateral continuity of sand layers in the upper part of the reservoir. This suggests an ideal reservoir for the production test.The validity of MH pore saturation (S-h) evaluated from geophysical logging data were confirmed by comparing with those evaluated by pressure core analysis. In the upper part of the MHCZ, S-h values estimated from resistivity logs showed distinct differences between the sand and mud layers, compared with S-h values from nuclear magnetic resonance (NMR) logs. Resistivity logs have higher vertical resolution than NMR logs; therefore, they are favorable for these types of thin-bed evaluations. In the upper part, S-h values of 50%-80% were observed in sandy layers, which is in fairly good agreement with core-derived S-h values. In the lower part of the MHCZ, S-h values estimated from both resistivity and NMR logs showed higher background values and relatively smoother curves than those for the upper part. In the lower part, S-h values of 50%-80% were also observed in sandy layers, and they showed good agreement with the core-derived S-h values. (C) 2015 The Authors. Published by Elsevier Ltd.