Thermal properties and thermal structure in the deep-water coalbed basin off the Shimokita Peninsula, Japan
Thermal properties and thermal structure in the deep-water coalbed basin off the Shimokita Peninsula, Japan
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DOI：
10.1016/j.marpetgeo.2016.03.006
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发表时间：
2016-05
影响因子：
4.2
通讯作者：
W. Tanikawa;O. Tadai;S. Morita;Weiren Lin;Yasuhiro Yamada;Y. Sanada;K. Moe;Y. Kubo;F. Inagaki-F.-In
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文献类型：
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作者：
W. Tanikawa;O. Tadai;S. Morita;Weiren Lin;Yasuhiro Yamada;Y. Sanada;K. Moe;Y. Kubo;F. Inagaki-F.-In
热输运性质是影响深部沉积盆地地热过程的重要参数。我们测量了深海沉积物岩心样品的热性质，深度约为2500米以下的海底（mbsf），而大多数以前的研究只提供了数据<800 mbsf的海洋沉积物，从盆地关闭Shimokita，日本在综合大洋钻探计划（IODP）远征337。热导率和热扩散率随深度增加，热容量随深度下降，尽管数据在更深处高度分散。热导率的增加主要是由于沉积过程中固结导致沉积物孔隙度降低。同一岩心剖面上不同岩性的岩石反映了同一深度热导率的高度变化。煤的热导率最低，为0.4 Wm− 1 K −1，方解石胶结砂岩/粉砂岩的热导率最高，约为3 Wm− 1 K −1。其它热物性也受孔隙度和岩性对比度的影响。热导率和孔隙率之间的相关性可以用几何平均值的混合律模型来解释。根据测得的热导率估算的C 0020地点的一维温度-深度剖面显示了温度梯度随深度的回归，并估算了30 mWm−2的表面热流，这与该地点附近的热流数据一致。所获得的结果表明，线性地热梯度估计的平均热导率值在浅沉积物材料可能高估的温度在更大的深度和低估的热流。
Heat transport properties are significant parameters that affect geothermal processes in deep sedimentary basins. We measured the thermal properties of deep sediment core samples to a depth of approximately 2500 m below sea floor (mbsf), whereas most previous studies have only presented data <800 mbsf for marine sediments, taken from the basin off Shimokita, Japan during Integrated Ocean Drilling Program (IODP) Expedition 337. Thermal conductivity and thermal diffusivity increased with depth, and heat capacity decreased with depth, although the data were highly scattered at greater depths. The increase in thermal conductivity is explained primarily by the porosity reduction of sediment resulting from consolidation during sedimentation. The high variations in thermal conductivity at the similar depth are reflected by various lithological rocks formed at the same core section. Coal exhibits the lowest thermal conductivity of 0.4 Wm−1K−1, and calcite-cemented sandstone/siltstone exhibits the highest conductivity of approximately 3 Wm−1K−1. The other thermal properties are also influenced by the porosity and lithological contrast. The correlation between thermal conductivity and porosity is explained by the mixed-law model of the geometric mean.The one-dimensional temperature-depth profile at site C0020 estimated from measured thermal conductivity reveals a regression of the thermal gradient with depth, and the surface heat flow of 30 mWm−2, which is consistent with the heat flow data near this site, was evaluated. The obtained results suggest that the linear geothermal gradient estimated from the average thermal conductivity value at shallow sediment materials could overestimate the temperature at greater depths and underestimate the heat flow.