Equilibrium halite-H2O dihedral angles: High rock-salt permeability in the shallow crust?
Equilibrium halite-H2O dihedral angles: High rock-salt permeability in the shallow crust?
复制标题
平衡石盐-H2O二面角：浅地壳中岩盐渗透率高？
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
M. Holness
中科院分区：
文献类型：
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作者：
Stephanie Lewis;M. Holness
众所周知，浅层盐岩矿床对卤水和碳氢化合物是不渗透的，但最近对深埋盐的研究指向相当大的水-盐岩相互作用。我们通过实验测定了(静态)盐岩-H2O体系在20~300℃和大气压至2kbar的压力下的二面角，解决了这个明显的悖论。控制孔隙-流体连通性和渗透率的盐岩-卤水二面角被发现是温度和压力的敏感函数。在具有正常地温梯度的沉积盆地中，深度超过3公里的盐岩岩体将含有稳定的相互连通的充满卤水的孔隙度，因此渗透率可与砂岩相当。我们的结果解释了最近在深部观察到的主要盐液相互作用，并表明根深蒂固的盐底辟可能是盆地地层水的管道。它们还对埋藏在天然岩盐中的高放射性核废料的产热罐周围的盐水流动有重要影响。
Shallow deposits of halite are well known to be impermeable to brines and hydrocarbons, yet recent studies of deeply buried salt point toward considerable water-halite interaction. We have resolved this apparent paradox via experimental determinations of the dihedral angle for the (static) halite-H 2 O system at temperatures of 20 to 300 °C and pressures from atmospheric to 2 kbar. The halite-brine dihedral angle, which controls pore-fluid connectivity and hence permeability, is found to be a sensitive function of both temperature and pressure. In sedimentary basins with normal geothermal gradients, halite bodies at depths exceeding 3 km will contain a stable interconnected brine-filled porosity, resulting in permeabilities comparable to those of sandstones. Our results explain recent observations of major salt-fluid interactions at depth, and suggest that deep-rooted salt diapirs may act as conduits for basinal formation water. They also have important implications for the flow of brines around heat-producing canisters of high-level nuclear waste buried in natural rock salt.