Geologic controls on supercritical geothermal resources above magmatic intrusions.
Geologic controls on supercritical geothermal resources above magmatic intrusions.
复制标题
DOI：
10.1038/ncomms8837
复制
发表时间：
2015-07-27
影响因子：
16.6
通讯作者：
Weis P
中科院分区：
文献类型：
--
作者：
Scott S;Driesner T;Weis P
最近在冰岛克拉夫拉火山系统中发现了一种新型且具有经济吸引力的地热资源，该资源由 2 公里深岩浆体正上方 450°C 的超临界水组成。尽管利用此类超临界资源可以使地热井的发电量成倍增加，但类似资源的丰度、位置和规模尚不清楚。在这里，我们首次对超临界地热资源形成进行了数值模拟，表明它们是岩浆驱动的地热系统的组成部分。潜在的可开采资源形成于脆韧转变温度高于 450°C 的岩石中，例如玄武岩。水温和热函可超过 400°C 和 3MJkg−1，具体取决于宿主岩石的渗透性。传统的高焓资源是由上升的超临界水和较冷的周围水混合产生的。我们的模型再现了克拉夫拉发现的资源的测量热条件。类似的资源可能广泛存在于传统的高热函地热系统之下。 利用超临界地热水可以增加能源产量，但此类资源的丰富程度、位置和规模尚不清楚。在这里，作者提出了数值模拟，并表明超临界水可能在消除所有岩浆侵入体的热量方面发挥着关键作用。
A new and economically attractive type of geothermal resource was recently discovered in the Krafla volcanic system, Iceland, consisting of supercritical water at 450 °C immediately above a 2-km deep magma body. Although utilizing such supercritical resources could multiply power production from geothermal wells, the abundance, location and size of similar resources are undefined. Here we present the first numerical simulations of supercritical geothermal resource formation, showing that they are an integral part of magma-driven geothermal systems. Potentially exploitable resources form in rocks with a brittle–ductile transition temperature higher than 450 °C, such as basalt. Water temperatures and enthalpies can exceed 400 °C and 3 MJ kg−1, depending on host rock permeability. Conventional high-enthalpy resources result from mixing of ascending supercritical and cooler surrounding water. Our models reproduce the measured thermal conditions of the resource discovered at Krafla. Similar resources may be widespread below conventional high-enthalpy geothermal systems. Utilizing supercritical geothermal water could multiply energy production, but the abundance, location and size of such resources is unclear. Here, the authors present numerical simulations and suggest that supercritical water may play a key role in removing heat from all magmatic intrusions.