Abstract The volcano-hosted geothermal system of Copahue is one of the most promising resources of renewable energy in Argentina. It is driven by a layered reservoir composed of a steam cap above a deep liquid-dominated reservoir. We study the surficial leakages of the shallow steam zone by performing a discrete fracture network model and a 3D forward strain-stress model of the upper caprock unit. The hydrothermal zones linked to steam cap leakages are subordinated to deep-rooted N60-striking faults. Associated damage zones exhibit higher values of fracture intensity, vertical and anisotropy of permeability than the host rocks. Joints and cross-joints likely control leakage zones, where the formers are subject to high dilation tendency. The Anfiteatro monocline might constitute the northwestern boundary of the shallow steam zone. Variations of H2O–CO2 ratio, helium isotopic signature, and CO2 between hydrothermal zones are explained in terms of petrophysical properties of the upper ignimbrites and changes in their structural control. Our results suggest that the upper caprock ignimbrite avoids the decompression of the reservoir because it provides the low fractured and low permeability layer that seals the geothermal system; conversely, ignimbrites affected by the extensional faults system enhance the shallow vapor zone given its high fracture density and permeability.

中文翻译：

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Copahue地热田蒸汽区渗漏的离散裂缝网络模型

摘要 Copahue 火山地热系统是阿根廷最有前景的可再生能源资源之一。它由一个分层的油藏驱动，该油藏由一个深部以液体为主的油藏上方的蒸汽盖组成。我们通过执行离散裂缝网络模型和上盖层单元的 3D 正向应变应力模型来研究浅层蒸汽带的表面泄漏。与蒸汽盖泄漏相关的热液区隶属于根深蒂固的 N60 断层。相关损伤区的裂缝强度、渗透率的垂直和各向异性值高于围岩。接头和交叉接头可能控制泄漏区域，其中前者容易膨胀。Anfiteatro 单斜斜面可能构成浅层蒸汽带的西北边界。H2O-CO2 比率、氦同位素特征和热液带之间 CO2 的变化可以从上部熔凝灰岩的岩石物理性质及其结构控制的变化来解释。我们的研究结果表明，上盖层熔凝岩避免了储层减压，因为它提供了密封地热系统的低裂缝和低渗透层；相反，受伸展断层系统影响的凝灰岩由于其高裂缝密度和渗透率而增强了浅层蒸汽带。我们的研究结果表明，上盖层熔凝岩避免了储层减压，因为它提供了密封地热系统的低裂缝和低渗透层；相反，受伸展断层系统影响的凝灰岩由于其高裂缝密度和渗透率而增强了浅层蒸汽带。我们的研究结果表明，上盖层熔凝岩避免了储层减压，因为它提供了密封地热系统的低裂缝和低渗透层；相反，受伸展断层系统影响的凝灰岩由于其较高的裂缝密度和渗透率而增强了浅层蒸汽带。