Structural control of the graben fault on hydrothermal alteration in the Cerro Pabellón geothermal system (Andean Cordillera, Northern Chile)

IF 2.9 2区地球科学 Q3 ENERGY & FUELS

Geothermal Energy Pub Date : 2023-06-29 DOI:10.1186/s40517-023-00260-8

J. Vidal, P. Patrier, D. Beaufort, S. Maza, G. Rivera, G. Volpi, D. Morata

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引用次数: 1

Abstract

This study focuses on hydrothermal alteration in the geothermal reservoir of Cerro Pabellón (Andean Cordillera, Northern Chile). It is based on CP2A and CP5A production wells drilled above a local normal fault and presenting unlike hydraulic properties. Cuttings from 300 to 1555 m depth were sampled and analyzed using X-ray diffraction (XRD) to observe distribution of hydrothermal minerals and crystal chemistry variations of clays (fraction < 5 μm). Then, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM–EDX) allowed to perform microanalysis of hydrothermal minerals. These results highlight a mineral assemblage that was not observed before, composed of adularia + Ba-rich feldspar + feathery quartz + chalcedony + calcium arsenates + illite. They are characteristics of high-temperature hydrothermal alteration in epithermal settings and are restricted to shallow permeable fracture zones of the active part of the reservoir. Another fracture-controlled event related to a typical illitization is observed in all permeable fracture and fault zones of the geothermal system. This multi-event alteration seems strongly controlled by the eastern graben fault and the associated interconnected fracture network.

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智利北部安第斯山脉Cerro Pabellón地热系统地堑断裂对热液蚀变的构造控制

本文主要研究了智利北部安第斯山脉Cerro Pabellón地热储层的热液蚀变。它是基于CP2A和CP5A生产井，钻在局部正断层上，具有不同的水力性质。利用x射线衍射仪(XRD)对300 ~ 1555 m深度的岩屑进行了取样分析，观察了热液矿物的分布和粘土(分数< 5 μm)的晶体化学变化。然后，扫描电子显微镜结合能量色散光谱(SEM-EDX)可以进行热液矿物的微观分析。这些结果突出了一个以前未观察到的矿物组合，由adularia +富ba长石+羽状石英+玉髓+砷酸钙+伊利石组成。它们是低温热液蚀变的特征，并且局限于储层活动部分的浅层渗透裂缝带。在地热系统的所有渗透性裂缝和断裂带中都观察到另一个与典型非石化有关的裂缝控制事件。这种多事件蚀变似乎受东部地堑断裂及其相关的互联断裂网的强烈控制。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Geothermal Energy Earth and Planetary Sciences-Geotechnical Engineering and Engineering Geology

CiteScore

5.90

自引率

7.10%

发文量

审稿时长

8 weeks

期刊介绍： Geothermal Energy is a peer-reviewed fully open access journal published under the SpringerOpen brand. It focuses on fundamental and applied research needed to deploy technologies for developing and integrating geothermal energy as one key element in the future energy portfolio. Contributions include geological, geophysical, and geochemical studies; exploration of geothermal fields; reservoir characterization and modeling; development of productivity-enhancing methods; and approaches to achieve robust and economic plant operation. Geothermal Energy serves to examine the interaction of individual system components while taking the whole process into account, from the development of the reservoir to the economic provision of geothermal energy.