Discrete fracture network model of the vapor zone leakages at the Copahue geothermal field

Barcelona, Hernán; Maffucci, Roberta; Yagupsky, Daniel; Senger, Martin; Bigi, Sabina

doi:10.1016/j.jsg.2020.104155

Cited by 10 publications

(5 citation statements)

References 94 publications

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“…The AF and CC hydrothermal zones, located closer to the volcanic edifice, are spatially 516 associated with shallower sets of NE-SW-and NW-SE-oriented normal faults respectively 517 (Melnick et a., 2006;Lamberti et al, 2019;Barcelona et al, 2020). These shallower sets of faults 518 likely represent the escape route for the hydrothermal fluids exsolved from the shallow magmatic 519 reservoir (Lundgren et al, 2017), presenting a lower 3 He/ 4 He ratio.…”

Section: Fluid Circulation Model At Copahue 479mentioning

confidence: 99%

“…The area has been 59 studied extensively over the last thirty years, and, in the early 1990s, the Japanese International 60 Cooperation Agency (JICA) carried out a deep drilling campaign and a feasibility study for 61 developing a high-enthalpy geothermal field. Renewed interest in studying the processes 62 controlling this hypothermal system was driven by the anomalous volcanic unrest of the Copahue 63 volcano during the 2012-2016 period and by the possibility of developing potential geothermal 64 resources in the Andean region (Barcelona et al, 2020). In recent years, several studies have 65 focused on the geochemistry of the Copahue volcanic-hydrothermal system and its CO2 surface 66…”

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confidence: 99%

“…3 1. INTRODUCTION 48 Barcelona et al, 2019;2020) -which affect the ignimbrites of the Las Mellizas volcanic sequence 95 (JICA, 1992; Barcelona et al, 2020). Five active geothermal zones are recognized within the area, 96 with evident surface manifestations consisting of hot springs, boiling pools, bubbling pools, and 97 mud pools with temperatures of up to 96°C, and fumaroles that reach temperatures of up to 135°C 98 (Agusto et al, 2013).…”

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Structural control on shallow hydrogeochemical processes at Caviahue-Copahue Volcanic Complex (CCVC), Argentina

Tardani

Roulleau

Pinti

et al. 2021

Journal of Volcanology and Geothermal Research

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The Caviahue-Copahue Volcanic Complex (CCVC) hosts one of Argentina's most 25 important geothermal systems. To provide new insights into origin, circulation, and residence time 26 of fluids, the chemical and isotopic composition ( 3 He/ 4 He, δ 2 H-δ 18 O in H2O; δ 13 C-δ 18 O in CO2; 27 87 Sr/ 86 Sr) of thermal waters was measured together with the 3 H and 14 C activities. Water samples 28 were collected from hot springs (LM, TC, LMM, CB and AF) representing the five major thermal 29 zones of the CCVC and assumed to be steam-heated meteoric waters, and a well condensate (COP-30 2). The LMM, CB, and AF chemical composition and 87 Sr/ 86 Sr ratios show that water chemistry is 31 acquired locally from exchange with volcanic rocks (Sr, SiO2, among others) and from steam (H2S). 32 Two surface geothermal manifestations (LM and TC), along with the well condensate, COP-2, 33 contain a higher contribution of deep-originating fluids, with 87 Sr/ 86 Sr indicating possible 34 contribution from deep-seated granitoids or sediments from the underlying basement. 35Radiocarbon-based residence times indicate ages ranging between 13,540 and 17,520 yrs BP, 36 representing the minimum age for the geothermal reservoir waters. Tritium is mainly absent in hot 37 spring waters except for LMM and CB where the activity is close to the detection limit. This 38 indicates a minimum age older than 70 yrs for the water circulating in the shallow circuit. This 39 result suggests that shallow meteoric water have a more complex and/or deeper circuit, resulting 40 in older residence times. Helium isotopes in the CCVC span a wide range, from a pure mantle-41 derived value, of 8.35Ra, to a more crustal radiogenic signature, of 4.6Ra. The spatial variation is 42 explained by associating the geochemical data with the geological context, which includes the 43 distribution of fault-fracture meshes and different sources of magmatic volatiles underlying the 44Copahue volcano. The first order control on helium isotope signatures observed in this study seems 45 to be dominated by the degree of crustal assimilation of the magmatic sources, which is in turn 46 controlled by the local arrays of faults.The Copahue stratovolcano, part of the Caviahue-Copahue Volcanic Complex (CCVC), is 49 an active volcano that hosts a high-enthalpy geothermal system (JICA, 1992) that represents a 50 promising resource for geothermal energy in Argentina (Barcelona et al., 2020). The CCVC is 51 located in the Southern Volcanic Zone (SVZ, 33 -46 ° S) of the Andes, at the northern termination 52 of the intra-arc, strike-slip, Liquiñe-Ofqui Fault System (LOFS). Here, a trans-tensional-NE 53 transfer zone is developed, linking the LOFS and the Antiñir-Copahue Fault System (e.g. Sielfeld 54 et al, 2017).The geothermal area of interest lies to the north and northwest of the Copahue volcanic 56 edifice, with several surface emissions including fumaroles, bubbling pools, mud pools and thermal 57 springs, which are spatially associated with local extensional faults which act as fluid p...

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Section: Fluid Circulation Model At Copahue 479mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Structural control on shallow hydrogeochemical processes at Caviahue-Copahue Volcanic Complex (CCVC), Argentina

Tardani

Roulleau

Pinti

et al. 2021

Journal of Volcanology and Geothermal Research

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“…The Copahue geothermal system has been developed at the northeastern part of the Copahue volcano (Figure 1). It mainly extends over the Copahue Village Fault System, composed of a set of extensional N o 60 striking faults developed in a structural block between the Trolope and Chancho-có WNW striking faults (Barcelona et al, 2019;Barcelona et al, 2020;Tardani et al, 2021). This fault architecture (NE and WNW-striking faults) and the complex interaction between them seems to control the permeability and pathways of the hydrothermal fluids/meteoric water and the magma storage beneath the Caviahue Caldera (Barcelona et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

One decade of b-value variations from volcano-tectonic seismicity as an early indicator of episodes of crisis in a volcano: the case of Copahue, Southern Andes

Farías,

Lazo,

Basualto

et al. 2023

Front. Earth Sci.

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Volcanoes can enter in episodes of unrest, which might end later in an eruption, with little warning. They are normally produced due to the inner dynamics of the volcano, but can also be triggered by external earthquakes. To detect these periods early, it becomes crucial to understand the dynamics of the different structures (such as fault systems) of the volcano, as they can act as magma pathways and can also generate instabilities on it. In this article we study the seismicity of Copahue (central-south Chile), which sits atop a complex system of faults, and was importantly affected by the 2010 Mw 8.8 Maule earthquake. We focused ourselves in the temporal variations of the b-value of the Gutenberg-Richter law during the 2012–2022 period. During this timeframe the volcano had a series of crises, which led to seven eruptive phases. Our results show that the system does exhibit signs of a future unrest phase weeks to months before there is a change on its alert level, and they are mostly linked to the activity of a N-S fault zone, located not beneath the main crater of Copahue, but around 10 km to the East. Most of the crises start after drops in the b-value of this structure, with sudden variations in b-value being also noticeable as a response to the 2015 Mw 8.3 Illapel earthquake. Our results show a correlation between instances of fluid injection and release in the relevant structures of an active volcano with the variations of the b-value. This allow us to use the temporal variations of the b-value as a tool to anticipate the inner dynamics of the system, particularly when there is a strong structural control on it, such as in the case of Copahue. We also found out that the influence of the 2010 Mw 8.8 Maule earthquake was long-lived, affecting mostly the structures that later destabilized the volcano for the most part of a decade, therefore enhancing magma injection into the whole system. This seems to have changed since 2021, which might indicate a waning in the influence of the megathrust earthquake in Copahue volcano.

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“…Discrete fracture network (DFN) models are commonly used to describe fracture networks. It uses deterministic or stochastic methods to generate a series of discrete fracture patches in order to quantitatively describe the size, strike, and strength of the fractures (Pan et al, 2019a;Barcelona et al, 2020;Giuffrida et al, 2020). The number of fractures in the reservoir is large, and the fractures range from a few microns to tens of meters, which cannot be simply described in a deterministic manner.…”

Section: Introductionmentioning

confidence: 99%

Fracture Characteristics and Reservoir Inhomogeneity Prediction of the Gaoyuzhuang Formation in the Xiong’an New Area: Insights From a 3D Discrete Fracture Network Model

Yue

Wang

et al. 2022

Front. Earth Sci.

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The Xiong’an new area in northern China is rich in geothermal resources. The Gaoyuzhuang Formation in the Proterozoic Jixian system is an important recently discovered geothermal reservoir. The Gaoyuzhuang reservoir has been affected by multiple stages of tectonic movement. The fractures are very well developed, resulting in strong heterogeneity in the reservoir’s porosity and permeability. Few studies have been conducted on the fractures and heterogeneity of the Gaoyuzhuang reservoir. In this study, interpretation of data from image logs was used to summarize the characteristics of the fractures, including the fractures’ strikes, dips, and lengths. The permeability distribution of the reservoir in the vicinity of the borehole was predicted. The hydro-thermal (TH) coupling model was used to reproduce the process of pumping tests, and the simulation results were found to be in good agreement with the field test data. In addition, the relationship between the fracture aperture and length was obtained, dmax=4.2×10−5⋅L0.5. The results of this study provide data and technical support for further reservoir research and evaluation of the geothermal resources of the Gaoyuzhuang reservoir.

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Discrete fracture network model of the vapor zone leakages at the Copahue geothermal field

Cited by 10 publications

References 94 publications

Structural control on shallow hydrogeochemical processes at Caviahue-Copahue Volcanic Complex (CCVC), Argentina

Structural control on shallow hydrogeochemical processes at Caviahue-Copahue Volcanic Complex (CCVC), Argentina

One decade of b-value variations from volcano-tectonic seismicity as an early indicator of episodes of crisis in a volcano: the case of Copahue, Southern Andes

Fracture Characteristics and Reservoir Inhomogeneity Prediction of the Gaoyuzhuang Formation in the Xiong’an New Area: Insights From a 3D Discrete Fracture Network Model

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