scholarly journals Hydrochemical Characteristics and Evolution of Geothermal Fluids in the Chabu High-Temperature Geothermal System, Southern Tibet

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
X. Wang ◽  
G. L. Wang ◽  
H. N. Gan ◽  
Z. Liu ◽  
D. W. Nan
Keyword(s):  
High Temperature ◽  
Research Area ◽  
Geothermal Field ◽  
Geothermal System ◽  
Hydrochemical Characteristics ◽  
Mixing Processes ◽  
Southern Tibet ◽  
Geothermal Waters ◽  
South Central ◽  
Geothermal Fluids

This study defines reasonable reservoir temperatures and cooling processes of subsurface geothermal fluids in the Chabu high-temperature geothermal system. This system lies in the south-central part of the Shenzha-Xietongmen hydrothermal active belt and develops an extensive sinter platform with various and intense hydrothermal manifestations. All the geothermal spring samples collected systematically from the sinter platform are divided into three groups by cluster analysis of major elements. Samples of group 1 and group 3 are distributed in the central part and northern periphery of the sinter platform, respectively, while samples of group 2 are scattered in the transitional zone between groups 1 and 3. The hydrochemical characteristics show that the geothermal waters of the research area have generally mixed with shallow cooler waters in reservoirs. The reasonable reservoir temperatures and the mixing processes of the subsurface geothermal fluids could be speculated by combining the hydrochemical characteristics of geothermal springs, calculated results of the chemical geothermometers, and silica-enthalpy mixing models. Contour maps are applied to measured emerging temperatures, mass flow rates, total dissolved solids of spring samples, and reasonable subsurface temperatures. They indicate that the major cooling processes of the subsurface geothermal fluids gradually transform from adiabatic boiling to conduction from the central part to the peripheral belt. The geothermal reservoir temperatures also show an increasing trend. The point with the highest reservoir temperature (256°C) appears in the east-central part of the research area, which might be the main up-flow zone. The cooling processes of the subsurface geothermal fluids in the research area can be shown on an enthalpy-chloride plot. The deep parent fluid for the Chabu geothermal field has a Cl− concentration of 290 mg/L and an enthalpy of 1550 J/g (with a water temperature of 369°C).

scholarly journals Hydrogeochemical Characteristics and Genesis of Geothermal Water from the Ganzi Geothermal Field, Eastern Tibetan Plateau

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1631
Author(s):  
Fan ◽  
Pang ◽  
Liao ◽  
Tian ◽  
Hao ◽  
...  
Keyword(s):  
High Temperature ◽  
Tibetan Plateau ◽  
Heat Source ◽  
Chloride Concentration ◽  
Geothermal Field ◽  
Geothermal Water ◽  
Helium Isotope ◽  
Geothermal System ◽  
The Tibetan Plateau ◽  
Geothermal Waters

The Ganzi geothermal field, located in the eastern sector of the Himalayan geothermal belt, is full of high-temperature surface manifestations. However, the geothermal potential has not been assessed so far. The hydrochemical and gas isotopic characteristics have been investigated in this study to determine the geochemical processes involved in the formation of the geothermal water. On the basis of δ18O and δD values, the geothermal waters originate from snow and glacier melt water. The water chemistry type is dominated by HCO3-Na, which is mainly derived from water-CO2-silicate interactions, as also indicated by the 87Sr/86Sr ratios (0.714098–0.716888). Based on Cl-enthalpy mixing model, the chloride concentration of the deep geothermal fluid is 37 mg/L, which is lower than that of the existing magmatic heat source area. The estimated reservoir temperature ranges from 180–210 °C. Carbon isotope data demonstrate that the CO2 mainly originates from marine limestone metamorphism, with a fraction of 74–86%. The helium isotope ratio is 0.17–0.39 Ra, indicating that the He mainly comes from atmospheric and crustal sources, and no more than 5% comes from a mantle source. According to this evidence, we propose that there is no magmatic heat source below the Ganzi geothermal field, making it a distinctive type of high-temperature geothermal system on the Tibetan Plateau.

Occurrence of K-feldspar-bearing hydrothermal breccias in the Bouillante geothermal field (Basse Terre – Guadeloupe)

2013 ◽  
Vol 184 (1-2) ◽  
pp. 119-128 ◽  
Author(s):  
Patricia Patrier ◽  
Sylvain Bruzac ◽  
Rebecca Pays ◽  
Daniel Beaufort ◽  
Vincent Bouchot ◽  
...  
Keyword(s):  
High Temperature ◽  
Textural Properties ◽  
Geothermal Field ◽  
Geothermal System ◽  
Geothermal Fluids ◽  
Argillic Alteration ◽  
Geothermal Activity ◽  
Cap Rock ◽  
Stage 1 ◽  
Mixed Layers

Abstract Surficial indicators of recent to present geothermal activity are present around Bouillante (Guadeloupe, French West Indies). Until lately, most mineralogical parageneses identified in this area were typical of low temperature alteration (< 100°C) with the occurrence of dioctahedral aluminous smectites accompanied by zeolites (heulandite-clinoptilolite) ± calcite ± silica ± kaolinite, as an evidence of the cap rock of the geothermal system. Recently, numerous boulders of highly silicified breccias containing high temperature minerals (> 200°C) have been identified in the Bouillante bay (Anse Marsolle). Their petrographic study revealed several hydrothermal parageneses typical of a multistage alteration process. Stage 1) An early potassic alteration facies typical of a high-temperature geothermal system characterized by K-feldspar/adularia + quartz + pyrite. K-feldspars have been shown to be present both in the clasts (replacement) and cement of these breccias. They are associated with quartz whose textural properties have revealed fracturing associated with boiling. Stage 2) An acid-sulphate advanced argillic alteration facies with the occurrence of jarosite, gypsum ± silica (≥ 150°C) as usually observed in the upper part of epithermal systems worldwide as marker of deeper boiling. Stage 3) An argillic alteration facies (illite/smectite mixed layers ± smectite ± calcite). With temperatures typically ranging from 100 to 200°C, this alteration facies is associated with near neutral fluids of mainly meteoric origin as known in the present geothermal reservoir (pH = 5.4). This alteration is the later one as evidenced by petrographic observations. These results highlight mineral assemblages and mineral textures characteristic of high temperature hydrothermal alteration in epithermal settings. The occurrence of these breccias involved the existence of eruptive events (magmatic/hydrothermal explosion) which ejected this material. Isotopic (oxygen, argon) and geochemical (trace elements) studies are now necessary to clarify the timing of these breccias and the nature and the connection of the original fluids with current geothermal fluids

Geophysical investigations of the Cove Fort‐Sulphurdale geothermal system, Utah

Geophysics ◽  
1985 ◽  
Vol 50 (11) ◽  
pp. 1732-1745 ◽  
Author(s):  
Howard P. Ross ◽  
Joseph N. Moore
Keyword(s):  
High Temperature ◽  
Large Scale ◽  
Thermal Anomaly ◽  
Power Production ◽  
Time Frame ◽  
Geothermal Reservoir ◽  
Magnetic Data ◽  
Geothermal System ◽  
Thermal Anomalies ◽  
Geothermal Fluids

The Cove Fort‐Sulphurdale KGRA is part of one of the largest thermal anomalies in the western United States. Since 1975 an extensive data base has been developed which includes the results of detailed and regional geologic, gravity, magnetic, seismic, and resistivity investigations. Geologic studies have delineated the major tectonic elements of the thermal system and have led to the recognition of large‐scale gravitational glide blocks that act as a leaky cap to portions of the geothermal system. Gravity and magnetic data have delineated major throughgoing structures beneath alluvium and basalt cover, and have indicated the importance of the Cove Fort‐Beaver graben in localizing the geothermal reservoir. The presence of these structures and a high level of microearthquake activity suggest other target areas within the larger thermal anomaly. Electrical resistivity surveys and thermal gradient holes both contribute to the delineation of the known reservoir. Four deep exploration wells which test the geothermal system were drilled between 1975 and 1979. One well, CFSU 42–7, recorded temperatures of 178°C. The high cost of drilling, high corrosion rates, low reservoir pressures, and the apparent limited extent of the high‐temperature reservoir led to a premature conclusion in 1980 that the field was not economic for large‐scale electric power production. More recent drilling in the vicinity of CFSU 42–7 resulted in the discovery of high‐temperature (200°C?) geothermal fluids at a depth of approximately 350 m. A well‐head generator was installed and power production is expected in 1985. Additional development of the geothermal reservoir is anticipated in the 1985 to 1987 time frame.

Heat transfer estimation through a high-temperature geothermal field in New Zealand quantified by multi-channel data modelling

2021 ◽  
Author(s):  
Alberto Ardid ◽  
Rosalind Archer ◽  
David Dempsey
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Temperature ◽  
New Zealand ◽  
Geothermal Field ◽  
Heat Fluxes ◽  
Geothermal System ◽  
Geothermal Systems ◽  
Total Heat Flow ◽  
Sustainable Resource Management

<p>In high-temperature geothermal systems, understanding heat transfer helps conceptualize the whole system as well as estimating the resource size. To obtain the fullest picture, it is necessary to integrate different types of data, e.g., surface electromagnetic surveys, wellbore lithology, geochemistry, and temperature logs. This can be achieved through joint modelling. Here, we quantify the spatial distribution of heat transfer through the hydrothermally-altered, impermeable smectite layer that has developed atop the Wairākei-Tauhara geothermal system, New Zealand. Our approach involves first constraining 1D magnetotelluric (MT) inversion models with methylene blue analysis (MeB, an indicator of conductive smectite clay) and mapping these onto temperature and lithology data from geothermal wells. Then, one-dimensional models of heat transfer are fitted to well temperature logs to estimate heat flux variations across the field. We use our integrated method to estimate the average heat flux through the clay cap (2.2 W/m2) and total heat flow (380 ± 21 MW) of the Wairākei-Tauhara geothermal field. This approach models multiple datasets for estimating heat fluxes and could be applied in geothermal provinces around the world with implications for sustainable resource management and our understanding of magmatic systems.</p>

Exploring geothermal resources using active and passive EM methods in the coastal areas of volcanic islands

2021 ◽  
Author(s):  
Simon Védrine ◽  
Pascal Tarits ◽  
Mathieu Darnet ◽  
François Bretaudeau ◽  
Sophie Hautot
Keyword(s):  
High Temperature ◽  
Geothermal Field ◽  
Coastal Areas ◽  
Geothermal System ◽  
Geothermal Resources ◽  
Geothermal Exploration ◽  
Near Surface ◽  
Urbanized Areas ◽  
Transient Electromagnetism ◽  
Volcanic Islands

<p>Electromagnetic geophysical exploration plays a key role in high-temperature geothermal projects to estimate the geothermal potential of a region. The objective of an EM campaign applied to high-temperature geothermal exploration is to obtain an image of the impermeable clay cap, the permeable geothermal reservoir, and the system's heat source at depth, as these three components of the overall geothermal system have distinct electrical signatures. However, deep electromagnetic imaging in the coastal areas of volcanic islands represents a major challenge due to the presence of strong cultural noise induced by urbanized areas concentrated around the coast, the proximity to the sea, strong variations of topography and bathymetry, the small size of targets and the heterogeneity of the near surface. Our objective is the multi-scale integration of airborne transient electromagnetism (ATEM), shallow marine and in land magnetotelluric (MT) and controlled source electromagnetism (CSEM) to improve the reconstruction of deep geological structures by inversion. The contribution of the CSEM method is the key to overcoming cultural electromagnetic noise and exploiting data acquired in urbanized areas. In order to study how to integrate the different EM data, we first apply our methodology to data from a geothermal exploration campaign carried out a few years ago in Martinique in the French West Indies. Then, we present results from runs with synthetic tests for a campaign planned this year in Guadeloupe, also in the French West Indie, whose objective is to increase the production capacity of an existing geothermal field.</p>

scholarly journals Geothermal exploitation in the Sani-Afytos area of the Kassandra peninsula (Chalkidiki peninsula, Northern Greece)

2018 ◽  
Vol 40 (3) ◽  
pp. 1162
Author(s):  
Ch. Kougoulis ◽  
A. Arvanitis ◽  
N. Kolios ◽  
S. Koutsinos ◽  
J. S. Kougoulis
Keyword(s):  
Geothermal Gradient ◽  
Geothermal Field ◽  
Thermal Waters ◽  
Tectonic Structures ◽  
Borehole Data ◽  
Northern Greece ◽  
Geothermal Waters ◽  
Geothermal Exploration ◽  
Average Value ◽  
Geothermal Fluids

The Sani-Afytos area in the Kassandra Peninsula (Chalkidiki) was the area of systematic geothermal exploration. Based on deep oil borehole data, the Paleogene, Neogene and Quaternary sediments show significant thickness reaching 3600 m and cover the metamorphosed Mesozoic, mainly carbonate, basement. The detailed water temperature investigation proved the presence of sub-thermal waters (20-28°C) at depths up to 300 m and the spatial distribution of the isothermal curves at depths of 150 and 200 m according to the main NW-SE and SE-NW tectonic structures of the area. Through the construction of geothermal exploration and production wells at depths of 422-583 m, thermal waters of 31.7-36°C were detected within the Upper Miocene sediments. The average value of the geothermal gradient was calculated to be 3-4°CI 100 m. One production well of 520 m depth provides waters of 34°C while its potential flow rate is approximately 50 m /h. The geothermal waters were classified in Na-HCOi and Na-CI types of waters with TD. S 0.89-2.03 g/l. With the aid of chemical geothermometers the deep temperature was estimated to be 80-100°C. In one exploration well, the presence of gas phase (77% v/v CH4, 21.8% v/v N2) was detected. The geothermal exploration resulted in the characterization of the area as the "geothermal field of Sani-Afytos" and in the prospective development using the geothermal fluids in the tourism and other activities.

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