Journal articles: 'High enthalpy geothermal reservoirs'

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Wang, X., G. L. Wang, H. N. Gan, Z. Liu, and D. W. Nan. "Hydrochemical Characteristics and Evolution of Geothermal Fluids in the Chabu High-Temperature Geothermal System, Southern Tibet." Geofluids 2018 (2018): 1–15. http://dx.doi.org/10.1155/2018/8532840.

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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).

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Trota, Ferreira, Gomes, Cabral, and Kallberg. "Power Production Estimates from Geothermal Resources by Means of Small-Size Compact Climeon Heat Power Converters: Case Studies from Portugal (Sete Cidades, Azores and Longroiva Spa, Mainland)." Energies 12, no. 14 (July 23, 2019): 2838. http://dx.doi.org/10.3390/en12142838.

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Renewable forms of energy are increasingly penetrating the electricity market, particularly, geothermal energy. A wide range of resource temperatures and fluid quality are converted mostly using traditional binary power plants and, recently, using Climeon modular units. Portuguese natural geothermal resources are far from precise estimations. Despite the parameter uncertainties, electric power resource estimations of two natural geothermal reservoirs are presented: a volcanic sourced heated high-enthalpy geothermal reservoir in Sete Cidades, São Miguel Island, Azores; and a low-enthalpy geothermal reservoir linked to a fractured zone in a granitic setting in Longroiva, in the northern part of the Portuguese mainland. Based on the volumetric method, we assessed the power potential of geothermal resources in Sete Cidades and Longroiva using a probabilistic methodology—Monte Carlo simulation. The average reserve estimations for Climeon module were 5.66 MWe and 0.64 MWe for Sete Cidades and Longroiva, respectively. This figure was by far higher when compared to traditional binary technology; those differences were mostly attributed to distinct conversions efficiency factors.

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Grippi, Jamie. "Reviewing the relationship between thermal reservoir parameters and geothermal energy output." PAM Review Energy Science & Technology 5 (May 31, 2018): 2–21. http://dx.doi.org/10.5130/pamr.v5i0.1494.

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This meta-study draws upon contemporary literature to examine parameters of thermal reservoirs and their relationships to geothermal power station output metrics. The objectives of the meta-study are to identify trends and quantify the influence of each parameter on the system as a whole. This study provides a framework for industry and researchers exploring new potential geothermal fields. Six reservoir parameters – well depth, temperature, enthalpy, mass flow rate, thermal gradient and crust thickness – were plotted against the net electrical output per production well (Enet/well) and exergy efficiency (ηB) of 64 geothermal facilities. The meta-study identified that reservoir temperature has the greatest proportionality to power output, with yields above 10MWe exhibited only for high enthalpy reservoirs exceeding 500K. Well depth has the greatest inverse proportionality to exergy efficiency, with upper limit values declining below 80% for wells deeper than 3000m. Well depth has a similar trend line, though lesser correlation, as reservoir temperature to power output. Crust thickness has an inverse correlation to exergy efficiency, with upper limit values dropping from 100% to 65% as thickness increased from 30 to 45km. There was significant clustering of data points in most trendless plots, suggesting a considerable degree of homogeneity between currently tapped reservoirs and turbine efficiencies. The low number of well-defined data trends implies a high degree of complexity arising from the relationships between reservoir parameters that make quantification problematic. Despite this difficulty, examination of the aforementioned parameters suggests that although hotter reservoirs are usually found at greater depths, the hottest and shallowest reservoirs should be prioritized for use in order to return maximal power outputs and reduce exergy losses that occur along large lengths of piping.

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Yadav, Kriti, and Anirbid Sircar. "REVIEW OF DEEP DRILLING TECHNIQUES FOR HIGH ENTHALPY GEOTHERMAL RESERVOIRS." International Journal of Advanced Research 5, no. 6 (June 30, 2017): 2359–70. http://dx.doi.org/10.21474/ijar01/4681.

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Elders, W. A., D. Nielson, P. Schiffman, and A. Schriener Jr. "Investigating ultra high-enthalpy geothermal systems: a collaborative initiative to promote scientific opportunities." Scientific Drilling 18 (December 22, 2014): 35–42. http://dx.doi.org/10.5194/sd-18-35-2014.

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Abstract. Scientists, engineers, and policy makers gathered at a workshop in the San Bernardino Mountains of southern California in October 2013 to discuss the science and technology involved in developing high-enthalpy geothermal fields. A typical high-enthalpy geothermal well between 2000 and 3000 m deep produces a mixture of hot water and steam at 200–300 °C that can be used to generate about 5–10 MWe of electric power. The theme of the workshop was to explore the feasibility and economic potential of increasing the power output of geothermal wells by an order of magnitude by drilling deeper to reach much higher pressures and temperatures. Development of higher enthalpy geothermal systems for power production has obvious advantages; specifically higher temperatures yield higher power outputs per well so that fewer wells are needed, leading to smaller environmental footprints for a given size of power plant. Plans for resource assessment and drilling in such higher enthalpy areas are already underway in Iceland, New Zealand, and Japan. There is considerable potential for similar developments in other countries that already have a large production of electricity from geothermal steam, such as Mexico, the Philippines, Indonesia, Italy, and the USA. However drilling deeper involves technical and economic challenges. One approach to mitigating the cost issue is to form a consortium of industry, government and academia to share the costs and broaden the scope of investigation. An excellent example of such collaboration is the Iceland Deep Drilling Project (IDDP), which is investigating the economic feasibility of producing electricity from supercritical geothermal reservoirs, and this approach could serve as model for future developments elsewhere. A planning committee was formed to explore creating a similar initiative in the USA.

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Pluymaekers, M. P. D., L. Kramers, J. D. van Wees, A. Kronimus, S. Nelskamp, T. Boxem, and D. Bonté. "Reservoir characterisation of aquifers for direct heat production: Methodology and screening of the potential reservoirs for the Netherlands." Netherlands Journal of Geosciences - Geologie en Mijnbouw 91, no. 4 (December 2012): 621–36. http://dx.doi.org/10.1017/s001677460000041x.

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AbstractGeothermal low enthalpy heat in non-magmatic areas can be produced by pumping hot water from aquifers at large depth (>1 km). Key parameters for aquifer performance are temperature, depth, thickness and permeability. Geothermal exploration in the Netherlands can benefit considerably from the wealth of oil and gas data; in many cases hydrocarbon reservoirs form the lateral equivalent of geothermal aquifers. In the past decades subsurface oil and gas data have been used to develop 3D models of the subsurface structure. These models have been used as a starting point for the mapping of geothermal reservoir geometries and its properties. A workflow was developed to map aquifer properties on a regional scale. Transmissivity maps and underlying uncertainty have been obtained for 20 geothermal aquifers. Of particular importance is to take into account corrections for maximum burial depth and the assessment of uncertainties. The mapping of transmissivity and temperature shows favorable aquifer conditions in the northern part of the Netherlands (Rotliegend aquifers), while in the western and southern parts of the Netherlands aquifers of the Triassic and Upper Cretaceous / Jurassic have high prospectivity. Despite the high transmissivity of the Cenozoic aquifers, the limited depth and temperature reduce the prospective geothermal area significantly.The results show a considerable remaining uncertainty of transmissivity values, due to lack of data and heterogeneous spatial data distribution. In part these uncertainties may be significantly reduced by adding well test results and facies parameters for the map interpolation in future work. For underexplored areas this bears a significant risk, but it can also result in much higher flowrates than originally expected, representing an upside in project performance.

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Ardakani, Elahe P., and Douglas R. Schmitt. "Geothermal energy potential of sedimentary formations in the Athabasca region, northeast Alberta, Canada." Interpretation 4, no. 4 (November 1, 2016): SR19—SR33. http://dx.doi.org/10.1190/int-2016-0031.1.

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The Athabasca region, located in the northeast of Alberta, Canada, hosts many ongoing projects of bitumen extraction from oil sands and Devonian carbonate and siliciclastic reservoirs, which require a vast amount of thermal energy. Geothermal energy as a green renewable source of heat can help to reduce the amount of fossil fuels used to provide the required thermal energy for these projects and consequently decrease the greenhouse gas emission. To assess the geothermal development potential in this region, an integrated regional-scale 3D model was constructed with geologic and geophysical data (approximately 7000 formation tops and approximately 800 km seismic 2D profiles). Incorporation of 2D seismic profiles that filled in the gaps between sparse geologic tops particularly for deeper formations adds to structural details of the modeled formations. The temperature and porosity fields were simulated using the sequential Gaussian simulation approach within the modeled sedimentary formations. Based on spatial distribution, thickness, formation porosity and permeability analysis, five Paleozoic formations of Keg River, Waterways, Cooking Lake, Leduc, and Grosmont were identified as potential aquifers for geothermal development. These aquifers have enough coverage and thickness in the area and possess a high amount of thermal energy content. Because the sedimentary basin in the Athabasca region is quite shallow (less than 1400 m), these aquifers are all recognized as low enthalpy geothermal reservoirs with maximum of 40°C temperature and hence direct heating applications are not feasible. Use of industrial-scale heat-pump technologies that have long been used in northern Europe with high coefficients of performance would be recommended for heat extraction from these reservoirs.

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Dwinanto, Ariya, and Sudjati Rachmat. "Aerated Underbalance Drilling Screening Assessment at “X” Geothermal Field." KnE Energy 1, no. 1 (December 1, 2015): 22. http://dx.doi.org/10.18502/ken.v1i1.339.

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Fault network is a challenging problem for geothermal drilling operations. Formation fluid contains high temperature production fluid which can reach >225oC on high enthalpy system. The other consequences is that almost all fault network has low pressure or subnormal pressure. This low pressure results to a loss circulation problem. This low pressure can even go lower if the geothermal field has been exploited for a long period. A miss reservoir management, that do not re-inject sufficient amount of fluid, will cause the reservoir pressure go lower. Another problem in Indonesia is the conservation area which almost all high enthalpy geothermal system exist. The pay zone that is beneath the conservation area must be reached by directional drilling as a solution. High temperature fluid, low formation pressure and conservation areas are problems for geothermal drilling. To overcome these problems, underbalance drilling method has an advantage dealing with low pressure reservoir. This paper introduces a way to screen the underbalance drilling method on a certain field. This study will help the quantitative and qualitative decision whether the underbalance drilling is feasible or not. The first phase qualitative decision is based on wellbore stability, loss circulation, reservoir damage, stuck pipe incident, hard drilling and cost benefit. Then it will go to the drilling fluid decision. And at the end as a quantitative decision for constructing a feasible bottom hole pressure window area with some hole cleaning assessment. Underbalance drilling assessment will be studied on field “X” at one of Indonesia’s geothermal field. The screening of “X” geothermal field comes with conclusions that it has an opportunity underbalance drilling can be implemented with vertical aerated drilling wells on spesific gas and liquid flow rates. Keywords: Geothermal, underbalance drilling, aerated drilling

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Menezes, Paulo T. L., Jandyr M. Travassos, Adriano J. A. Marçal, and Fernando A. Monteiro Santos. "3D magnetotelluric exploration of Sete Cidades Volcano, São Miguel Island, Azores." Interpretation 5, no. 2 (May 31, 2017): T219—T230. http://dx.doi.org/10.1190/int-2016-0018.1.

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Geothermal energy accounts for 43% of the electricity expenditure of São Miguel Island, Azores Archipelago. All production comes from the Ribeira Grande (RG) high-enthalpy geothermal field. To meet the growing energy demand in the island, it is necessary to extend the exploration efforts to new areas. We evaluated the results of a broadband magnetotelluric reconnaissance survey conducted at Sete Cidades Volcano, placed only 30 km westward of the RG field. The resistivity structure of the Sete Cidades geothermal system was obtained through a simultaneous 3D inversion of the full impedance tensor and tipper. The bathymetry and the topography of the island were treated as fixed features in the model. The geothermal reservoir at Sete Cidades is outlined as a northwest–southeast elongated resistive anomaly, geologically controlled by the Terceira Rift fracture zone. We have also identified high-conductivity zones between 1000 and 4000 m below mean sea level, probably associated with clay cap rocks overlying the geothermal reservoir.

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Fan, Pang, Liao, Tian, Hao, Huang, and Li. "Hydrogeochemical Characteristics and Genesis of Geothermal Water from the Ganzi Geothermal Field, Eastern Tibetan Plateau." Water 11, no. 8 (August 7, 2019): 1631. http://dx.doi.org/10.3390/w11081631.

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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.

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Chang, Xing-Wang, Mo Xu, Liang-Wen Jiang, Xiao Li, and Yun-Hui Zhang. "Hydrogeochemical Characteristics and Formation of Low-Temperature Geothermal Waters in Mangbang-Longling Area of Western Yunnan, China." Journal of Chemistry 2021 (July 28, 2021): 1–13. http://dx.doi.org/10.1155/2021/5527354.

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Numerous low-temperature geothermal waters are distributed extensively in Mangbang-Longling of western Yunnan in China, whose formation mechanism has not been completely investigated yet. This study focused on the hydrogeochemical evolution, reservoir temperature, and recharge origin of geothermal waters using hydrogeochemical and deuterium-oxygen (D-O) isotopic studies. The low-temperature geothermal waters were characterized by HCO3-Na type, while shallow cold spring was of the hydrochemical type of HCO3-Ca. The hydrogeochemical characteristics of low-temperature geothermal waters were mainly determined by the dissolution of silicate minerals based on the geological condition and correlations of major and minor ions. The reservoir temperatures of low-temperature geothermal waters ranged from 111°C to 126°C estimated by silica geothermometry and the silicon-enthalpy graphic method. Low-temperature geothermal waters circulated at the largest depth of 1794–2077 m where deep high-temperature geothermal waters were involved. The data points of δD and δ18O of the hot spring water samples in the study area show a linear right-up trend, indicating the δ18O reaction between the water and rock and a possible mixture of magmatic water from below. The low-temperature thermal waters were recharged by meteoric water at the elevation of 2362–3653 m calculated by δD values. Upwelling by heating energy, low-temperature geothermal waters were exposed as geothermal springs in the fault and fracture intersection and mixed by up to 72% shallow cold waters at surface. Based on acquired data, a conceptual model of the low-temperature geothermal waters in the Mangbang-Longling area was proposed for future exploitation.

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Zhang, Wei, Guiling Wang, Linxiao Xing, Tingxin Li, and Jiayi Zhao. "Geochemical response of deep geothermal processes in the Litang region, Western Sichuan." Energy Exploration & Exploitation 37, no. 2 (November 28, 2018): 626–45. http://dx.doi.org/10.1177/0144598718812550.

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The geochemical characteristics of geothermically heated water can reveal deep geothermal processes, leading to a better understanding of geothermal system genesis and providing guidance for improved development and utilization of such resources. Hydrochemical and hydrogen oxygen isotope analysis of two geothermal field (district) hot springs based on regional geothermal conditions revealed that the thermal water in the Litang region is primarily of the HCO3Na type. The positive correlations found between F−, Li2+, As+, and Cl− indicated a common origin, and the relatively high Na+ and metaboric acid concentrations suggested a relatively long groundwater recharge time and a slow flow rate. The values of δD and δ18O were well distributed along the local meteoric line, indicating a groundwater recharge essentially driven by precipitation. The thermal reservoir temperature (152°C–195°C) and thermal cycle depth (3156–4070 m) were calculated, and the cold water mixing ratio (60%–68%) was obtained using the silica-enthalpy model. Finally, hydrogeochemical pathway simulation was used to analyze the evolution of geothermal water in the region. The results were further supported by the high metasilicate content in the region. Of the geothermal fields in the region, it was found that the Kahui is primarily affected by albite, calcite precipitation, and silicate, while the Gezha field is primarily affected by calcite dissolution, dolomite precipitation, and silicate.

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Ghori, K. Ameed. "Petroleum data: leading the search for geothermal resources in Western Australia." APPEA Journal 49, no. 1 (2009): 365. http://dx.doi.org/10.1071/aj08022.

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In Western Australian basins, subsurface drill-hole data, primarily from petroleum exploration, allows the identification of regions of high temperature at depth that may be potential geothermal resources. The extent and economic viability of such resources remain poorly known and require further study. Observed temperatures at depths up to 4.5 km reach 150°C in parts of the Canning, Carnarvon and Perth basins, indicating low-enthalpy resources related to regional heat flow. The greatest potential for hydrothermal resources is in the Perth Basin where subsurface temperatures of 65–85°C are reached at 2–3.5 km depth. Heat-flow modelling of 170 Perth Basin wells shows a range of 30–140 mW/m2, with the highest surface heat-flow values in the northern part of the basin. The median value of 76.5 mW/m2 for this basin exceeds the average reported for the Australian continent—64.5 mW/m2. Potential hot rocks resources are present in parts of the Canning, Carnarvon and Perth basins where the depth to 200°C is less than 5 km. Knowledge of high subhorizontal stress conditions that can enhance geothermal water flow from engineered reservoirs are based on data mostly from petroleum wells in the Perth Basin. A systematic quantitative assessment of geological, hydrogeological, geophysical, stress orientation and geochemical conditions is required to further delineate and prove these resources. Progressive compilation, validation and interpretation of subsurface data from more than 800 wells is underway, and includes temperature logs of 47 shallow water bores and 30 new thermal conductivity measurements of Perth Basin wells. Data compilation from 580 wells in the Canning, Carnarvon and Perth basins is complete. To date the greatest number of wells indicating high geothermal gradients and temperatures are in the Carnarvon Basin.

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Μπιρμπίλη, Μ., Κ. Χρηστάνης, Ν. Λαμπράκης, and Κ. Καρύτσας. "STUDY ON THE EXPLOITATION POSSIBILITY OF THE THERMA-NIGRITA GEOTHERMAL FIELD (PREFECTURE OF SERRES)." Bulletin of the Geological Society of Greece 36, no. 3 (January 1, 2004): 1182. http://dx.doi.org/10.12681/bgsg.16461.

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The aim of this study is to evaluate the potential of Therma Nigrita low-enthalpy geothermal field and to examine the possibility of exploitation. Six geothermal fluid samples and two cold-water samples were obtained from eight boreholes situated in the Therma field of Nigrita. Field measurements, as well as laboratory determinations using classic and modern methods of analyses were carried out. The temperature of the geothermal fluids ranges from 38,5 up to 62,5°C; the discharge rates of the boreholes range from 40 up to 70 m3/h. These data lead to the conclusion that the field is exploitable. Due to high As and Li contents and in order to avoid environmental impacts, it is essential to reinject the waste geothermal fluids into the geothermal reservoir. For the exploitation of the geothermal field, the applications of district heating and cooling of a part of Nigrita Municipality using heat pumps, in combination with greenhouse applications, are proposed. In order to save energy and reduce the capital cost, the above applications have to be placed in cascade. The energy production cost, including also the capital amortisation cost, of the above application amounts to 0.0226 €/kWh. The proposed geothermal applications have a significant economic advantage over the use of fossil fuels. Additionally, there is an important environmental benefit from avoiding the emission of severe quantities of CO2 (>8,000 tons annually), which would be emitted in case of oil use.

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Vandenberghe, Noël, Michiel Dusar, Paul Boonen, LIE Sun Fan, Rudy Voets, and Jos Bouckaert. "The Merksplas-Beerse geothermal well (17W265) and the Dinantian reservoir." Geologica Belgica 3, no. 3-4 (October 1, 2001): 349–67. http://dx.doi.org/10.20341/gb.2014.037.

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The Merksplas-Beerse well (North Belgium) is a low-enthalpy geothermal production well targeting the Dinantian karstic limestones to a total depth of 1761 m. The presence of methane gas in these limestones generated a particular interest in this well. This paper describes the geological profile of this well and the Dinantian reservoir. The Namurian-Visean boundary at 1630 m is determined by the base of the dipmeter draping pattern in the radioactive Chokier shales (base of the Namurian) on top of the karstified Dinantian limestone. The stratigraphic composition of the transitional interval from Dinantian to Silesian correlates closely to the nearby Turnhout well. The two fractured intervals at 1630-1656 and 1739-1747 m respectively were identified in the Dinantian limestones. They are associated with siliciclastic sections in between pure limestones. The reservoir water is a sodium chloride brine of about 74 °C and at a pressure below the hydrostatic. The water is slightly radioactive because of the contact with the Chokier hot shales. A carbon dioxide gas with methane and nitrogen admixture is dissolved in the water. The gas liquid ratio at standard conditions is about one and the bubble point is around 200-400 psi at reservoir temperature. A long duration pumping test shows a high fracture permeability and a productivity index of 5.4 m3/h/bar with a productivity to injectivity ratio of 1.45.

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Maza, S. N., G. Collo, D. Morata, C. Lizana, E. Camus, M. Taussi, A. Renzulli, et al. "Clay mineral associations in the clay cap from the Cerro Pabellón blind geothermal system, Andean Cordillera, Northern Chile." Clay Minerals 53, no. 2 (June 2018): 117–41. http://dx.doi.org/10.1180/clm.2018.9.

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ABSTRACTThe occurrence of smectite-illite and smectite-chlorite minerals series was studied along a thick clay cap (~300 m) drilled in the Cerro Pabellón geothermal field (northern Andes, Chile). X-ray diffraction (XRD) and scanning electronic microscopy (SEM) were used to characterize the alteration mineralogy and clay mineral assemblages and their changes with depth. Cerro Pabellón is a high-enthalpy blind geothermal system, with a reservoir zone from ~500 m to 2000 m depth, with temperatures of 200–250°C. Three main hydrothermal alteration zones were identified: (1) argillic; (2) sub-propylitic, and (3) propylitic, with variable amounts of smectite, illite-smectite, chlorite-smectite, mixed-layer chlorite-corrensite, illite and chlorite appearing in the groundmass and filling amygdales and veinlets. Chemical and XRD data of smectites, I-S and illites show, with some exceptions, a progressive illitization with depth. The evolution of I-S with depth, shows a sigmoidal variation in the percentage of illite layers, with the conversion of smectite to R1 I-S at ~180–185°C. These temperatures are greater than those reported for other similar geothermal fields and might indicate, at least in part, the efficiency of the clay cap in terms of restricting the circulation of hydrothermal fluids in low-permeability rocks. Our results highlight the importance of a better understanding of clay-mineral evolution in active geothermal systems, not only as a direct (or indirect) way to control temperature evolution, but also as a control on permeability/porosity efficiency of the clay cap.

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Rybach, Ladislaus. "Geothermal Sustainability or Heat Mining?" International Journal of Terrestrial Heat Flow and Applications 4, no. 1 (March 22, 2021): 15–25. http://dx.doi.org/10.31214/ijthfa.v4i1.61.

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Heat mining” is, in fact a complete deceptive misnomer. When a mineral deposit (e.g. copper) is mined and the ore has been taken out, it will be gone forever. Not so with geothermal resources: The heat and the fluid are coming back! Namely, the heat and fluid extraction create heat sinks and hydraulic minima; around these, strong temperature and pressure gradients develop. Along the gradients, natural inflow of heat and fluid arises to replenish the deficits. The inflow from the surroundings can be strong: around borehole heat exchangers, heat flow densities of several W/m2 result, whereas terrestrial heat flow amounts only to about 50 – 100 mW/m2. The regeneration of geothermal resources after production, in other words, extraction of fluid and/or heat) is a process that runs over different timescales, depending on the kind and size of the utilization system, the production rate, and the resource characteristics. The resource renewal depends directly on the heat/fluid backflow rate. Heat, respectively fluid production from geothermal resources can be accomplished with different withdrawal rates. Although forced production is more attractive financially (with quick payback), it can nevertheless degrade the resource permanently. The longevity of the resource (and thus the sustainability of production) can be ensured by moderate production rates. The sustainable geothermal production level depends on the utilization technology as well as on the local geologic conditions. The stipulation of the sustainable production level requires specific clarifications, especially by numerical modelling, based on long-term production strategies. In general, resource regeneration proceeds asymptotically: strong at the beginning and slowing down subsequently, reaching the original conditions only after infinite time. However, regeneration to 95 % can be achieved much earlier, e.g. within the lifetime of the extraction/production system. In other words, geothermal resources may under certain circumstances may be considered as having potential regrowth, like biomass. Concerning the requirements for such sustainable production, it is convenient to consider four resource types and utilization schemes. These may be treated by numerical model simulations that consider heat extraction by geothermal heat pumps, hydrothermal aquifer, used by a doublet system for space heating, high enthalpy two-phase reservoir, tapped to generate electricity, and enhanced Geothermal Systems (EGS).

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Varga, Andrea, Gábor Bozsó, István Garaguly, Béla Raucsik, Attila Bencsik, and Balázs Kóbor. "Cements, Waters, and Scales: An Integrated Study of the Szeged Geothermal Systems (SE Hungary) to Characterize Natural Environmental Conditions of the Thermal Aquifer." Geofluids 2019 (April 24, 2019): 1–21. http://dx.doi.org/10.1155/2019/4863814.

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The study area, Pannonian Basin (Central Europe), is characterized by high heat flow and presence of low-enthalpy geothermal waters. In the Szeged Geothermal Systems (Hungary), having Miocene to Pliocene sandstone aquifers with dominantly Na–HCO3-type thermal water, unwanted carbonate scaling was observed. An integrated approach consisting of host rock and scale mineralogical and petrographic analyses as well as water chemistry led to a better understanding of the characteristic natural (geogenic) environmental conditions of the geothermal aquifers and to highlight their technical importance. Analyses of the reservoir sandstones showed that they are mineralogically immature mixed carbonate-siliciclastic rocks with significant macroporosity. Detrital carbonate grains such as dolomite and limestone fragments appear as important framework components (up to ~20–25%). During water–rock interactions, they could serve as a potential source of the calcium and bicarbonate ions, contributing to the elevated scaling potential. Therefore, this sandstone aquifer cannot be considered as a conventional siliciclastic reservoir. In mudrocks, a significant amount of organic matter also occurs, triggering CO2producing reactions. Correspondingly, framboidal pyrite and ferroan calcite are the main cement minerals in all of the studied sandstone samples which can suggest that calcite saturation state of the thermal fluid is close to equilibrium in oxygen-depleted pore water. Analysis of the dominant carbonate crystals in the scale can suggest that growth of the feather dendrites of low-Mg calcite was probably driven by rapid CO2degassing of CO2-rich thermal water under far-from-equilibrium conditions. Based on hydrogeochemical data and related indices for scaling and corrosion ability, the produced bicarbonate-rich (up to 3180 mg/l) thermal water has a significant potential for carbonate scaling which supports the aforementioned statement. Taking into consideration our present knowledge of geological setting of the studied geothermal systems, temporal changes in chemical composition and temperature of the thermal water during the heating period can indicate upwelling fluids from a deep aquifer. Regarding the pre-Neogene basement, hydrologic contact with a Triassic carbonate aquifer might be reflected in the observed chemical features such as decreased total dissolved solids and increased bicarbonate content with high scale-forming ability. The proposed upflow of basin-derived water could be channeled by Neogene to Quaternary fault zones, including compaction effects creating fault systems above the elevated basement high. The results may help to understand the cause of the high carbonate scale precipitation rates in geothermal systems tapping sandstone aquifers.

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Reich, Martin, Nelson Román, Fernando Barra, and Diego Morata. "Silver-Rich Chalcopyrite from the Active Cerro Pabellón Geothermal System, Northern Chile." Minerals 10, no. 2 (January 28, 2020): 113. http://dx.doi.org/10.3390/min10020113.

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Active subaerial geothermal systems are regarded as modern analogues of low- to intermediate-sulfidation epithermal Au–Ag deposits, where minor amounts of Cu are mostly present as chalcopyrite. Although trace element data concerning sulfides are scarce in active geothermal systems at convergent settings, studies in several other environments have demonstrated that chalcopyrite is a relevant host of Ag and other trace elements. Here, we focus on the active Cerro Pabellón geothermal system in the Altiplano of northern Chile, where chalcopyrite-bearing samples were retrieved from a 561 m drill core that crosscuts the high-enthalpy geothermal reservoir at depth. A combination of EMPA and LA-ICP-MS data shows that chalcopyrite from Cerro Pabellón is silver-rich (Ag > 1000 ppm) and hosts a wide range of trace elements, most notably Se, Te, Zn, Sb, As, and Ni, which can reach 100 s of ppm. Other elements detected include Co, Pb, Cr, Ga, Ge, Sn, Cd, and Hg but are often present in low concentrations (<100 ppm), whereas Au, Bi, Tl, and In are generally below 1 ppm. Chalcopyrite shows a distinct geochemical signature with depth, with significantly higher Ag concentrations in the shallow sample (494 m) and increasing Cd and In contents towards the bottom of the studied drill core (549 m). These differences in the trace element contents of chalcopyrite are interpreted as related to temperature gradients during the waning stages of boiling at Cerro Pabellón, although further studies are still needed to assess the precise partitioning controls. Our data provide evidence that chalcopyrite may play a relevant role as a scavenger of certain metals and a monitor of fluid changes in hydrothermal systems.

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Cocozza, A., and A. Ficarella. "Electrical Resistivity Measures in Cohesive Soils for the Simulation of an Integrated Energy System Between CCS and Low-Enthalpy Geothermal." International Journal of Measurement Technologies and Instrumentation Engineering 3, no. 1 (January 2013): 48–68. http://dx.doi.org/10.4018/ijmtie.2013010105.

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This work has focused on the possibility of being able to consider the behavior of the caprock, such as a layer of cohesive soil that absorbs and transfers the displacement due to the expansion of the aquifer subject to the action of the flow of CO2 at high pressure, but lower than the overburden of the geological formations overlying the caprock. Assuming a caprock saturated unconfined laterally, which drains over time overpressure neutral interstitial fluid present in the matrix of cohesive soils, it has been calculated at the rate derived from the elastic yielding of consolidation theory and compared this value with the one obtained by applying a coefficient of consolidation built on the theory of the “double layer”. This theory also known as the Gouy-Chapman (1910) was applied to the prediction of the behavior of cohesive soils where it conducted a micro-mechanistic approach. From the design point of view, the second part of the study simulate the possibility of combining in a single integrated system, the injection of CO2 in deep saline aquifers to generate a range of pressures that facilitates the upgrade of geothermal fluids from geological formations that constitute the caprock or any porous aquifers overlaid with the aquifer reservoir. The uptake of these fluids promotes dissipate excess pressure and at the same time the settlement of primary consolidation of the formations overlying the aquifer subjected to the vertical elastic displacement. Preserves itself, in this way, the balance of the system and shows how the CCS can have a double purpose: on the one hand reduce the emission of CO2 into the atmosphere, and the other end to provide a energy contribution with the exploitation of a source of renewable energy.

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Bragin, Ivan V., Elena V. Zippa, George A. Chelnokov, and Natalia A. Kharitonova. "Estimation of the Deep Geothermal Reservoir Temperature of the Thermal Waters of the Active Continental Margin (Okhotsk Sea Coast, Far East of Asia)." Water 13, no. 9 (April 21, 2021): 1140. http://dx.doi.org/10.3390/w13091140.

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Low-enthalpy thermal waters (30–70 °C) with nitrogen as a dominant associated gas are spread within the active continental margin of the Russian Far East (east and north of the Okhotsk Sea Coast) and traditionally are of great importance for recreation and balneology facilities. The thermal waters are chemically classified into three groups: (i) Na–HCO3(SO4) type, with low TDS (0.2 g/L) and lowest temperature (<50 °C) and high pH (9.1–9.3), (ii) Na–SO4 type with TDS (~1 g/L), highest temperature (70 °C) and weak alkaline pH (8.7) and (iii) Ca–Na–Cl type with high TDS (15 g/L), moderate T (59 °C) and neutral pH (7.5). The δ18O and δD values suggest that the thermal waters originate from meteoric water, and they are not isotopically fractionated. Silica and cation geothermometers and thermodynamic equilibrium calculations using the GeoT and PHREEQC programs indicate a reservoir temperature for the Na–HCO3(SO4) type thermal waters of 103–121 °C and for Na–SO4 and Ca–Na–Cl types of 136 and 153 °C, respectively. The evaluation of the mixing degree of the thermal water with cold groundwater shows that the equilibration temperature ranges between 148 and 153 °C. Estimated circulation depths for thermal manifestations range from 2.7 to 4.3 km and may be as great as 6 km.

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Wu, Xingru, Gary A. Pope, G. Michael Shook, and Sanjay Srinivasan. "Prediction of enthalpy production from fractured geothermal reservoirs using partitioning tracers." International Journal of Heat and Mass Transfer 51, no. 5-6 (March 2008): 1453–66. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2007.06.023.

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Legarth, Bjoern, Torsten Tischner, and Ernst Huenges. "Stimulation experiments in sedimentary, low-enthalpy reservoirs for geothermal power generation, Germany." Geothermics 32, no. 4-6 (August 2003): 487–95. http://dx.doi.org/10.1016/j.geothermics.2003.07.007.

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Poulsen, S. E., N. Balling, and S. B. Nielsen. "A parametric study of the thermal recharge of low enthalpy geothermal reservoirs." Geothermics 53 (January 2015): 464–78. http://dx.doi.org/10.1016/j.geothermics.2014.08.003.

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Kaczmarczyk, Michał, Barbara Tomaszewska, and Leszek Pająk. "Geological and Thermodynamic Analysis of Low Enthalpy Geothermal Resources to Electricity Generation Using ORC and Kalina Cycle Technology." Energies 13, no. 6 (March 13, 2020): 1335. http://dx.doi.org/10.3390/en13061335.

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The article presents an assessment of the potential for using low enthalpy geothermal resources for electricity generation on the basis of the Małopolskie Voivodeship (southern Poland). Identification the locations providing the best prospects with the highest efficiency and possible gross power output. Thermodynamic calculations of power plants were based on data from several geothermal wells: the Bańska PGP-1, Bańska IG-1, Bańska PGP-3 and Chochołów PIG-1 which are working wells located in one of the best geothermal reservoirs in Poland. As the temperature of geothermal waters from the wells does not exceed 86 °C, considerations include the use of binary technologies—the Organic Rankine Cycle (ORC) and Kalina Cycle. The potential gross capacity calculated for existing geothermal wells will not exceed 900 kW for ORC and 1.6 MW for Kalina Cycle. In the case of gross electricity, the total production will not exceed 3.3 GWh/year using the ORC, and will not exceed 6.3 GWh/year for the Kalina Cycle.

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Feng, Yin, Mayank Tyagi, and Christopher D. White. "A downhole heat exchanger for horizontal wells in low-enthalpy geopressured geothermal brine reservoirs." Geothermics 53 (January 2015): 368–78. http://dx.doi.org/10.1016/j.geothermics.2014.07.007.

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Buzăianu, Aurelian, Ioana Csáki, Petra Moţoiu, Gabriela Popescu, Ingolfur Thorbjornsson, Kolbrun R. Ragnarsodottir, Sæmundur Guðlaugsson, and Daniel Goubmunson. "Recent Advances of the Basic Concepts in Geothermal Turbines of Low and High Enthalpy." Advanced Materials Research 1114 (July 2015): 233–38. http://dx.doi.org/10.4028/www.scientific.net/amr.1114.233.

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A few numbers of countries in the world are involved in geothermal exploration and geothermal development projects. In order to provide a stable power supply without increasing carbon dioxide on global environment problem, a basic condition need to be fulfilled. This condition is high reliability and high maintainability for the geothermal energetic pumps and turbines. Effective efficiency improvement and geothermal turbines system upgrading are very important and also fundamental economical factor. This means that CO2 emissions into the atmosphere are minimal and a higher reliance on geothermal power generation would work on preventing global warming.The solution to climate changes threat is based now, mainly, on renewable and ecological sources of energy. Geothermal energy has the potential to play a significant role in moving the Europe and other regions of the world toward a cleaner and more sustainable energy system. In order to increase the reliability of geothermal steam turbines, assessing the materials life under geothermal environment condition will be an important step. The corrosion process in the geothermal turbine and pumps depends on temperature, pressure, chemistry, mechanical and vaporous carryover of impurities and water treatment (distribution between the vapors, the surface film and rotor blades material, heat transfer properties etc).The aim of this paper is to present a new coating method for geothermal turbines and pumps components using multi composite technology in order to obtain a protective layer to reduce corrosion damages. The results were very promising and the technique used, plasma jet spraying is a very good method to be used on the geothermal turbines and pumps components.

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Crooijmans, R. A., C. J. L. Willems, H. M. Nick, and D. F. Bruhn. "The influence of facies heterogeneity on the doublet performance in low-enthalpy geothermal sedimentary reservoirs." Geothermics 64 (November 2016): 209–19. http://dx.doi.org/10.1016/j.geothermics.2016.06.004.

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Yuan, Wanju, Zhuoheng Chen, Stephen E. Grasby, and Edward Little. "Closed-loop geothermal energy recovery from deep high enthalpy systems." Renewable Energy 177 (November 2021): 976–91. http://dx.doi.org/10.1016/j.renene.2021.06.028.

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Martín-Gamboa, Mario, Diego Iribarren, and Javier Dufour. "On the environmental suitability of high- and low-enthalpy geothermal systems." Geothermics 53 (January 2015): 27–37. http://dx.doi.org/10.1016/j.geothermics.2014.03.012.

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Aravena, Diego, Mauricio Muñoz, Diego Morata, Alfredo Lahsen, Miguel Ángel Parada, and Patrick Dobson. "Assessment of high enthalpy geothermal resources and promising areas of Chile." Geothermics 59 (January 2016): 1–13. http://dx.doi.org/10.1016/j.geothermics.2015.09.001.

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Scott, Samuel, Thomas Driesner, and Philipp Weis. "The thermal structure and temporal evolution of high-enthalpy geothermal systems." Geothermics 62 (July 2016): 33–47. http://dx.doi.org/10.1016/j.geothermics.2016.02.004.

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Donovan, P. R. "The status of high enthalpy geothermal exploration in the developing countries." Geothermics 14, no. 2-3 (January 1985): 487–94. http://dx.doi.org/10.1016/0375-6505(85)90086-0.

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Menéndez, Javier, and Jorge Loredo. "Low-enthalpy Geothermal Energy Potential of Mine Water from Closured Underground Coal Mines in Northern Spain." E3S Web of Conferences 103 (2019): 02007. http://dx.doi.org/10.1051/e3sconf/201910302007.

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The contribution of renewable energies to the world's total energy demand has increased particularly during the last decades, and they will continue gaining market share. The European energy and climate policies have as one of their targets 20% of final energy from renewable origin by 2020. Underground coal mines closured and flooded constitute large underground reservoirs that can be economically managed to supply geothermal energy (heating and cooling) by means of heat pumps. This paper analyzes the geothermal potential of the water stored inside the coal mines of the Asturian Central Coal Basin (ACCB) and the reduction of CO2 emissions compared to the use of fossil fuels. The results of the study that has been carried out show a capacity of 50 MWt. The potential for generation thermal energy is 112,000 MWh/year with an electric consumption of 14,000 MWh/year. The Coefficient Of Performance (COP) medium is 8 kWht/kWhe. The reduction of CO2 emissions compared to other fuel sources can reach 80%.

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Kiryukhin, Alexey, Pavel Voronin, Nikita Zhuravlev, Andrey Polyakov, Tatiana Rychkova, Vasily Lavrushin, Elena Kartasheva, Natalia Asaulova, Larisa Vorozheikina, and Ivan Chernev. "Isotopes & Geochemistry: Tools For Geothermal Reservoir Characterization (Kamchatka Examples)." E3S Web of Conferences 98 (2019): 08013. http://dx.doi.org/10.1051/e3sconf/20199808013.

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The thermal, hydrogeological, and chemical processes affecting Kamchatka geothermal reservoirs were studied by using isotope and geochemistry data: (1) The Geysers Valley hydrothermal reservoirs; (2) The Paratunsky low temperature reservoirs; (3) The North-Koryaksky hydrothermal system; (4) The Mutnovsky high temperature geothermal reservoir; (5) The Pauzhetsky geothermal reservoir. In most cases water isotope in combination with Cl- transient data are found to be useful tool to estimate reservoirs natural and disturbed by exploitation recharge conditions, isotopes of carbon-13 (in CO2) data are pointed either active magmatic recharge took place, while SiO2 and Na-K geothermometers shows opposite time transient trends (Paratunsky, Geysers Valley) suggest that it is necessary to use more complicated geochemical systems of water/mineral equilibria.

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Scott, Samuel W. "Decompression boiling and natural steam cap formation in high-enthalpy geothermal systems." Journal of Volcanology and Geothermal Research 395 (April 2020): 106765. http://dx.doi.org/10.1016/j.jvolgeores.2019.106765.

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Kivanc Ates, H., and U. Serpen. "Power plant selection for medium to high enthalpy geothermal resources of Turkey." Energy 102 (May 2016): 287–301. http://dx.doi.org/10.1016/j.energy.2016.02.069.

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Simpson, Mark P., and Greg Bignall. "Undeveloped high-enthalpy geothermal fields of the Taupo Volcanic Zone, New Zealand." Geothermics 59 (January 2016): 325–46. http://dx.doi.org/10.1016/j.geothermics.2015.08.006.

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Zhang, Liang, Hancheng Ji, Liang Chen, Jinxia Liu, and Haiquan Li. "Characteristics of geothermal reservoirs in the Wumishan Formation and groundwater of the Middle-Upper Proterozoic and the geothermal status in the Beijing–Tianjin–Hebei region: Implications for geothermal resources exploration." Energy Exploration & Exploitation 37, no. 2 (March 2019): 811–33. http://dx.doi.org/10.1177/0144598718798100.

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Exploration of the geothermal resources in the Beijing–Tianjin–Hebei region has been kept for tens of years, and the recent success of geothermal exploration in the Xiongxian County provides a new model for the utilization of geothermal resources in this area. This research integrates the formation of temperature obtained from hydrocarbon drilling, experiments of reservoirs’ micro-characteristics and physical property, and employs the previous works on the regional geological settings to investigate the geothermal reservoirs and geothermal status. The microphotography indicates that the reservoir space is dominated by supergene karst in the Wumishan Formation which is mainly controlled by the topography when the interval emerged. The groundwater in the Pre-Paleogene has the similar composition of the hydrogen and oxygen isotope with the atmospheric precipitation, and the salinity of the groundwater has an increasing trend from the Taihang Mountain and the Yanshan Mountain to the depocenters, which indicates the groundwater originates from the atmospheric precipitation of the Taihang Mountain and the Yanshan Mountain and transports to the depocenters. The thermal conductivity of the lower carbonate rocks is much higher than the upper clastic intervals. This difference makes the upper clastic intervals of the Paleogene and the Neogene good seals for geothermal reservoirs and leads to the regional anomaly of the terrestrial heat flow: the intrabasin highs have a thicker thickness of the Pre-Paleogene carbonate deposition with high thermal conductivity, which results in high efficient thermal transmission and high terrestrial heat flow. Consequently, this research suggests that the intrabasin highs and slopes are the favourable areas for geothermal exploration with reservoirs of good quality, high terrestrial heat flow and efficient groundwater supply, and several areas were selected to be the potential targets for the Wumishan Formation and the Pre-Paleogene.

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Bodvarsson, Gudmundur S., Karsten Pruess, and Michael J. O'Sullivan. "Injection and Energy Recovery in Fractured Geothermal Reservoirs." Society of Petroleum Engineers Journal 25, no. 02 (April 1, 1985): 303–12. http://dx.doi.org/10.2118/11689-pa.

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Abstract Numerical studies of the effects of injection on the behavior of production wells completed in fractured two-phase geothermal reservoirs are presented. In these studies the multiple-interacting-continua (MINC) method is employed for the modeling of idealized fractured reservoirs. Simulations are carried out for a five-spot well pattern with various well spacings, fracture spacings, and pattern with various well spacings, fracture spacings, and injection fractions. The production rates from the wells are calculated using a deliverability model. The results of the studies show that injection into two-phase fractured reservoirs increases flow rates and decreases enthalpies of producing wells. These two effects offset each other so that injection tends to have small effects on the usable energy output of production wells in the short term. However, if a sufficiently large fraction of the produced fluids is injected, the fracture system may become liquid-filled and an increased steam rate is obtained. Our studies show that injection greatly increases the long-term energy output from wells because it helps extract heat from the reservoir rocks. If a high fraction of the produced fluids is injected, the ultimate energy recovery will increase many-fold. Introduction At present, reinjection of geothermal brines is employed or being considered at most high-temperature geothermal fields under development. At many geothermal fields, primarily those in the U.S. or Japan, reinjection is a primarily those in the U.S. or Japan, reinjection is a necessity because environmental considerations do not permit surface disposal of the brines (unacceptable permit surface disposal of the brines (unacceptable concentrations of toxic minerals). At other fields (e.g., The Geysers, CA) reinjection is used for reservoir management to help maintain reservoir pressures and to enhance energy recovery from the reservoir rocks. The effectiveness of injection in maintaining reservoir pressures has been illustrated at the Ahuachapan geothermal field in El Salvador. During the last decade various investigators have studied the effects of injection on pressures and overall energy recovery from geothermal fields. Theoretical studies have been carried out by Kasameyer and Schroeder, Lippmann et al., O'Sullivan wad Pruess, Schroeder et al., and Pruess, among others. Site-specific studies were reported by Morris and Campbell on East Mesa, CA; Schroeder et al. and Giovannoni et al. on Larderello, Italy; Bodvarsson et al. on Baca, NM; Tsang et al. on Cerro Prieto, Mexico; and Jonsson and Pruess et al. on Krafla, Iceland. These studies have given valuable insight into physical processes and reservoir response during injection. However, there is limited understanding of injection effects in fractured reservoirs, especially high-temperature, two-phase systems. Fundamental studies and quantitative results for the design of injection programs in such systems are greedy needed. The objectives of the present work are to investigate the effects of injection on the behavior of fractured two-phase reservoirs. Several questions will be addressed.How will injection affect flow rates and enthalpies of the production wans?Can injection increase the short-term usable energy output of well?What are the long-term effects of injection?How is the efficiency of injection dependent on factors such as well spacing and fracture spacing? Reliable answers to these questions should be valuable for field operators in the design of injection systems for two-phase fractured reservoirs. Approach In the present work we consider wells arranged in a five-spot pattern (Fig. 1). Because of symmetry we only need to model one-eighth of a basic element as shown in Fig. 1; however, our results always are presented for the full five spot. The "primary" (porous medium) mesh shown in Fig. 1 consists of 38 elements; some of the smaller ones close to the wells are not shown. The mesh has a single layer, so that gravity effects are neglected. The fractured reservoir calculations are carried out by the MINC method, which is a generalization of the double-porosity concept introduced by Barenblatt et al. and Warren and Root. The basic reservoir model consists of rectangular matrix blocks bounded by three sets of orthogonal infinite fractures of equal aperture b and spacing D (Fig. 2a. M the mathematical formulation the fractures with high transport and low storage capacity are combined into one continuum and the low-permeability, high storativity matrix blocks into another. The MINC method treats transient flow of fluid (steam and/or water) and heat between the two continua by means of numerical methods. Resolution of the pressure and temperature gradients at the matrix/fracture interface is achieved by partitioning of the matrix blocks into a series of interacting partitioning of the matrix blocks into a series of interacting continua. SPEJ P. 303

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41

Takács, Ján. "Possibility of Geothermal Water’s Using in Geothermal Energy Systems." Periodica Polytechnica Mechanical Engineering 61, no. 4 (September 29, 2017): 272. http://dx.doi.org/10.3311/ppme.10546.

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Slovakia belongs to countries rich in geothermal energy resources with high productiveness. The use of geothermal energy (GE) is diverse, e.g. as source for centralized heating networks. The use of this alternative Energy Sources requires optimized exploitation of the energy potential. When using GE it is vital to design systems with cascade utilization of GE to increase the efficiency and have minimal impact on environment. When using GE we have not only take in account physical and chemical properties of geothermal water (GTW) reservoirs, but standards and regulations, as well as limitations given by the delivery points, which apply no matter what type of energy source we use – conventional or alternative.

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Colmenar-Santos, Antonio, Elisabet Palomo-Torrejón, Enrique Rosales-Asensio, and David Borge-Diez. "Measures to Remove Geothermal Energy Barriers in the European Union." Energies 11, no. 11 (November 18, 2018): 3202. http://dx.doi.org/10.3390/en11113202.

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This article examines the main market barriers that hamper the introduction of geothermal energy at local, national, and European levels as well as the necessary steps that need to be taken to eradicate them, thus contributing to the general use of this renewable source of energy. The novelty of this study lies in the detailed description of four different scenarios: the European Union (EU), Spain, the Canary Islands, and the agricultural sector for the three types of geothermal energies and their uses: Low-enthalpy or thermal uses, high-enthalpy or electrical uses and renewable energy mix. The results are expected to differ in terms of level of introduction, barriers, and measures to be taken. We have selected Spain within the European context due to its meagre 0.1% geothermal market share in primary demand for renewable energy, and the Canary Islands in particular, given its insular nature. We have likewise picked the agricultural sector due to its underdevelopment as far as renewable energies are concerned, including geothermal energy.

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Kana, Janvier Domra, Noël Djongyang, Danwé Raïdandi, Philippe Njandjock Nouck, Robert Nouayou, Tabod Charles Tabod, and Oumarou Sanda. "Geophysical investigation of low enthalpy geothermal potential and ground water reservoirs in the Sudano-Sahelian region of Cameroon." Journal of African Earth Sciences 110 (October 2015): 81–91. http://dx.doi.org/10.1016/j.jafrearsci.2015.06.007.

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Guo, Zhu, Qiu, Tang, Cui, Zhang, and Zhao. "Present Geothermal Characteristics and Influencing Factors in the Xiong’an New Area, North China." Energies 12, no. 20 (October 14, 2019): 3884. http://dx.doi.org/10.3390/en12203884.

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The present geothermal characteristics and influencing factors are analyzed to conduct geothermal resource exploration in the Xiong’an New Area. Thermal conductivity data for 100 rock samples are obtained from different wells and a sedimentary strata thermal conductivity column is proposed. From these data, heat flow distribution in the area is mapped using equilibrium temperature logs obtained for 32 wells. The heat flow in this area is found to be 53.3–106.5 mW·m−2 (average: 73 mW·m−2). The uplift heat value in Niutuozhen and Rongcheng uplift is 106.5 and 90 mW·m−2, respectively. The sag heat flow is relatively low and the Baxian sag’s heat flow value is 48.9–61.6 mW·m−2. Thermal conductivity differences among Cenozoic caprock, Proterozoic carbonate reservoirs, and basement rock mainly affects the geothermal distribution. The low and high thermal conductivities of the caprock and thermal reservoir as well as basement, respectively, cause heat flow redistribution in the surface during conduction. Groundwater rises to geothermal reservoirs through heat-controlling faults, causing convective heat transfer and increasing the geothermal reservoir temperature; therefore, high-temperature groundwater accumulates in the shallow uplift areas. The caprock’s thin uplift area exhibits a high geothermal background due to water convergence. Understanding the geothermal characteristics and influencing factors is necessary for understanding the distribution law and factors influencing geothermal resources and guiding geothermal exploration and development in the Xiong’an New Area.

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Pátzay, György, Franciska H. Kármán, and György Póta. "Preliminary investigations of scaling and corrosion in high enthalpy geothermal wells in Hungary." Geothermics 32, no. 4-6 (August 2003): 627–38. http://dx.doi.org/10.1016/s0375-6505(03)00068-3.

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Didana, Y. L., S. Thiel, and G. Heinson. "Three dimensional conductivity model of the Tendaho High Enthalpy Geothermal Field, NE Ethiopia." Journal of Volcanology and Geothermal Research 290 (January 2015): 53–62. http://dx.doi.org/10.1016/j.jvolgeores.2014.11.013.

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Akbar, S., N. Fathianpour, and R. Al Khoury. "A finite element model for high enthalpy two-phase flow in geothermal wellbores." Renewable Energy 94 (August 2016): 223–36. http://dx.doi.org/10.1016/j.renene.2016.03.034.

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Zhang, Yi, and Dong Ming Guo. "Thermal Environment Simulation of Buildings on the Ground in Low Enthalpy Geothermal Engineering." Advanced Materials Research 393-395 (November 2011): 476–80. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.476.

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By using a variety of energy-saving technologies, low-grade geothermal energy will be efficiently used for improving the indoor thermal environment with few high-grade electric energy in low enthalpy geothermal engineering. In order to be more targeted and precise, geothermal energy conservation engineering should be designed and controlled on the basis of characteristics and variation of indoor thermal environment. Taking the low enthalpy geothermal engineering in the Air Force Command Academy veteran cadre living area as an example, it generalizes the building and simulates the indoor thermal environment by DeST software. The results show that the thermal enironment of rooms which are on the different storeies and different orientations is different. it is be obvious regularity, the thermal enironment of rooms in the high storey and low storey is worse than the middle storey in winter, the thermal enironment of rooms in north is worse than in south, the thermal enironment of rooms in west is worse than in east, and the thermal enironment of rooms in the corner is worse than in the middle. All of these may be a guide to equipment selection, layout of pipe network and terminal equipment, and can provide a theoretical basis for energy conservation design and operations control.

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Zhang, Xiao Ling, Hong Zhan Liu, and Kang Chen. "Geothermal Geology Characteristic and Origin Analysis of Shilin Basin in Yunnan Province." Advanced Materials Research 779-780 (September 2013): 1449–52. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1449.

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based on geothermal anomalies and geothermal wells of Shilin basin, the structure of geothermal reservoirs, geothermal geological characteristics and hydrochemistry of thermal groundwater are examined. Geothermal reservoir of the geothermal field is Proterozoic Sinian dolomite and dolomitic limestone. Characteristic of geothermal water runoff and geothermal field are controlled by Jiuxiang fracture and Niutoushan ancient mainland. The drillings data shows that the temperature gradient is 1.5-4.8°C/100m. Deep circulation is the main origin of geothermal water. The chemical type of geothermal water is HCO3-Ca, and high silicic acid content. The geothermal water supply is limited from the hydrogeological conditions; we should control the development and utilization.

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Benn, Douglas I., Robert L. Jones, Adrian Luckman, Johannes J. Fürst, Ian Hewitt, and Christian Sommer. "Mass and enthalpy budget evolution during the surge of a polythermal glacier: a test of theory." Journal of Glaciology 65, no. 253 (August 29, 2019): 717–31. http://dx.doi.org/10.1017/jog.2019.63.

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Abstract:

AbstractAnalysis of a recent surge of Morsnevbreen, Svalbard, is used to test predictions of the enthalpy balance theory of surging. High-resolution time series of velocities, ice thickness and crevasse distribution allow key elements of the enthalpy (internal energy) budget to be quantified for different stages of the surge cycle. During quiescence (1936–1990), velocities were very low, and geothermal heat slowly built-up enthalpy at the bed. Measurable mass transfer and frictional heating began in 1990–2010, then positive frictional heating-velocity feedbacks caused gradual acceleration from 2010 to 2015. Rapid acceleration occurred in summer 2016, when extensive crevassing and positive air temperatures allowed significant surface to bed drainage. The surge front reached the terminus in October 2016, coincident with a drop in velocities. Ice plumes in the fjord are interpreted as discharge of large volumes of supercooled water from the bed. Surge termination was prolonged, however, indicating persistence of an inefficient drainage system. The observations closely match predictions of the theory, particularly build-up of enthalpy from geothermal and frictional heat, and surface meltwater, and the concomitant changes in ice-surface elevation and velocity. Additional characteristics of the surge reflect spatial processes not represented in the model, but can be explained with respect to enthalpy gradients.

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Journal articles on the topic 'High enthalpy geothermal reservoirs'

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