Geothermal Energy最新文献

{"title":"Efficiency and heat transport processes of low-temperature aquifer thermal energy storage systems: new insights from global sensitivity analyses","authors":"Luka Tas,&nbsp;Niels Hartog,&nbsp;Martin Bloemendal,&nbsp;David Simpson,&nbsp;Tanguy Robert,&nbsp;Robin Thibaut,&nbsp;Le Zhang,&nbsp;Thomas Hermans","doi":"10.1186/s40517-024-00326-1","DOIUrl":"10.1186/s40517-024-00326-1","url":null,"abstract":"<div><p>Aquifer thermal energy storage (ATES) has great potential to mitigate CO₂ emissions associated with the heating and cooling of buildings and offers wide applicability. Thick productive aquifer layers have been targeted first, as these are the most promising hydrogeological context for ATES. Regardless, there is currently an increasing trend to target more complex aquifers such as low-transmissivity and alluvial aquifers or fractured rock formations. There, the uncertainty of subsurface characteristics and, with that, the risk of poorly performing systems is considerably higher. Commonly applied strategies to decide upon the ATES feasibility and well design standards for optimization need to be adapted. To further promote the use of ATES in such less favorable aquifers an efficient and systematic methodology evaluating the optimal conditions, while not neglecting uncertainty, is crucial. In this context, the distance-based global sensitivity analysis (DGSA) method is proposed. The analysis focuses on one promising thick productive aquifer, first used to validate the methodology, as well as a complex shallow alluvial aquifer. Through this method, multiple random model realizations are generated by sampling each parameter from a predetermined range of uncertainty. The DGSA methodology validates that the hydraulic conductivity, the natural hydraulic gradient and the annual storage volume dominate the functioning of an ATES system in both hydrogeological settings. The method also advances the state of the art in both settings. It efficiently identifies most informative field data ahead of carrying out the field work itself. In the studied settings, Darcy flux measurements can provide a first estimate of the relative ATES efficiency. It further offers a substantiated basis to streamline models in the future. Insensitive parameters can be fixed to average values without compromising on prediction accuracy. It also demonstrates the insignificance of seasonal soil temperature fluctuations on storage in unconfined shallow aquifers and it clarifies the thermal energy exchange dynamics directly above the storage volume. Finally, it creates the opportunity to explore different storage conditions in a particular setting, allowing to propose cutoff criteria for the investment in ATES. The nuanced understanding gained with this study offers practical guidance for enhanced efficiency of feasibility studies. It proves that the DGSA methodology can significantly speed up the development of ATES in more complex hydrogeological settings.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"13 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00326-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parametric analysis on the transient two-phase wellbore model applied to the Yangyi high-temperature geothermal field","authors":"Chaofan Chen,&nbsp;Hongwei Zhou,&nbsp;Thomas Nagel,&nbsp;Theo Renaud,&nbsp;Dmitri Naumov,&nbsp;Olaf Kolditz,&nbsp;Haibing Shao","doi":"10.1186/s40517-024-00322-5","DOIUrl":"10.1186/s40517-024-00322-5","url":null,"abstract":"<div><h3>Purpose</h3><p>In high-temperature geothermal fields, interpretation of the dynamic two-phase state inside the production wells under different wellhead conditions are important to effectively use the geothermal heat source. Therefore, the corresponding wellbore models must have the capability to simulate transient flow and energy state in geothermal wellbores, as well as advective and conductive heat and mass interactions with surrounding formation.</p><h3>Methods</h3><p>In this study, a transient two-phase wellbore model is developed and implemented in the open source software OpenGeoSys, to simulate both flow and energy state in the wellbore, as well as advective and conductive heat and mass interactions with surrounding formation. The model is first verified against analytical solutions and numerical results from the open-source simulator FloWell. The model is then further validated with well logging data from the Yangyi geothermal field in Tibet, China.</p><h3>Results</h3><p>Based on the simulation results of the parametric analysis, the conductive heat loss of the high-velocity geothermal production well in the Yangyi geothermal field is found to be limited and the influence can be safely neglected after 8 h of discharge. The flash point location in the wellbore moves upwards for 112 m along with the decrease in fluid enthalpy by 200 kJ/kg. In the wellbore shut-in process, the wellhead pressure decreases with decreasing velocity, while the location of the flash point does not change much. After wellbore shut-in, a two-phase state still exists in the closed wellbore, and the temperature profile is dominated by conductive heat exchange with the surrounding formation. Taking into account the impact of the feed zone, the mass flow rate of the ZK203 well in the Yangyi geothermal field increases from 122.87 to 126.26 t/h when the wellhead pressure decreases from 1.26 to 1.18 MPa.</p><h3>Conclusion</h3><p>The open-source two-phase wellbore model developed and implemented in this work provides preliminary insights into the transition and evolution of the two-phase state in high-temperature production wells considering advective and conductive interactions with the surrounding formation.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"13 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00322-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142925670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ensemble-based assisted history matching of DTS monitoring data in HT-ATES systems: application to a real-life case study","authors":"S. P. Szklarz,&nbsp;D. Dinkelman,&nbsp;N. Khoshnevis Gargar,&nbsp;B. Boullenger,&nbsp;E. Peters,&nbsp;E. G. D. Barros,&nbsp;M. Koenen","doi":"10.1186/s40517-024-00329-y","DOIUrl":"10.1186/s40517-024-00329-y","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Underground heat storage is an important element in accelerating the energy transition. It can significantly contribute to CO&lt;sub&gt;2&lt;/sub&gt; emission reduction and cost savings since it is one of the cheapest forms of energy storage and it enables the seasonal storage of large energy surpluses from sustainable sources, e.g. wind, sun, geothermal. Numerical models are used for the prediction of thermal behavior important in establishing the high efficiency of the high temperature aquifer thermal energy storage (HT-ATES) systems. However, the lack of exact knowledge of the subsurface conditions introduces modeling uncertainty. It is therefore important to employ approaches that reduce subsurface uncertainty. History matching is a methodology where the numerical models are updated to match historical observations that will in turn not only increase understanding of the subsurface but also improve accuracy of the model predictability of future behavior. In this research, models of the first large-scale operational HT-ATES system in Middenmeer, the Netherlands, were used to evaluate the thermal evolution in the storage aquifer and the over- and underburden clay layers. The HT-ATES system, consisting of a hot and warm well, with a monitoring well inbetween, became operational in the summer of 2021. The extensive monitoring program implemented for the first few operational years provided an opportunity to study the performance of such a system from an environmental and operational point of view. A state-of-the-art assisted history matching approach was applied to the first storage cycle, using a coupling between history matching software and the thermal flow simulator. This approach was compared to a more traditional single-model manual history matching method. Rock properties of the aquifer and over- and underburden layers were updated in the randomly generated prior ensemble of models to fit the simulated temperature evolution measured down the monitoring well with the distributed temperature sensing (DTS) data. The observations gathered during the second year of operations were used to validate the accuracy of the prediction capabilities of the updated models. The obtained results indicate the value of history matching to improve understanding of the subsurface conditions for HT-ATES systems and obtain models with better predictability of the future behavior of heat in the storage reservoir and overburden formations. Such improved models are instrumental in providing engineers with a better quantitative grip on the environmentally responsible storage potential and heat deliverability of the target storage site, which is important to achieve cost-effective site-specific design (e.g. number of wells, well placement) and performing operational strategies (e.g. injection/production rates and temperatures) for new HT-ATES systems. Moreover, the benefits of the assisted history matching approach over manual method are highlighted and both approaches a","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00329-y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142870417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Energy efficiency optimization analysis of a ground source heat pump system based on neural networks and genetic algorithms","authors":"Shanming Wei,&nbsp;HaiBo Wang,&nbsp;YanFa Tian,&nbsp;Xubo Man,&nbsp;Yanshi Wang,&nbsp;ShiYu Zhou","doi":"10.1186/s40517-024-00325-2","DOIUrl":"10.1186/s40517-024-00325-2","url":null,"abstract":"<div><p>This paper reports on the performance of a ground source heat pump (GSHP) system located in Shandong Province, China. The system operation data were monitored and collected by a data collection system. According to the analysis of the accumulated operational data, it was found that the GSHP system showed a relative higher COP in cooling season of 2023 than that of 2022 due to the change of supplying water temperature at ground-source side. Based on the analyzed data, a BP neural network model for energy consumption prediction was established. Furthermore, genetic algorithm (GA) was used to optimize the control strategy on the basis of the energy consumption prediction model. Comparison between the artificial experience control strategy and the one optimized by the genetic algorithm was conducted. The results show that the optimization strategy of the genetic algorithm is superior in terms of energy saving, particularly in the load rate higher than 50%, in which, the average energy-saving rate reaches 39.66%. Within the load rate range of 30–50%, the energy-saving rate could also reach 7.84%.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00325-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142844999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical investigation on the influence of groundwater flow on long-term heat extraction performance of deep borehole heat exchanger array","authors":"Xiong Yang,&nbsp;Wanlong Cai,&nbsp;Yongpeng Li,&nbsp;Ming Wang,&nbsp;Yanlong Kong,&nbsp;Fenghao Wang,&nbsp;Chaofan Chen","doi":"10.1186/s40517-024-00330-5","DOIUrl":"10.1186/s40517-024-00330-5","url":null,"abstract":"<div><p>Groundwater convection is commonly observed in real-world projects, particularly in coastal and groundwater-abundant regions. To accurately evaluate the heat extraction capacity of the deep borehole heat exchanger (DBHE) considering groundwater flow, a conduction–convection coupled numerical model of the DBHE is established by OpenGeoSys (OGS) software. Then, the variation of the DBHE circulation temperature and the heat extraction capacity affected by different groundwater conditions, including Darcy velocity, location of the aquifer, and porosity of the aquifer, are quantitatively analyzed. The results show that the porosity and location of the aquifer have a limited effect on the heat extraction capacity of the DBHE. With the given scenario in this study, when the Darcy velocity reaches more than <span>(1times 10^{-7},{{textrm{m}}/{textrm{s}}})</span>, it has a distinguishable effect on the heat extraction capacity of DBHE under the influence of groundwater. In addition, long-term simulations of multiple DBHEs considering the characteristics of the ground pipe network are performed in different directions of groundwater flow. The results indicate that groundwater flow can alleviate cold accumulation around the boreholes, and the thermal plume is pushed much towards the downstream direction. The cross-flow groundwater results in a higher circulation temperature than the parallel flow for the DBHE array. The maximum temperature difference between the two configurations is <span>({1.98},^{circ }{textrm{C}})</span>, which occurs at the end of the 15th operating year based on the given parameters. The results of this study can be used as a guide for project engineers and decision-makers to accurately assess the heat extraction capacity of DBHE and strategize the layout of the DBHE array, taking into account the influence of groundwater flow.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00330-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142859517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel approach for modelling low enthalpy geothermal in deep sedimentary aquifers: a case study of 40 years of production data in the Dogger formation","authors":"Theo Renaud,&nbsp;Joris Popineau,&nbsp;John O’Sullivan,&nbsp;Julien Gasser Dorado","doi":"10.1186/s40517-024-00328-z","DOIUrl":"10.1186/s40517-024-00328-z","url":null,"abstract":"<div><p>Geothermal energy in the Paris urban area has been exploited since the early 1970s. Deep drilling in the Paris sedimentary basin has targeted hot brine in the Dogger formations from a mid-Jurassic carbonate rocks series. More than a hundred wells have been drilled to depths ranging from 1400 to 2000 m and decades of production and reinjection have resulted in variations in the aquifer pressure and temperature in some areas. The regional numerical model discussed herein is aimed at assessing the potential interactions between doublets and for assessing the impact of the addition of more wells in the future. While the integration of a 3D refined geological model into a large-scale reservoir model needs heavy computational resources, local models simplifying the main productive areas into one or two layers surrounded by impermeable units can be used to approximately assess the reservoir characteristics. The modelling of a semi-regional area of the Dogger reservoir in the Southern part of Paris (Cachan/Orly) has been performed, using a conventional double-layer approach to simulate the natural state and production history of the area using the simulator Waiwera, a fast parallel open-source geothermal simulator from the University of Auckland in New-Zealand. Calibration of a natural state model, which describes the conditions before any geothermal operations, has been performed, including an analysis of the impact of boundary condition values on the ability of the model to match the data available in the public domain. The temperature and pressure distributions, instead of being based on geostatistical mapping methods have been obtained from a calibrated natural state model. The implementation of a regional lateral cross flow observed from past studies proved to be essential for matching the measured temperatures and pressures along with variations in the deep heat flux. A calibrated model has been obtained from matching the available production data with mismatches of no more than 1.5 °C. The modelling results confirm the dominance of the shallower productive zone in the aquifers and give insights into the extent of the cooler areas created by the long-term operations. Thus we have used the Dogger reservoir, with multiple data sets available, as a case study for calibrating a semi regional numerical model of a deep sedimentary aquifer used for geothermal direct-use. Our modelling study accounts for the conceptual understanding of the sedimentary aquifer with its heterogeneities and calibrates the numerical model against the measured historical data. Based on the calibrated reservoir model, the pressure and temperature responses in deep productive areas can be determined enabling operators or decision makers to test future strategies for sustainably operating the geothermal resource.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00328-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142859518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Brazilian Curie isothermal mapping: the THERMOMAG model","authors":"Suze N. P. Guimaraes,&nbsp;Beatriz L. de Jesus,&nbsp;Fábio P. Vieira","doi":"10.1186/s40517-024-00321-6","DOIUrl":"10.1186/s40517-024-00321-6","url":null,"abstract":"<div><p>Geothermally, the lithosphere can be defined as the outermost layer of the Earth in which heat is primarily transferred by conduction. It typically includes the crust and upper mantle. Crustal structural provinces are segments of the crust that have the same range of geochronologic ages and thermogeologic histories. The crustal geothermal regime on the continent is determined by many factors, including heat flow, vertical and lateral variations in thermal conductivity, radiogenic heat production, tectonic history, and surface thermal processes. Studying the thermal structure of the crust by geotectonically characterizing the upper lithospheric layer makes it possible to understand the internal heat flow as an energy source potential, which remains unknown due to limited exploration research. This study presents a crustal heat distribution model using direct temperature data and indirect estimates derived from crustal magnetic field information, the THERMOMAG model. The subsurface layers are identified in order to characterize the entire magnetized crust, thus delimiting the Curie surface (isothermal limit of 580 °C), which is directly linked to the exploration of crustal energy resources. Spectral analysis of the aeromagnetic data was used to estimate the depth of the layer related to the deepest crustal sources and their spatial distribution, thus comparing these discoveries with geothermal fields known from direct modeling. The cross-check in the values for the Curie isotherm inserted by the thermomagnetic model allowed a correction in the values obtained indirectly, called the thermomagnetic correction factor (β) which is directly correlated to the amount of data distributed in the different provinces. The results of this model suggest that the greatest Curie depths in Brazil (&gt; 44 km) are located in the São Francisco and Parnaiba provinces, and for the others, the mean values are 23 km. The regions of geothermal anomalies are found essentially in the northwest region of Paraná province, the northern part of Tocantins West province, the south-central part of Tocantins East province, the north-central part of São Francisco province, and the northeast region of Borborema province. The Brazilian structural provinces have thermal conductivity values ranging from <i>2.1</i> to <i>2.7 W/mK</i>.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00321-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142870336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility of coaxial deep borehole heat exchangers in southern California","authors":"Haohua Chen,&nbsp;Ingrid Tomac","doi":"10.1186/s40517-024-00319-0","DOIUrl":"10.1186/s40517-024-00319-0","url":null,"abstract":"<div><p>This paper investigates the feasibility of coaxial deep borehole heat exchanger (CDBHE) applications to the University of California San Diego (UCSD) campus. By collecting different geophysical source data for various formations and well logs around the UCSD campus, a multilayered thermophysical model for the ground on the site is established. Water circulation within a closed coaxial loop system considers the geothermal energy extraction under uncertainty consideration of the unknown deeper layers heat flow gradient as coupled with the variation of pipe insulation properties, flow rates, outer pipe diameter, grout, and depths between 1 and 4 km. A finite-element framework models the Navier–Stokes fluid flow and heat transfer in the CDBHE system, validated with a field test on CDBHE from the literature. Results show that a 4-km CDBHE could produce a thermal power of 600 kW under the optimum geological conditions at the UCSD site: the water flow rate of 2.78 L/s and a ground thermal gradient of 60 ℃/km. Thermal power shares from different layers indicate that deeper formation layers contribute more to the thermal power than the shallower layers because increasing the CDBHE length from 1 to 4 km can lead to a maximum of 900% increase in thermal power and a 50% expansion in thermal plume for a CDBHE with an insulated inner pipe between the upper and lower bound heat flow bounds. An inner pipe with an insulated depth of 2 km produces only 1–6% less power than a fully insulated inner pipe for the 4-km CDBHE, and thus, a partially insulated vacuum-insulated tube (VIT)-plastic inner pipe is suggested as the best practice. Furthermore, the CDBHE thermal power increases by 5% when the grout thermal conductivity increases from 1 to 3.65 W/(K∙m), close to the formation thermal conductivity, and then maintains almost the same, and the 4-km CDBHE with flow rates of 2.78–6.94 L/s at the UCSD site can directly supply a low-temperature heating radiator system for room heating. This study suggests practical ranges for geothermal energy extraction for southern California. A CDBHE with a well-insulated inner pipe of 0.05 W/(m∙K), the thermal power of lower and upper-bound heat flow cases can vary by 60% from the mean. Finally, water as the working fluid is more efficient than CO₂, doubling CDBHE's thermal power. The effects of the investigated factors provide guidelines for future geothermal resource exploitation in southern California.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00319-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142565863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controls of low injectivity caused by interaction of reservoir and clogging processes in a sedimentary geothermal aquifer (Mezőberény, Hungary)","authors":"Ábel Markó,&nbsp;Maren Brehme,&nbsp;Daniele Pedretti,&nbsp;Günter Zimmermann,&nbsp;Ernst Huenges","doi":"10.1186/s40517-024-00317-2","DOIUrl":"10.1186/s40517-024-00317-2","url":null,"abstract":"<div><p>Low injectivity is often experienced in geothermal doublets installed in sandstone reservoirs. This even led to a shutdown of the Mezőberény (Hungary) geothermal site. An on-site campaign was carried out in January 2021 to prepare a stimulation aiming to enhance the transmissivity of the sedimentary reservoir and the near-wellbore zone of this site. Previous studies have concluded that insufficient injectivity may be linked to a high skin effect in the near well-bore zone and pore clogging in combination with the low net sandstone content of the fluvio-deltaic reservoir. A chemical soft stimulation based on the injection of hydrochloric acid (HCl) was successfully used to unclog and recover the well injectivity. Despite such empirical evidence, the geochemical mechanisms leading to both, detrimental formation of clogging and the HCl-driven transmissivity restoration, have not yet been elucidated. This work presents the results of a novel analysis aiming at (a) predicting the dominant type of clogging forming in the near-well bore zone; (b) quantifying the drop in hydraulic conductivity as clogging occurs; and (c) supporting the optimization of the HCl dosage during the chemical soft stimulation. The study is supported by new experimental datasets never presented before from the Mezőberény site and a geochemical model set-up simulating the main mechanisms involved in the clogging and unclogging processes. It is concluded that the biofilm formation was the dominant, while the precipitation of calcite and amorphous ferrihydrite—later reduced to magnetite by microbes—was the secondary clogging mechanism: In the long-term (yearly scale) simulating the hydraulic conductivity showed a decline with forming scales; therefore, biofilm was presumably responsible for the experienced rapid (1 month) clogging. When modelling the chemical stimulation, the estimated amount of precipitated minerals was dissolved already with 2.5 mol of HCl per liter of water (~ 10 m/m%). Therefore, the 20 m/m% of HCl chosen during the field campaign might had a beneficial effect dissolving the potentially higher amount of scaling and/or the carbonate minerals of the matrix near the wellbore. Overall, it is concluded that the chemical and the microbial analyses together with the geochemical model were critical to tailor the remediation attempts and to propose further development or reconstruction of the surface system before going into operation to prevent recurrent impairments. Our findings highlight the importance of interactions of various clogging mechanisms with each other as well as with the reservoir processes and provide approaches to tackle the issue of injectivity drop by characterizing and quantifying their effects.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00317-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Density of pure and mixed NaCl and CaCl2 aqueous solutions at 293 K to 353 K and 0.1 MPa: an integrated comparison of analytical and numerical data","authors":"Ulrike Hoffert,&nbsp;Laurent André,&nbsp;Guido Blöcher,&nbsp;Sylvain Guignot,&nbsp;Arnault Lassin,&nbsp;Harald Milsch,&nbsp;Ingo Sass","doi":"10.1186/s40517-024-00318-1","DOIUrl":"10.1186/s40517-024-00318-1","url":null,"abstract":"<div><p>This study reports on newly acquired density data of synthetically prepared pure and mixed NaCl and CaCl₂ aqueous solutions that span a wide range of geothermally encountered concentrations and mixing ratios. The analytical data are provided for the temperature range of 293–353 K at ambient pressure. For the reproduction of that data, PHREESCALE was used. The predictive potential of this numerical tool regarding the density of geothermal fluids of known composition was the major target herein. As a result, the measured data are in good agreement with previous analytical studies found in the literature. Possible sources of errors are discussed in this paper. Density data of the mixed solutions at temperatures other than ambient are unique and close existing data gaps. The numerical model reproduces the newly measured and already existing density data within an error band of approximately 1%. For further use in geothermal applications, this can be considered an excellent agreement. Moreover, the model yields a direct calculation of density without the need to establish complex empirical equations of state and mixing rules. Finally, sensitivity calculations performed with a thermal–hydraulic (TH) numerical reservoir model demonstrate the required accuracy of fluid density for reliably predicting the long-term performance of deep geothermal energy systems. In terms of the productivity index and the timing of thermal breakthrough it shows that the present analytical and numerical uncertainty in density is small enough to reliably state both reservoir parameters.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00318-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142451068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}