•Solute transport modeling of the Soultz-sous-Forêts EGS•Joint analysis of different hydraulic and geophysical experiments•Hydraulic characterization of the pathways between the wells within the ...reservoir•Reevaluation of the fracture-controlled flow field in the EGS
The Enhanced Geothermal System in Soultz-sous-Forêts, located in the geothermal favorable Upper Rhine Graben, is a fracture-controlled reservoir that was highly investigated in the last decades generating a huge geoscientific database. Numerical reservoir models use this database to simulate the operation of the subsurface heat exchanger, yet suffer from simplifications regarding the transfer of experimental into model data, dimensional extension, and computational power and efficiency. The new extensive transient 3D simulations, based on geophysical, geological and hydraulic data, highlight the hydraulic and transport feedback of the Soultz EGS due to convective and advective fluid flow. Developed with the goal of simulating the vast tracer test data during the reservoir-testing phase in 2005, the finite element model is focusing on the main fractured zones, which connect the wells in the deep reservoir. It comprises 13 major hydraulically active faults and fractures in a 13 × 11 x 5 km extending model domain, as well as open-hole sections of the wells GPK1 to GPK4 and their casing leakages. The simulation of the tracer experiment confirms the strong heterogeneity of the reservoir and highlights the importance of a potential fractured zone, hydraulically separating the reservoir in a northern (GPK1 to 3) and southern section (GPK4). This zone tends to connect the reservoir to the main fault system by hydraulically separating GPK4 from the other wells. The calibration and sensitivity analyses provide a unique, broad understanding of the reservoir flow zones providing information on the extension of the Soultz reservoir in the future and on the fluid pathways in the deep subsurface of the Upper Rhine Graben.
For successful geothermal reservoir exploration, accurate temperature estimation is essential. Since reservoir temperature estimation frequently involves high uncertainties when using conventional ...solute geothermometers, a new statistical approach is proposed. The focus of this study is on the development of a new multicomponent geothermometer tool which requires a significantly reduced data set compared to existing approaches. The method is validated against reservoir temperature measurements in the Krafla and the Reykjanes geothermal systems. A site-specific basaltic mineral set was selected as the basis to compute the equilibrium temperatures. These high-enthalpy geothermal reservoirs are located in the neo-volcanic zone of Iceland where the fluid temperatures are known to reach up to 350 °C at a depth of 2000 m. During ascent, the fluid composition is prone to changes as well as possible phase segregation due to depressurization and boiling. Therefore, to reduce the uncertainty of temperature estimations, reservoir temperature conditions are numerically reconstructed with sensitivity analyses considering pH, aluminium concentration, and steam loss. The evaluation of the geochemical data and the sensitivity analyses were calculated via a numerical in-house tool called MulT_predict. In all cases, the temperature estimations match with the in situ temperatures measured at Krafla and Reykjanes. The development of this method tends to be a promising and precise tool for reservoir temperature estimation. The developed methodology is a fast and easy-to-handle exploration tool that can be applied to standard geochemical data without the need for a sophisticated gas analysis yet obtaining very accurate results.
The determination of reservoir temperatures represents a major task when exploring geothermal systems. Since the uncertainties of classical solute geothermometry are still preventing reliable ...reservoir temperature estimations, we assess the performance of classical geothermometers and multicomponent geothermometry by applying them to fluids composed from long-term batch-type equilibration experiments and to fluids from natural geothermal springs in the Villarrica area, Southern Chile. The experiments, weathering two reservoir rock analogues from the Villarrica area, highlight a strong impact of reservoir rock composition on the fluid chemistry and, consequently, on calculated in situ temperatures. Especially temperatures calculated from classical solute geothermometry are strongly affected. Multicomponent geothermometry is obviously more robust and independent from rock composition leading to significantly smaller temperature spreads. In a sensitivity analysis, the dilution of geothermal fluid with surficial water, the pH and the aluminum concentration are anticipated to be the factors causing underestimations of reservoir temperatures. We quantify these parameters and correct the results to obtain realistic in situ conditions. Thus, enabling the application of the method also on basis of standard fluid analysis, our approach represents an easy-to-use modification of the original multicomponent geothermometry leading to very plausible subsurface temperatures with significantly low scattering.
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Skeletal muscle requires functional mitochondria to provide it with its energy needs. The quality of the organelle is dependent on the synthesis of new mitochondria and the degradation ...of those that are no longer operative, via the mitophagy pathway. Current research is examining mitophagy impairments at the autophagosome level, yet little is known about the degradation of the organelle at the level of the lysosome. Dysfunctional mitochondria produce high amounts of ROS and have a lower membrane potential, targeting them for degradation. Tagged mitochondria are engulfed in autophagosomes, which then fuse with lysosomes containing hydrolytic enzymes. The fusion of the lysosome and autophagosome is mediated by the lysosomal protein Lamp2, and is essential for the final stage of mitophagy. The purpose of this project is to evaluate the consequences of Lamp2 deficiency on mitochondrial and lysosomal proteins, as well as potential compensatory signaling responses within muscle. Gastrocnemius and quadriceps muscles of Lamp2 KO mice, compared to WT mice, were used for western blotting and enzymatic analyses. Lamp2 KO mice exhibited a significant 1.4‐fold increase in the adapter protein p62, responsible for tethering the autophagosome to the dysfunctional cargo. Similarly, the LC3‐II to LC3‐I ratio was increased by 2.4‐fold in mice lacking Lamp2. COX activity, a measurement of mitochondrial content, was also elevated by 1.3‐fold in KO mice compared to WT counterparts. These results suggest that the absence of Lamp2 leads to an accumulation of autophagosomes containing mitochondria that are not properly degraded. Protein levels of Beclin1 and the E3 ubiquitin ligase Parkin, were augmented in KO mice, possibly in an attempt increase signaling towards autophagosome formation, and the targeting of dysfunctional mitochondria. TFEB, the master regulator of lysosomal and autophagy genes, was increased 2.2‐fold in KO mice compared to WT animals. Interestingly, mTOR phosphorylation was also increased 2‐fold in KO mice. This activation of mTOR suggests that the elevated TFEB levels are largely confined to the cytosol, and may be less transcriptionally active. However, a downstream target of TFEB, Cathepsin D was increased in KO mice, but no changes were observed in the lysosomal marker V‐ATPase between genotypes. PGC‐1a, the master regulator of mitochondrial biogenesis was elevated by 1.8‐fold in the KO mice, suggesting increased signaling towards mitochondrial biogenesis. However, levels of Transcription factor A (Tfam) were similar between genotypes, suggesting that the absence of Lamp2 may dysregulate the coordinated expression of nuclear and mtDNA encoded gene products. This was evident from an increase in UQCRC2, a nuclear‐derived protein, with no changes observed in mtDNA encoded COXI. Thus, these data suggest that Lamp2 is required for the clearance of mitochondria. In its absence, mitochondrial degradation is defective, initiating compensatory signaling responses to mitochondrial biogenesis and autophagy induction to promote mitochondrial turnover and the reestablishment of a high quality mitochondrial pool.
Preferential fluid pathways along regional fault systems are crucial for the spatial localization of volcanic and geothermal manifestations. Differences in electric properties of fluids and ...hydrothermal alteration products against the unaltered matrix allow for visualization of such pathways. Unfavorable geometry for 2-D inversion resulting from the fluid pathways in regional faults often being aligned along the geo-electric strike can be overcome by using 3D inversion of magnetotelluric data. For a section in the 1400 km long Liquiñe-Ofqui Fault System (LOFS), we demonstrate the potential of 3-D inversion of magnetotelluric data for visualization of fluid pathways.
Six out of eight electric resistivity anomalies at intermediate depth are connected to volcanic or geothermal surface manifestations. Deep and highly conductive anomalies are detected in the vicinity of the volcanic chain and where the LOFS is crosscut by a fault that belongs to the Andean transversal fault system. The anomaly related to the fault crossing reveals a vertical pathway extending to the surface. Phase tensor analyses indicate a structural origin of the latter anomaly that may be connected to a line of volcanic cones that occurs in the NE of the Villarrica Volcano.
•3-D inversion created the first complete visualization of preferential fluid pathways.•Structural control of preferential magmatic and geothermal fluid pathways•Connection at surface low resistivity bodies with the fault-related system•Results suggest that damage zones may provide optimal vertical pathways.
•Application of solute geothermometer often yield large uncertainties (up to 200 K).•Improvement approach of SiO2 and Na-K geothermometers using laboratory experiments and numerical ...modeling.•Correction of site-dependet effects (reservoir lithology, pH value, dilution).•Strongly converging SiO2 and Na-K temperatures (≤10 K).
Solute geothermometry often leads to a broad range and often inconsistent calculated reservoir temperatures, in particular when exploring geothermal systems, where only limited information (geology, borehole data etc.) is available. The application of different Na-K and SiO2 geothermometer, the most widely used methods, not uncommonly lead to deviations of results by up to 200 K for one sample.
In this study, the most effective interfering factors for these geothermometer applications are identified. A multi-step approach is proposed, combining experimental and numerical methods with specific fluid characterization to quantify these factors and to transfer these findings to the natural system enabling the correction of temperatures to realistic in-situ values.
Taking into account dilution with surface water, a chlorofluorocarbon concentration based mixing model was set up to correct analysed SiO2 concentrations to original in-situ concentrations. A numerical model was used to determine the in-situ pH, which is highly sensitive to silica solubility. Results from long-term laboratory equilibration experiments were evaluated to identify the reservoir type dependent equilibrated SiO2 polymorph.
In the case of the Na-K geothermometer, it is shown that the Na+/K+ concentration ratio in fluids is obviously not unequivocally controlled by temperature but is also dependent upon reservoir rock composition. Thus, different reservoir lithologies lead to different equilibration states in terms of Na+/K+. This is obviously one reason for the existence of the large number of different Na-K geothermometers. By modelling the stability of the Na+/K+ ratio governing feldspars, albite and orthoclase, we suggest a method that reveals the Na+/K+ equilibration state for each fluid supporting the allocation of the appropriate geothermometer equation.
The improvement procedure is demonstrated in a case study evaluating fluid data of geothermal springs from the Villarrica geothermal system, Southern Chile. It is shown that initially highly scattered results strongly converge after corrections, leading to a substantial improvement in in-situ temperature estimations with small deviations of ≤10 K between SiO2 and Na-K geothermometers. Also absolute temperature calculated for each spring in the study area, ranging from 84 to 184 °C agree well (within ΔT <20 K) with results of multicomponent geothermometry temperatures reported in a previous work.
In the present study, we combined stable isotopes and anthropogenic tracers to investigate the origin, residence times, and evolution of thermal waters in the Lonquimay-Tolhuaca Volcanic Complex ...(LTVC) of the southern Chilean Andes. A total of 20 water samples from springs discharging at a broad range of temperatures (8–96 °C) were collected and analyzed for major ion geochemistry, stable isotope ratios (δ2H, δ18O, δ13CTDIC), dissolved chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF6). In addition, we compiled all available data on the isotopic composition of precipitation in the region to derive the local meteoric water line. Coupled with a Rayleigh-fractionation model of precipitation, we provide constraints on the elevation at which infiltration and recharge to the system is produced. δ13CTDIC values are consistent with the bulk of dissolved inorganic carbon being derived from the addition of soil CO2 to an atmospheric source, while magma degassing and boiling processes are evidenced in samples discharging directly on the flanks of volcanoes. The isotopic composition of thermal water, once heated at depth, is further modified by CO2 degassing and carbonate precipitation during ascent. All geothermal samples contain low but detectable concentrations of CFC-11, CFC-12, CFC-113, and SF6, suggesting the addition of only a small fraction (2–22%) of modern meteoric water. The discharge temperature of naturally outflowing springs in the LTVC correlates directly with the age distribution of the water samples. This difference in residence times is attributed to the distinct subsurface circulation pathways of each water type—i.e., the shallow, diffuse flow of cold groundwater vs. the deep, focused circulation of thermal water along fault zones. Conduit flow along high vertical permeability networks allows hydrothermal fluid to remain relatively unmixed with shallow meteoric water during ascent. Data from this study confirm that fault-fracture meshes with different orientations exert a first order control on the residence times, ascent, and mixing rates of thermal waters in this segment of the Andean Cordillera, thus modulating their chemical and isotopic signature. Additionally, our results show that the combined use of conventional hydrogeochemical and isotopic data with environmental tracers, including anthropogenic CFCs and SF6, is a powerful tool to better understand the dynamics of geothermal systems.
•Different circulation pathways modulate residence times and chemical signature of fluids.•High vertical permeability fault-fracture networks allow thermal waters to remain undiluted during ascent.•CFCs and SF6 are powerful tools to understand the dynamics of geothermal systems.
The extraction of rare metals like lithium (Li) from geothermal fluids is a promising alternative to conventional mining. Membrane distillation (MD) could support energy-efficient fluid treatment ...enabling further freshwater production. For the operation of geothermal plants and MD uncontrolled precipitation of silica (Si) represents a major hurdle. Herein, we demonstrate the transfer of a Si treatment from lab to field demonstrator scale, tested under conditions of an operating geothermal power plant.
For the treatment, lime precipitation was chosen showing good Si reduction rates using artificial fluids. The high alkaline conditions of this process (pH > 10) in combination with the high salinities of the geothermal brines (TDS > 100 g/L) are transferred into real geothermal environment with a newly developed numerical design calculation. The resulting demonstrator consists of three major process steps - 1) Si-reduction, 2) liquid/solid separation, and 3) post-concentration using MD. The Si treatment efficiently reduced 98 % of Si in <5 min reaction time, without influencing the lithium concentration negatively. The MD resulted in Li concentrations of ∼500 mg/L while producing fresh water. Beyond the approval of the concept, neuralgic points for improvement were identified expanding fundamental knowledge about the material use of geothermal fluids.
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•Geothermal brines can contain high concentrations of raw materials such as Lithium.•Mineral scaling impedes combined geothermal energy and brine treatment processes.•Chemical brine treatment enables use of membrane distillation in geothermal cycles.•Numerical design simulation facilitates transferring the process to power plants.•Demonstrator is developed and continuously operated in a geothermal power plant.
In murine and canine animal models, mutations in the Arylsulfatase G gene (ARSG) cause a particular lysosomal storage disorder characterized by neurological phenotypes. Recently, two variants in the ...same gene were found to be associated with an atypical form of Usher syndrome in humans, leading to visual and auditory impairment without the involvement of the central nervous system. In this study, we identified three novel pathogenic variants in ARSG, which segregated recessively with the disease in two families from Portugal. The probands were affected with retinitis pigmentosa and sensorineural hearing loss, generally with an onset of symptoms in their fourth decade of life. Functional experiments showed that these pathogenic variants abolish the sulfatase activity of the Arylsulfatase G enzyme and impede the appropriate lysosomal localization of the protein product, which appears to be retained in the endoplasmic reticulum. Our data enable to definitely confirm that different biallelic variants in ARSG cause a specific deaf‐blindness syndrome, by abolishing the activity of the enzyme it encodes.
Usher syndrome (USH) is a genetic disease characterized by progressive retinal blindness and hearing impairment. It is classically subdivided in three subtypes, defined mostly by the magnitude and the age of onset of patients' auditory deficit. Recently, an atypical form of this syndrome (type IV), characterized by a late onset of both visual and auditory symptoms, has been described. In this work, we identify three novel pathogenic variants associated with USH type IV in the gene ARSG, encoding the Arylsulfatase G enzyme. By functional experiments we also show that these mutations abolish the sulfatase activity of the protein. In addition, mutant enzymes seem to lose their canonical lysosomal localization and are instead retained in the endoplasmicreticulum.
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