Modeling Highly Buoyant Flows in the Castel Giorgio: Torre Alfina Deep Geothermal Reservoir

The Castel Giorgio-Torre Alfina (CG-TA, central Italy) is a geothermal reservoir whose fluids are hosted in a carbonate formation at temperatures ranging between 120°C and 210°C. Data from deep wells suggest the existence of convective flow. We present the 3D numerical model of the CG-TA to simulate the undisturbed natural geothermal field and investigate the impacts of the exploitation process. The open source finite-element code OpenGeoSys is applied to solve the coupled systems of partial differential equations. The commercial software FEFLOW® is also used as additional numerical constraint. Calculated pressure and temperature have been calibrated against data from geothermal wells. The flow field displays multicellular convective patterns that cover the entire geothermal reservoir. The resulting thermal plumes protrude vertically over 3 km at Darcy velocity of about7⁎10-8 m/s. The analysis of the exploitation process demonstrated the sustainability of a geothermal doublet for the development of a 5 MW pilot plant. The buoyant circulation within the geothermal system allows the reservoir to sustain a 50-year production at a flow rate of 1050 t/h. The distance of 2 km, between the production and reinjection wells, is sufficient to prevent any thermal breakthrough within the estimated operational lifetime. OGS and FELFOW results are qualitatively very similar with differences in peak velocities and temperatures. The case study provides valuable guidelines for future exploitation of the CG-TA deep geothermal reservoir.

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3D magnetotelluric exploration of Sete Cidades Volcano, São Miguel Island, Azores

Interpretation ◽

10.1190/int-2016-0018.1 ◽

2017 ◽

Vol 5 (2) ◽

pp. T219-T230 ◽

Cited By ~ 1

Author(s):

Paulo T. L. Menezes ◽

Jandyr M. Travassos ◽

Adriano J. A. Marçal ◽

Fernando A. Monteiro Santos

Keyword(s):

Geothermal Energy ◽

Energy Demand ◽

Geothermal Field ◽

Geothermal Reservoir ◽

Impedance Tensor ◽

Geothermal System ◽

3D Inversion ◽

High Enthalpy ◽

Reconnaissance Survey ◽

Clay Cap

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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Shallow structure of Los Humeros (LH) caldera and geothermal reservoir from magnetotellurics and potential field data

Geophysical Journal International ◽

10.1093/gji/ggaa338 ◽

2020 ◽

Vol 223 (1) ◽

pp. 666-675

Author(s):

Fernando Corbo-Camargo ◽

Jorge Arzate ◽

Emilia Fregoso ◽

Gianluca Norini ◽

Gerardo Carrasco-Núñez ◽

...

Keyword(s):

Broad Band ◽

Geothermal Field ◽

Geothermal Reservoir ◽

Geothermal System ◽

Common Source ◽

Density Structure ◽

Data Set ◽

Potential Field Data ◽

Gravity Database ◽

Shallow Structure

SUMMARY This study focuses in the analysis of the internal structure of the upper 3 km of Los Humeros (LH) caldera and the relation of electrical and hydrothermal anomalies. For this purpose, we measured, processed and interpreted 78 broad-band magnetotelluric (MT) soundings. We performed a 3-D inversion of the data set (ModEM) using all MT soundings, although only half of the available frequencies per sounding due to limited computed power. We also carried out the 2-D inversions (NLCG) of the invariant determinant along two orthogonal profiles (EW and NS) crossing the caldera structure; their comparison yields similar resistivity and structural models results. The resistivity modelling is complemented with the results of a joint 3-D inversion of an accurate gravity database of 720 stations, and total field aeromagnetic data (SGM) from the caldera crater. The combined results provide novel details about the structure of the shallow geothermal reservoir of the resurgence caldera complex hosting the active hydrothermal system. Density and resistivity models show the existence of a composed crater basin structure separated by an EW high-density structure; the northern basin is associated to the LH crater, whereas the southern basin associates to the emergent Los Potreros (LP) caldera basin. The magnetization model indicates that there is a common source for the magnetic volcanic products observed at the caldera surface, and that the LP fault is the more magnetized fault of the geothermal system. The propylic zoning under the geothermal field, which according to the MT model results has resistivities above ∼100 Ω-m, was extrapolated using this and additional criteria to obtain the distribution of other hypothetical propylitic zones of hydrothermal potential.

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Fluid-driven anthropogenic micro-seismic activity while drilling towards supercritical conditions in the Larderello-Travale geothermal field

10.5194/egusphere-egu2020-5612 ◽

2020 ◽

Author(s):

Domenico Montanari ◽

Riccardo Minetto ◽

Thomas Plànes ◽

Marco Bonini ◽

Chiara Del Ventisette ◽

...

Keyword(s):

Seismic Activity ◽

Central Italy ◽

Causal Link ◽

Geothermal Field ◽

Phase Changes ◽

Critical Conditions ◽

Periodic Pattern ◽

Well Drilling ◽

Geothermal Fluids ◽

Geothermal Wells

<p>This study investigates the seismic activity occurring at the Larderello-Travale geothermal field (LTGF), central Italy, from June 2017 to January 2018. We deployed a network composed of 9 broadband stations around the Venelle 2 well drilling for supercritical fluids. During the experiment, we recognise a group of events that usually occur in swarms and that show a periodic pattern, a narrow frequency band, and almost identical waveforms. Their source is estimated to be located near the well, and their occurrence ceases after about 3 weeks from the conclusion of the drilling. We propose a causal link with the drilling operations where pressure fronts inside the well may promote phase changes and fluid flow across the drilled formations.</p><p>Our study sheds light on the anthropogenic seismic activity at the LTGF. More generally, we show that microseismic activity occurring during drilling in high-pressure and high-temperature conditions can remain at low magnitudes and that geothermal wells targeting geothermal fluids in such systems may be handled safely despite the critical conditions encountered at depth. The drilling of the Venelle 2 well is an encouraging example for the development of geothermal energy in critical conditions.</p>

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Determining the Recoverable Geothermal Resources Using a Numerical Thermo-Hydraulic Coupled Modeling in Geothermal Reservoirs

Frontiers in Earth Science ◽

10.3389/feart.2021.787133 ◽

2022 ◽

Vol 9 ◽

Author(s):

Yifan Fan ◽

Shikuan Zhang ◽

Yonghui Huang ◽

Zhonghe Pang ◽

Hongyan Li

Keyword(s):

Temperature Drop ◽

Geothermal Field ◽

Geothermal Reservoir ◽

Recovery Factor ◽

Coupled Modeling ◽

Geothermal Resources ◽

Geothermal Heating ◽

Sustainable Exploitation ◽

Well Spacing ◽

Recoverable Resources

Recoverable geothermal resources are very important for geothermal development and utilization. Generally, the recovery factor is a measure of available geothermal resources in a geothermal field. However, it has been a pre-determined ratio in practice and sustainable utilization of geothermal resources was not considered in the previous calculation of recoverable resources. In this work, we have attempted to develop a method to calculate recoverable geothermal resources based on a numerical thermo-hydraulic coupled modeling of a geothermal reservoir under exploitation, with an assumption of sustainability. Taking a geothermal reservoir as an example, we demonstrate the effectiveness of the method. The recoverable geothermal resources are 6.85 × 1018 J assuming a lifetime of 100 years in a well doublet pattern for geothermal heating. We further discuss the influence of well spacing on the recoverable resources. It is found that 600 m is the optimal well spacing with maximum extracted energy that conforms to the limit of the pressure drop and no temperature drop in the production well. Under the uniform well distribution pattern for sustainable exploitation, the recovery factor is 26.2%, which is higher than the previous value of 15% when depending only on lithology. The proposed method for calculating the recoverable geothermal resources is instructive for making decisions for sustainable exploitation.

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Methodology Applied for Thickness Selection and Stored Heat Evaluation in Non-producer Geothermal Wells in Order to Its Investment Rescue

Current Journal of Applied Science and Technology ◽

10.9734/cjast/2020/v39i1930796 ◽

2020 ◽

pp. 91-111

Author(s):

Alfonso Aragon- Aguilar ◽

Georgina Izquierdo- Montalvo ◽

Dominic A. Becerra- Serrato ◽

Victor M. Monrroy- Mar

Keyword(s):

Electric Energy ◽

Geothermal Field ◽

Geothermal Systems ◽

Drainage Radius ◽

Heterogeneous Behavior ◽

Water Recharge ◽

Geothermal Wells ◽

Using Data ◽

Heat Calculation ◽

Heat Store

An assessment methodology of stored heat in rock formation surrounding to wellbore in geothermal systems is shown. Due to geothermal systems generally are nested in volcanic rock, it is characteristic its heterogeneous behavior. Proposed methodology starts since zone selection with possibilities of heat store. This methodology is focused to be applied in geothermal reservoirs with tendency to production decline, due to low permeability and unbalance between exploitation and water recharge. Because the high costs of drilling geothermal wells, methodology shown in this work is proposed to be applied in those with production decline or non-producers, in order to rescue its investment. The objective is to select the thickness with heat, evaluate its storage, design the appropriate instrumentation for its recovery, its energy conversion and rescue its investment done. The different designs for energy recovery using non-conventional methods to those, used habitually are reviewed. Each one of the variables for stored heat calculation was determined using technical tools of reservoir engineering. A parametric analysis about variables sensitivity (porosity and drainage radius) for determining thermal energy and corresponding electric energy of analyzed rock volume is done. Practical application of this methodology was carried out using data of one of wells of Los Humeros Mexican geothermal field.

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An Approach for Estimating Geothermal Reservoir Productivity under Access Limitations Associated with Snowy and Mountainous Prospects

10.5772/intechopen.96314 ◽

2021 ◽

Author(s):

Mitsuo Matsumoto

Keyword(s):

Early Time ◽

Geothermal Field ◽

Geothermal Reservoir ◽

Well Testing ◽

Reservoir Pressure ◽

New Approach ◽

Frequency Distributions ◽

Arbitrary Time ◽

Active Exploration ◽

Time Limitations

This chapter describes an approach to estimate reservoir productivity during the active exploration and development of a geothermal prospect. This approach allows a reservoir model to be updated by overcoming the severe time limitations associated with accessing sites for drilling and well testing under snowy and mountainous conditions. Performed in parallel with the conventional standard approach, the new approach enables us to obtain a first estimate of the reservoir productivity at an early time and to make successful project management decisions. Assuming a practical geothermal field, the procedures of the new approach are demonstrated here in detail. Finally, frequency distributions for the expected production rates and changes in the reservoir pressure at an arbitrary time are obtained during an assumed operational period.

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Characterization of a carbonate geothermal reservoir using rock-physics-guided deep neural networks

The Leading Edge ◽

10.1190/tle40100751.1 ◽

2021 ◽

Vol 40 (10) ◽

pp. 751-758

Author(s):

Fabien Allo ◽

Jean-Philippe Coulon ◽

Jean-Luc Formento ◽

Romain Reboul ◽

Laure Capar ◽

...

Keyword(s):

Neural Networks ◽

Seismic Data ◽

Deep Neural Networks ◽

Synthetic Data ◽

Rock Physics ◽

Seismic Inversion ◽

Geothermal Reservoir ◽

Rock Properties ◽

Hybrid Techniques ◽

Geothermal Wells

Deep neural networks (DNNs) have the potential to streamline the integration of seismic data for reservoir characterization by providing estimates of rock properties that are directly interpretable by geologists and reservoir engineers instead of elastic attributes like most standard seismic inversion methods. However, they have yet to be applied widely in the energy industry because training DNNs requires a large amount of labeled data that is rarely available. Training set augmentation, routinely used in other scientific fields such as image recognition, can address this issue and open the door to DNNs for geophysical applications. Although this approach has been explored in the past, creating realistic synthetic well and seismic data representative of the variable geology of a reservoir remains challenging. Recently introduced theory-guided techniques can help achieve this goal. A key step in these hybrid techniques is the use of theoretical rock-physics models to derive elastic pseudologs from variations of existing petrophysical logs. Rock-physics theories are already commonly relied on to generalize and extrapolate the relationship between rock and elastic properties. Therefore, they are a useful tool to generate a large catalog of alternative pseudologs representing realistic geologic variations away from the existing well locations. While not directly driven by rock physics, neural networks trained on such synthetic catalogs extract the intrinsic rock-physics relationships and are therefore capable of directly estimating rock properties from seismic amplitudes. Neural networks trained on purely synthetic data are applied to a set of 2D poststack seismic lines to characterize a geothermal reservoir located in the Dogger Formation northeast of Paris, France. The goal of the study is to determine the extent of porous and permeable layers encountered at existing geothermal wells and ultimately guide the location and design of future geothermal wells in the area.

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Origin of continuous hydrogen flux in gas manifestations at the Larderello geothermal field, Central Italy

Chemical Geology ◽

10.1016/j.chemgeo.2021.120564 ◽

2021 ◽

Vol 585 ◽

pp. 120564

Author(s):

Mahmoud Leila ◽

Dan Lévy ◽

Anne Battani ◽

Luigi Piccardi ◽

Branimir Šegvić ◽

...

Keyword(s):

Central Italy ◽

Geothermal Field ◽

Hydrogen Flux

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

Water ◽

10.3390/w11081631 ◽

2019 ◽

Vol 11 (8) ◽

pp. 1631

Author(s):

Fan ◽

Pang ◽

Liao ◽

Tian ◽

Hao ◽

...

Keyword(s):

High Temperature ◽

Tibetan Plateau ◽

Heat Source ◽

Chloride Concentration ◽

Geothermal Field ◽

Geothermal Water ◽

Helium Isotope ◽

Geothermal System ◽

The Tibetan Plateau ◽

Geothermal Waters

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

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Geochemical response of deep geothermal processes in the Litang region, Western Sichuan

Energy Exploration & Exploitation ◽

10.1177/0144598718812550 ◽

2018 ◽

Vol 37 (2) ◽

pp. 626-645

Author(s):

Wei Zhang ◽

Guiling Wang ◽

Linxiao Xing ◽

Tingxin Li ◽

Jiayi Zhao

Keyword(s):

Groundwater Recharge ◽

Hot Springs ◽

Cold Water ◽

Isotope Analysis ◽

Geothermal Field ◽

Geothermal System ◽

Calcite Dissolution ◽

Western Sichuan ◽

Geothermal Fields ◽

Positive Correlations

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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