Predictions of Rock Temperature Evolution at the Lahendong Geothermal Field by Coupled Numerical Model with Discrete Fracture Model Scheme

The comprehensive exploitation of geothermal fields has an impact on the productivity of the reservoirs. To realize sustainable steam production, changes in the rock temperature need to be predicted and controlled. A coupled thermo-hydro-mechanical (THM) model employing COMSOL Multiphysics was proposed to study the characteristics of heat transfer, fluid flow, and solid deformation at the Lahendong geothermal field, in North Sulawesi, Indonesia. The numerical results were compared with analytical and measured data in order to validate the numerical simulation. Based on the results, the predicted temperatures of the production wells showed significant decrease with the production time. In addition, a reduction in the reservoir temperature leads to lower specific gross electrical power within the production well, which should significantly reduce the sustainability of the power plant.

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Fluid activity detection in geothermal areas using a single seismic station by monitoring horizontal-to-vertical spectral ratios

Scientific Reports ◽

10.1038/s41598-021-86775-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kyosuke Okamoto ◽

Hiroshi Asanuma ◽

Hiro Nimiya

Keyword(s):

Carbon Capture ◽

Seismic Station ◽

Carbon Capture And Storage ◽

Fluid Flows ◽

Temporal Variations ◽

Geothermal Field ◽

Spectral Ratios ◽

Subsurface Structures ◽

Geothermal Fields ◽

Single Station

AbstractSubsurface structure survey based on horizontal-to-vertical (H/V) spectral ratios is widely conducted. The major merit of this survey is its convenience to obtain a stable result using a single station. Spatial variations of H/V spectral ratios are well-known phenomena, and it has been used to estimate the spatial fluctuation in subsurface structures. It is reasonable to anticipate temporal variations in H/V spectral ratios, especially in areas like geothermal fields, carbon capture and storage fields, etc., where rich fluid flows are expected, although there are few reports about the temporal changes. In Okuaizu Geothermal Field (OGF), Japan, dense seismic monitoring was deployed in 2015, and continuous monitoring has been consistent. We observed the H/V spectral ratios in OGF and found their repeated temporary drops. These drops seemed to be derived from local fluid activities according to a numerical calculation. Based on this finding, we examined a coherency between the H/V spectral ratios and fluid activities in OGF and found a significance. In conclusion, monitoring H/V spectral ratios can enable us to grasp fluid activities that sometimes could lead to a relatively large seismic event.

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Using the Paratunsky geothermal field to provide heating for Kamchatka

Вулканология и сейсмология ◽

10.31857/s0203-03062019221-33 ◽

2019 ◽

pp. 21-33

Author(s):

A. V. Kiryukhin ◽

N. B. Zhuravlev

Keyword(s):

Waste Water ◽

Thermal Energy ◽

Thermal Water ◽

Discharge Rate ◽

Local Heating ◽

Geothermal Field ◽

Heat Energy ◽

Heating Systems ◽

Geothermal Fields ◽

Potential Market

The Paratunsky geothermal field has been in operation since 1964, mostly in a self-flowing mode, with a discharge rate of approximately 250 kg/s of thermal water at temperatures of 70–90°С (47 Mw, with the waste water having a temperature of 35°С). The water drawn from the field is used for local heating, spa heating, and for greeneries in the villages of Paratunsky and Termal’nyi (3000 residents). The potential market of thermal energy in Kamchatka includes Petropavlovsk-Kamchatskii (180000 residents), Elizovo (39 000), and Vilyuchinsk (22 000). The heat consumption in the centralized heating systems for Petropavlovsk-Kamchatskii is 1 623 000 GCal per annum (216 Mw). A thermohydrodynamic model developed previously is used to show that the Paratunsky geothermal reservoir can be operated in a sustainable mode using submersible pumps at an extraction rate of as much as 1375 kg/s, causing a moderate decrease in pressure (by no more than 8 bars) and temperature (by no more than 4°С) in the reservoir. Additional geothermal sources of heat energy may include the Verkhne-Paratunsky and Mutnovsky geothermal fields.

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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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Chemical and isotopic characterization of the thermal fluids emerging along the North–Northeastern Greece

Scientific Reports ◽

10.1038/s41598-021-95656-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

E. Dotsika ◽

P. Dalampakis ◽

E. Spyridonos ◽

G. Diamantopoulos ◽

P. Karalis ◽

...

Keyword(s):

Geothermal Field ◽

Chemical Compositions ◽

Geothermal Systems ◽

High Enthalpy ◽

Thermal Fluids ◽

The North ◽

Geothermal Fields ◽

West Part ◽

Distinct Source ◽

Isotopic Characterization

AbstractHydrochemical and isotopic characteristics of fluids from major geothermal fields of middle/low temperature in N/NE Greece are examined [basins: Strymon River (SR), Nestos River Delta (ND), Xanthi–Komotini (XK), Loutros–Feres–Soufli (LFS) and Rhodope Massif]. The geodynamic context is reflected to isotopic/chemical composition of fluids, heat flow values and elevated CO2 concentrations in emitted fluids. B and Li are derived from leaching of the geothermal systems hosting rocks. δ18OH2O, δ18OSO4, δ13CCO2 values and chemical compositions of Cl, B and Li of geothermal discharges suggest two distinct source fluids. Fluids in SR exhibit high B/Cl and Li/Cl ratios, suggesting these constituents are derived from associated magmas of intermediate composition (andesitic rocks). Geothermal discharges in LFS exhibit low B/Cl and Li/Cl ratios, implying acid (rhyolitic) magmatism. δ13CCO2 and CO2/(CO2 + 105He) ratios in the west part, suggest fluids affected by addition of volatiles released from subducted marine sediments. For the eastern systems, these ratios suggest gas encountered in systems issued from mixing of crustal and mantle-derived volatiles. Isotopic geothermometers reflect, for the same direction, equilibrium processes more (LFS, XK) or less (SR) pronounced and discriminate the geothermal field from low to middle [SR, ND (Erasmio)] and middle to high enthalpy [ND (Eratino), LFS, XK].

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Seismic noise cancellation in a geothermal field

Geophysics ◽

10.1190/1.1442979 ◽

1991 ◽

Vol 56 (10) ◽

pp. 1677-1680 ◽

Cited By ~ 2

Author(s):

D. B. Harris ◽

S. P. Jarpe ◽

P. E. Harben

Keyword(s):

Seismic Noise ◽

Noise Suppression ◽

Noise Cancellation ◽

Geothermal Field ◽

Monitoring Site ◽

High Background ◽

Reflection And Refraction ◽

Geothermal Fields ◽

Passive Seismic ◽

Adaptive Noise

High background seismic noise due to process machinery in production oil or geothermal fields can present a major problem for active seismic studies such as reflection and refraction surveys and passive seismic studies such as microearthquake monitoring. The general noise suppression problem is a difficult one since process noise may be due to a large number of sources distributed over a large region. In some situations, one or a few sources may dominate the noise field locally, presenting an opportunity for noise suppression by cancellation. In this note we describe an application of adaptive noise cancellation (Widrow, et al., 1975) in which we attempt to suppress noise recorded at a primary monitoring site using reference noise recorded at a major nearby noise source.

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A STUDY OF FIELD GEOTHERMAL POWER POTENTIAL & THERMODYNAMIC CONCEPTS OF PROSPECTIVE BINARY POWER CYCLE BASED GEOTHERMAL POWER PLANT FOR TATAPANI GEOTHERMAL FIELD.

June-2020 - International Journal of Engineering Sciences & Research Technology ◽

10.29121/ijesrt.v9.i12.2020.11 ◽

2020 ◽

Vol 9 (12) ◽

pp. 90-104

Keyword(s):

Power Plant ◽

Power Plants ◽

Exergy Analysis ◽

Geothermal Field ◽

Flow Diagram ◽

Exergy Destruction ◽

Geothermal Power Plant ◽

Power Cycle ◽

Geothermal Fields ◽

Geothermal Power

Tatapani Geothermal field is one of the most promising low-enthalpy geothermal fields in central India, located on Son-Narmada lineament in the state of Chhattisgarh, India. The Tatapani geothermal field geological, geo-chemical & reservoir data has been compiled and analysed for evaluating true power potential & better understanding of the field. The low enthalpy geothermal reservoirs can be utilized for power production using Organic Rankine Cycle (ORC) or binary power cycle. Based on previous research works done, the Tatapani geothermal field has been found to be very prospective and has got huge potential for power generation. The binary power cycle has been studied in detail along with thermodynamic concepts. In addition, similar low enthalpy geothermal power plants (conceptual & existing both) have been thoroughly studied in order to understand the concepts and methodology to perform technical feasibility based on thermodynamic and exergy analysis. The literature review covers the previous works done on Tatapani geothermal field including works on other geothermal fields in India along with previous research works for Thermodynamic & Exergy Analysis carried-out for binary geothermal power plants across the world for similar low enthalpy prospects. The methods of performing thermodynamic and exergy analysis for a potential geothermal power plant has been studied and compared. Exergy analysis highlights the areas of primary exergy destruction at various plant components and can be illustrated in the form of exergy flow diagram. The loss of exergy indicates the potential reasons for the inefficiencies within a process and exergic efficiency as conversion of input heat energy from the brine in to useful work output. The exergic efficiencies can be calculated for each component along with exergy destruction. The detailed study has been conducted in order to gather the knowledge regarding conducting the feasibility of setting up binary geothermal power plant at Tatapani from technical point of view using thermodynamic concepts.

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THE APPLICATION OF THE TRANSIENT EM METHOD INTO THE GEOTHERMAL FIELD EXPLORATION

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.16465 ◽

2004 ◽

Vol 36 (3) ◽

pp. 1224

Author(s):

Π. Κάρμης ◽

Γ. Βαργεμέζης ◽

Η. Παπαδόπουλος ◽

Π. Τσούρλος

Keyword(s):

Hot Springs ◽

Geothermal Field ◽

Fluid Temperature ◽

Geothermal Fluid ◽

Geothermal Fields ◽

Em Method ◽

Time Domain Electromagnetic ◽

Tem Method ◽

The Time Domain ◽

First Time

In this work we examine the potential of the time-domain electromagnetic method (Transient EM) in the exploration of geothermal field and the study of the geological environment. The method was applied in the geothermal field of Aristino (Alexandroupolis), westwards of the Traianoupolis, where the known hot springs exist. The EM method and more specifically magnetotellurics (MT), it has been applied in the past in Greece by various researchers, but it is the first time the TEM method is applied for geothermal exploration purposes. As it has been shown by previous works, in the wider region of Aristino an important geothermal field is developed, with geothermal fluid temperature of 30°-90° and high content of dissolved salts of 10gr/lt. These factors result to the appearance of highly conductive geoelectrical anomalies which are directly related to the geothermal field. The existence of two drillholes in the region allowed the calibration and the control of the effectiveness of the TEM method. The geophysical survey has delimited the area of local geothermal interest that is formed by hot aquifer at a relatively shallow depth, extended North of Aristino and between the main faults of the region. The two main faults are responsible for the creation of a tectonic graben in the intermediary region and the development of a highly conductive formation which correlates well with the hot aquifer tank. The geothermal fluid circulates through the faulting system having high temperature caused by the contact with magmatic masses. The application of TEM proved the operational advantages of the method in the geothermal field exploration. The relatively limited number of TEM soundings presented here does not allow the export of safe conclusions regarding the geothermal field of the wider region, although the evaluation of results based on the geological and geoelectrical data of the region is extremely encouraging and justifies the use of the TEM method in the systematic study and mapping of geothermal fields.

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Geochemical Mapping of Sulfur Within Olkaria Geothermal Field, Kenya

International Journal of Scientific Research in Science Engineering and Technology ◽

10.32628/ijsrset20737 ◽

2020 ◽

pp. 55-61

Author(s):

Muhanga Joel Joseph ◽

Sang Paul K. Magut ◽

Onyancha Douglas Okerio

Keyword(s):

Chemical Species ◽

Secondary Data ◽

Ring Structure ◽

Geothermal Field ◽

Volcanic Complex ◽

Geothermal Systems ◽

Geochemical Mapping ◽

Production Wells ◽

Correlation Parameters ◽

Different Color

This research paper focuses on the geochemical mapping of Sulfur to characterize the Olkaria geothermal field, a field associated with geothermal power generation in the northeast of Nairobi. The current geochemical methods used are CO2 and N2 however, a discrepancy associated with the biogenic sources of CO2 renders it less reliable. Sulfur in geothermal systems is magmatic, hence its utilization can help solve these discrepancies. The study utilized sulfur present in the geothermal well waters to identify the main features of a magmatic hydrothermal system, their distribution within the Olkaria volcanic complex and how they relate with the Olkaria structures. Secondary data of the concentrations of H2S and SO4 2- was used for mapping using ArcMap tool within ArcGIS. The distribution of the magmatic H2S facilitated the mapping of the possible up-flow zones and the heat sources within the study area. SO4 2- was used to map possible recharge zones within the study area. The mappings, that is, the up-flow zones, the heat source and the recharge zones are important, because they increase knowledge on where exactly to drill production wells, make up wells and the reinjection wells. Geochemical mapping performed on other fluid chemical species such as CO2, Cl-, N2, as well as the temperature, facilitated the correlation with the sulfur concentration variations. The distribution of various concentrations of sulfur as well as the correlation parameters were shown by different color scales on the geochemical maps. From the maps, the field-scale distributions, enabled the visualization of which faults establish the fluid ascension areas and which are more closely related to recharge zones. The findings indicate that up-flow zones were affiliated to the NW-SE trending faults as well as the Olkaria Fault while the recharge zones were associated with the Gorge farm fault, the ring structure and the Ololbutot fault. Geochemical mapping of Sulfur proved to be an effective method in the characterization of a geothermal field. Its utilization to complement conventional methods, improves precision for well siting. It should therefore, not be ignored during exploration campaign.<

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Determining seismic shear-velocity from ambient noise sources at regional and local scales

10.26686/wgtn.17067788.v1 ◽

2021 ◽

Author(s):

◽

Francesco Civilini

Keyword(s):

Surface Wave ◽

Ambient Noise ◽

Shear Velocity ◽

Volcanic Field ◽

Geothermal Field ◽

Near Surface ◽

Velocity Models ◽

Geothermal Fields ◽

Cross Correlations ◽

Velocity Changes

We present three projects that use different bandwidths of the ambient noise spectrum to solve geophysical problems. Specifically, we use signals within the noise field to determine surface and shear wave velocities, image the shallow and deep crust, and monitor time-dependent deformation resulting from geothermal fluid injection and extraction. Harrat Al-Madinah, a Cenozoic bimodal alkaline volcanic field in west-central Saudi Arabia, is imaged using shear-velocities obtained from natural ambient seismic noise. To our knowledge, this project is the first analysis of Saudi Arabia structure using ambient noise methods. Surface wave arrivals are extracted from a year's worth of station-pair cross-correlations, which are approximations of the empirical Green's function of the interstation path. We determine group and phase velocity surface wave dispersion maps with a 0.1 decimal degree resolution and resolve a zone of slow surface wave velocity south-east of the city of Medina, which is spatially correlated with the most recent historical eruption (the 1256 CE Medina eruption). Dispersion curves are calculated at each grid-point of the surface-wave velocity maps and inverted to obtain measurements of shear-velocity with depth. The 1D velocity models are then used to produce average shear-velocity models for the volcanic field. A shear-velocity increase ranging from 0.5 to 1.0 km/s, suggesting a layer interface, is detected at approximately 20 km depth and compared to P-wave measurement from a previous refraction study. We compute cross-section profiles by interpolating the inversions into a pseudo-3D model and resolve a zone of slow shear-velocity below the 1256 CE eruption location. These areas are also spatially correlated with low values of Bouguer gravity. We hypothesize that the low shear-velocity and gravity measurements are caused by fluids and fractures created from prior volcanic eruptions. We use the coda of cross-correlations extracted from ambient noise to determine shear-velocity changes at Rotokawa and Ngatamariki, two electricity producing geothermal fields located in the North Island of New Zealand. Stacks of cross correlations between stations prior to the onset of production are compared to cross correlations of moving stacks in time periods of well stimulation and the onset of electricity production using the Moving Window Cross Spectral technique. An increase between 0.05% to 0.1% of shear-velocity is detected at Rotokawa coinciding with an increase of injection. The shear-velocity subsequently decreases by approximately 0.1% when the rate of production surpasses the rate of injection. A similar amplitude shear-velocity increase is detected at Ngatamariki during the beginning of injection. After the initial increase, the shear-velocity at Ngatamariki fluctuates in response to differences in injection and production rates. A straight-ray pseudo-tomography analysis is conducted at the geothermal fields, which reveals that localized positive velocity changes are co-located with injection wells. Lastly, we use ambient noise and active sources at the Ngatamariki geothermal field to determine the structure of the top 200 meters using the Refraction Microtremor technique. We deployed a linear 72-channel array of vertical geophones with ten meter spacing at two locations of the geothermal field and determine average 1D and 2D shear-velocity profiles. We were able to image depths between 57 to 93 meters for 2D profiles and up to 165 meters for 1D profiles. A shear-velocity anomaly was detected across one of the lines that coincided with the inferred location of a fault determined from nearby well logs. This suggests that the method can be used to cheaply and quickly constrain near-surface geology at geothermal fields, where ambient noise is abundant and typical reflection and refraction surveys require large inputs of energy and are hindered by attenuation and scattering in near-surface layers.

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