Seismicity time evolution and 3D/4D seismic tomography of Nesjavellir geothermal field (Iceland)

2020 ◽  
Author(s):  
Ortensia Amoroso ◽  
Ferdinando Napolitano ◽  
Vincenzo Convertito ◽  
Raffaella De Matteis ◽  
Paolo Capuano
Keyword(s):  
Power Plant ◽  
Seismic Tomography ◽  
Geothermal Energy ◽  
Clean Energy ◽  
Velocity Model ◽  
B Value ◽  
Geothermal Field ◽  
Hot Water ◽  
Central Volcano ◽  
4D Seismic

<p>Nesjavellir Geothermal Field is located in the Northern part of the Hengill central volcano in South West Iceland. The Hengill volcanic complex consists of three smaller volcanic systems feeding several geothermal fields with surface manifestations.</p><p>Geothermal energy is currently produced at two power plants, in Nesjavellir and in Hellisheidi. After an exploitation period started in 1947, the construction of Nesjaveillir power plant was completed in 1990. Nowadays it produces geothermal energy of up to 300 MW, which is 1,640 l/sec of hot water and up to 120 MW of electricity.</p><p>Part of the surplus geothermal water from the plant goes into the injection wells and in analogy with the nearby Hellisheidi power plant the re-injection of geothermal gases into basaltic formations is planned. To this aim several tests of fluids deep injection are being conducted to prepare the experimental re-injection of carbon dioxide and hydrogen sulphide.</p><p>In the framework of the H2020-Science4CleanEnergy project, S4CE, a multi-disciplinary project aimed at understanding the underlying physical mechanisms underpinning sub-surface geo-energy operations and to measure, control and mitigate their environmental risks, we investigate the seismicity evolution through the b-value and study the elastic properties of the propagation medium through the 3D/4D seismic tomography.</p><p>The seismicity recorded in the study area is due to different mechanisms. Indeed, while in Hengill the seismicity is originated by volcano-tectonic processes, small earthquake swarms between Hengill and Grensdalur volcano are due to the geothermal activity. Finally, the seismicity in proximity of Hellishedi and Nesjaveiilir power plant appears to be induced by re-injection of waste water from the geothermal production.</p><p>Seismic data are recorded by the Icelandic Meteorological Office (IMO) but also from Iceland GeoSurvey (ÍSOR) and by the COSEISMIQ project. The production data are from the OR energy company.</p><p>We used an iterative linearized delay-time inversion to estimate both the 3D P and S velocity models and earthquake locations. The velocity model is parametrized by trilinear interpolation on a 3D grid. The inversion starts from the 1D velocity model, optimized for the area. Time variations of the medium seismic properties are observed in term of Vp, Vs and Vp/Vs ratio obtained by 4D tomography. The technique consists in applying the 3D tomography at consecutive epochs. Spatial and temporal characteristics of the re-located earthquakes are then analysed by using the ZMAP code to image the b-value in the investigate volume.</p><p>The images obtained for each epoch in terms of b-value, Vp and Vs velocities are then correlated with operational data.</p><p> </p><p>This work has been supported by S4CE ("Science for Clean Energy") project, funded from the European Union’s Horizon 2020 - R&I Framework Programme, under grant agreement No 764810 and by PRIN-2017 MATISSE project funded by Italian Ministry of Education and Research.</p>

3D and 4D seismic imaging of the Nesjavellir geothermal field, Iceland

2021 ◽  
Author(s):  
Ortensia Amoroso ◽  
Ferdinando Napolitano ◽  
Vincenzo Convertito ◽  
Raffaella De Matteis ◽  
Thorbjörg Ágústsdóttir ◽  
...  
Keyword(s):  
Power Plants ◽  
Clean Energy ◽  
B Value ◽  
Geothermal Field ◽  
Parameters Estimation ◽  
Central Volcano ◽  
The European Union ◽  
Small Magnitude ◽  
Geothermal Activity ◽  
4D Seismic

<p>The Nesjavellir geothermal field in the Northeastern part of the Hengill central volcano, South West Iceland, has been exploited since 1990. Geothermal energy is currently produced by Reykjavík Energy (OR) at two power plants around Hengill, at Nesjavellir to the northeast and at Hellisheiði to the southwest. Part of the surplus geothermal water from both plants goes into injection wells, and in analogy with the nearby Hellisheiði power plant the re-injection of geothermal gases into basaltic formations is planned in Nesjavellir. Currently, a test of deep fluid injection is conducted in preparation of the experimental re-injection of carbon dioxide and hydrogen sulphide. The seismicity recorded in the study area is due to volcano-tectonic processes, natural geothermal activity as well as induced seismicity due to production and injection.</p><p>The aim of this work is to seismically image the production area of the Nesjavellir geothermal plant. Where the elastic properties of the propagation medium are investigated through the 3D and 4D seismic tomography and the b-value.</p><p>The available dataset in Nesjavellir consists of 6906 seismic events extracted from ÍSOR’s catalogue, with local magnitude -0.8≤M<sub>L</sub>≤3.8 recorded between October 2016 and June 2020. The earthquakes were relocated in a 1D velocity model optimized for the area. We used tomographic method in which the P- and S-arrival times are simultaneously inverted for earthquakes location and velocity parameters estimation. Re-located earthquakes are further analysed to image the b-value in the investigated volume. Time variations of the seismic properties of the medium are observed in terms of V<sub>P</sub>, Vs and V<sub>P</sub>/Vs ratio obtained from the 4D tomography.</p><p>The results indicate that seismicity in Nesjavellir is mainly concentrated in three different clusters: two are located at shallow depths (1-2 km) while the third reaches down to 6 km depth. The three clusters of earthquakes are striking SW-NE and are all dipping to the west. Both the P- and S-velocity obtained models show lateral variation in E-W direction. A high V<sub>P</sub>/Vs ratio value is observed at shallow depths (due to low Vs values) and high V<sub>P</sub>/V<sub>S</sub> ratio is observed between 3.5 and 6 km depth (due to high V<sub>P</sub> and low Vs values). From the b-value mapping we observe low values (less than 1) at shallow depths and high values where the rate of small magnitude events is considerably higher. For each timestep we observe variations in V<sub>P</sub> and V<sub>S</sub> velocities that seem to be correlated with the fluids involved in field operation.</p><p>This work has been supported by the S4CE ("Science for Clean Energy") project, funded by the European Union’s Horizon 2020 - R&I Framework Programme, under grant agreement No 764810 and by PRIN-2017 MATISSE project, No 20177EPPN2, funded by the Italian Ministry of Education and Research.</p>

scholarly journals A Project To Estimate The Power Capacity Of Geothermal Power Plants Based On The Enthalpy Of Geothermal Fluid And Plant Design

2021 ◽  
Author(s):  
Obumneme Oken
Keyword(s):  
Power Plant ◽  
Geothermal Energy ◽  
Electricity Generation ◽  
Power Plants ◽  
Hot Water ◽  
Power Capacity ◽  
Geothermal Fluid ◽  
Direct Heating ◽  
Single Flash ◽  
Geothermal Power

Nigeria has some surface phenomena that indicate the presence of viable geothermal energy. None of these locations have been explored extensively to determine the feasibility of sustainable geothermal energy development for electricity generation or direct heating. In this context, the present study aims to provide insight into the energy potential of such development based on the enthalpy estimation of geothermal reservoirs. This particular project was conducted to determine the amount of energy that can be gotten from a geothermal reservoir for electricity generation and direct heating based on the estimated enthalpy of the geothermal fluid. The process route chosen for this project is the single-flash geothermal power plant because of the temperature (180℃) and unique property of the geothermal fluid (a mixture of hot water and steam that exists as a liquid under high pressure). The Ikogosi warm spring in Ekiti State, Nigeria was chosen as the site location for this power plant. To support food security efforts in Africa, this project proposes the cascading of a hot water stream from the flash tank to serve direct heat purposes in agriculture for food preservation, before re-injection to the reservoir. The flowrate of the geothermal fluid to the flash separator was chosen as 3125 tonnes/hr. The power output from a single well using a single flash geothermal plant was evaluated to be 11.3 MW*. This result was obtained by applying basic thermodynamic principles, including material balance, energy balance, and enthalpy calculations. This particular project is a prelude to a robust model that will accurately determine the power capacity of geothermal power plants based on the enthalpy of fluid and different plant designs.

An application of induced event interferometry approach at The Geysers Geothermal Field, California, USA

2021 ◽  
Author(s):  
Taghi Shirzad ◽  
Stanisław Lasocki ◽  
Beata Orlecka‐Sikora
Keyword(s):  
Velocity Structure ◽  
General Structure ◽  
Clean Energy ◽  
Velocity Model ◽  
Geothermal Field ◽  
Small Scale ◽  
Low Velocity ◽  
Study Region ◽  
Resultant Velocity ◽  
The Geysers

<p>While the classical tomography approaches, e.g., P-, S-, and/or surface-wave traveltime tomography, provide a general structure of the Earth’s interior, new developments in signal processing of interferometry approaches are needed to obtain a high-resolution velocity structure. If the number of earthquakes is adequate, the virtual seismometer method may be a solution in regions with sparse instrumental coverage. Theoretically, the empirical Green’s functions between a pair of events can be retrieved using earthquake’s cross-correlations. Here, an event interferometry approach was used on a very small scale around Prati-9 and Prati-29 injection wells in the NW of The Geysers Geothermal Field. The study region experienced intense injection-induced seismicity. We selected all events with location uncertainties less than 50 m in a cuboid of the horizontal side ~1 × ~2 km and the vertical edge at depths between 1.0 and 2.0 km. The cuboid was cut into 100m thick layers, and we applied to events from each layer criteria enabling a quasi 2D approach. After calculating the Rayleigh wave group velocity dispersion curves, further processing was performed at a 0.2s period, selected based on the sensitivity kernel criterion. Finally, the relative velocity model of each layer at the depth z was obtained by subtracting the velocity model of the just overlying layer (at the depth z-100m) from the model of this layer. Our resultant velocity model in the study area indicated four low-velocity anomalies. The first one can be linked by the two layers interface topography variation at the top of the cuboid (depth 1000 m). The secondary faults can cause the second low-velocity anomaly. The other two anomalies look to result from fluid injection into Prati-9 and Prati-29 wells. <br>This work was supported under the S4CE: "Science for Clean Energy" project, which has received funding from the European Union’s Horizon 2020 research and innovation program, under grant agreement No 764810.</p>

Structure and activity of the geothermal field of Hvalfjörður (Iceland) from brittle tectonic, geothermal and paleostress analysis

2013 ◽  
Vol 184 (4-5) ◽  
pp. 451-465
Author(s):  
Françoise Bergerat ◽  
Kristjan Sæmundsson ◽  
Loïc Fourel ◽  
Jacques Angelier
Keyword(s):  
Thermal Anomaly ◽  
Hydrothermal Activity ◽  
Geothermal Field ◽  
Hot Water ◽  
Early Pleistocene ◽  
Normal Faults ◽  
Central Volcano ◽  
Fracture System ◽  
The Past ◽  
Geothermal Activity

Abstract This paper presents the results of brittle tectonic, palaeostress inversion, and hydrothermal mineralisation studies of the Hvalfjörður low-temperature geothermal field in Southwest Iceland. This geothermal field (including two pronounced thermal anomalies) is located in the highly altered core area of an extinct and deeply eroded Tertiary central volcano. Most of the geothermal water appears to be conducted by vertical extension fractures. Palaeostress analysis indicates a rather complex stress history, with four major trends of extension involving normal and strike-slip faulting modes as well as dyke injection. Analysis of the data on the relative chronology indicates that these four regimes were closely intricate in time and space. The most important regime is a NW-SE, rift-perpendicular extension related to the oceanic rifting in Iceland. This trend partly controls the past (Pliocene-Early Pleistocene) hydrothermal activity in the Hvalfjörður area; however, an E-W rift-oblique extension also occurred with a N-S trending fracture system including normal faults, dykes and veins that show higher levels of hydrothermal mineralisation. Currently, there is strong hot-water convection, producing a thermal anomaly, in this N-S-trending fracture system. Our study highlights the paleostress evolution and the development of fracture systems in Hvalfjörður, including the past geothermal history; nevertheless the most efficient tool in geothermal prospection in such complex area remains the shallow geothermal survey. It has proved successful in many localities in Early Pleistocene to Miocene rocks where no surface indication of geothermal activity exists.

scholarly journals A Project To Estimate The Power Capacity Of Geothermal Power Plants Based On The Enthalpy Of Geothermal Fluid And Plant Design

2021 ◽  
Author(s):  
Obumneme Oken
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Geothermal Energy ◽  
Power Plants ◽  
Hot Water ◽  
Geothermal Resource ◽  
Power Capacity ◽  
Geothermal Fluid ◽  
Single Flash ◽  
Geothermal Power

Surface phenomena that signal the presence of viable geothermal energy can be found in various locations in Nigeria. None of these locations have been explored extensively to determine the feasibility of sustainable geothermal energy development for electricity generation or direct heating purposes. In this context, the present study aims to provide insight into the energy potential of such development based on the enthalpy estimation of geothermal reservoirs. This particular project was conducted to determine the power output from a geothermal resource given an estimated enthalpy of the geothermal fluid. The process route chosen for this project is the single-flash geothermal power plant because of the temperature (180℃) and unique property of the geothermal fluid (a mixture of hot water and steam that exists as a liquid under high pressure). The Ikogosi warm spring in Ekiti State, Nigeria was chosen as the site location for this power plant. To support food security efforts in Africa, this project proposes the cascading of a hot water stream from the flash tank to serve direct heat purposes in agriculture for food preservation, before re-injection to the reservoir. The flowrate of the geothermal fluid to the flash separator was chosen as 3125 tonnes/hr. The power output from a single well using a single flash geothermal plant was evaluated to be 11.3 MW*. This result was obtained by applying basic thermodynamic principles, including material balance, energy balance, and enthalpy calculations. This particular project is a prelude to a robust model that will accurately determine the power capacity of geothermal power plants based on the enthalpy of geothermal fluid, size of the geothermal resource, and different plant designs. I hope that the knowledge gained from the study will promote best practices in geothermal engineering and emphasize appropriate planning for, and implementation of, geothermal plants.

scholarly journals Making use of geothermal brine in Indonesia: binary demonstration power plant Lahendong/Pangolombian

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Stephanie Frick ◽  
Stefan Kranz ◽  
Gina Kupfermann ◽  
Ali Saadat ◽  
Ernst Huenges
Keyword(s):  
Power Plant ◽  
Water Cycle ◽  
Cooling Water ◽  
Geothermal Field ◽  
Hot Water ◽  
Electrical Grid ◽  
Intermediate Cooling ◽  
Novel Concept ◽  
Flexible Operation ◽  
Operational Data

Abstract This paper describes a novel concept for integrating binary plants at a geothermal site which has been realized within a demonstration project in Indonesia. By using an intermediate hot water and an intermediate cooling water cycle it is possible to integrate a fully-automated binary plant with flexible operation in an existing, predominantly manually operated geothermal field. The paper gives technical component details and describes specific design considerations of the demonstration power plant. Furthermore operational data and experiences are shared. Current binary plant operation is characterized by many starts and stops because of several technical challenges, e.g. electrical grid conditions, as well as by off-design conditions. The proven maximum power capacity until now is approximately 400 kW. By means of a numerical model it is shown that the design capacity of 500 kW can be reached.

scholarly journals Potensi Cadangan Panas Bumi dengan Metoda Volumetrik Pada Sumur Saka-1 Lapangan Panas Bumi “X” Kabupaten Lembata NusaTenggara Timur

2017 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Sari Wulandari Hafsari ◽  
Akhmad Rading
Keyword(s):  
Power Plant ◽  
Geothermal Energy ◽  
Mineral Resources ◽  
Geothermal Field ◽  
Well Drilling ◽  
Reservoir Rocks ◽  
Total Potential ◽  
Geothermal Potential ◽  
Exploration Drilling ◽  
Potential Reserve

<p>Secara geologi Indonesia berada di zona Sabuk Api atau busur vulkanik yang merupakan produk konvergensi berupa subduksi antara lempeng Samudra Hindia-Australia dengan lempeng benua Asia berdasarkan konsep Tektonik lempeng. Potensi Panas bumi Indonesia tercatat sebagai yang terbesar ketiga di dunia dengan potensi cadangan 40%, Direktorat Inventarisasi Sumber Daya Mineral (ESDM) mengidentifikasi 256 daerah panas bumi dengan total potensi mencapai atau sekira 28.617 MW Penggunaan potensi panas bumi Indonesia hingga Tahun 2016 baru mencapai 4% atau sekira 1341 MW sehingga masih perlu ditingkatkan. Target pemerintah tentang kebijakan Energi Nasional terkait penggunaan energi terbarukan sebesar 25% pada tahun 2015, memicu peningkatan kegiatan pencarian dan eksplorasi panas bumi.Penyelidikan Direktorat Inventarisasi ESDM (2006) di Kabupaten Lembata, Nusa Tenggara Timur mencatat tiga lapangan potensi panas bumi yakni : Atadei, Roma dan Adum. Sumber panas bumi umumnya berasosiasi dengan gunungapi menjelang padam maupun masih aktif. Syarat terbentuknya panas bumi adalah adanya sumber panas (magma), batuan reservoir, batuan penudung dan akuifer. Hasil inventarisasi dan eksplorasi. Tulisan ini difokuskan pada perhitungan cadangan yakni energi panas bumi yang kenyataannya dapat diambil dan potensi listrik yang dapat dibangkitkan pada lapangan panas bumi X Kabupaten Lembata, Nusa Tenggara Timur. Tahapan awal dari upaya untuk mengetahui potensi energi panas bumi dimulai dari eksplorasi terencana dan terpadu yang meliputi kegiatan survey geologi, geokimia, geofisika, landaian suhu dan pemboran uji/eksplorasi panas bumi yang diakhiri dengan kegiatan pemboran sumur produksi serta pembangkit power plant untuk listrik jika hasil pemboran uji memberikan gambaran yang positif serta faktor kebutuhan akan energi/listrik.Cadangan energi panas bumi yang kenyataannya dapat diambil di Lapangan panas bumi X adalah 3,94 x 10 11 KJ dan besarnya potensi listrik yang dapat dibangkitkan adalah sebesar 41 Mwe Sehingga Lapangan panas bumi X prospek dan layak untuk dikembangkan sebagai Pembangkit Listrik Tenaga Panas Bumi (PLTP), sehingga kebutuhan listrik masyarakat Kabupaten Lembata sebesar 5 Mwe dapat terpenuhi.</p><p><em>Geologically, Indonesia is in the zone of ring of  Fire or volcanic arc which is a product of convergence in the form of subduction between the Indian-Australian Ocean plate and the Asian continent plate based on the plate tectonic concept. Indonesia's geothermal potential is recorded as the third largest in the world with a potential reserve of 40%, the Directorate of Mineral Resources Inventory (ESDM) identified 256 geothermal areas with a total potential reaching or approximately 28,617 MW The use of Indonesia's geothermal potential until 2016 only reached 4% or approximately 1341 MW so that it still needs to be improved. The government's target of the National Energy policy related to the use of renewable energy by 25% in 2015, triggers an increase in geothermal exploration and exploration activities. </em><em>The investigation of the ESDM Inventory Directorate (2006) in Lembata Regency, East Nusa Tenggara recorded three geothermal potential fields namely: Atadei, Roma and Adum. Geothermal sources are generally associated with near-extinguished volcanoes or are still active. Requirements for geothermal formation are the existence of heat sources (magma), reservoir rocks, capstone and aquifers. Inventory and exploration results. This paper is focused on the calculation of reserves, namely the fact that geothermal energy can be extracted and the potential electricity that can be generated in the geothermal of X field, Lembata Regency, East Nusa Tenggara. The initial stages of the effort to determine the potential for geothermal energy starts from planned and integrated exploration which includes geological, geochemical, geophysical surveying, temperature slope and geothermal test/ exploration drilling which ends with the production well drilling and power plant for electricity if the results test drilling provides a positive picture and energy/electricity demand factors. </em><em>Reserve of geothermal energy which in fact can be taken in the geothermal field X is 3.94 x 1011 KJ and the amount of potential electricity that can be generated is 41 Mwe so that the geothermal of X field prospects and feasible to be developed as a Geothermal Power Plant (PLTP) so that the electricity needs of the Lembata Regency community of 5 MWe can be fulfilled.</em></p>

scholarly journals Wellhead Power Plants Improvement by Introduction of Double Flashing Cycle

2019 ◽  
pp. 24-32
Author(s):  
Thomas Mutero ◽  
Peter Muchiri ◽  
Nicholas Mariita
Keyword(s):  
Power Plant ◽  
Geothermal Energy ◽  
Power Plants ◽  
Low Pressure ◽  
Geothermal Field ◽  
Power Cycle ◽  
Single Flash ◽  
Geothermal Power ◽  
Installed Capacity

Kenya Electricity Generating Company Ltd (KenGen) has harnessed geothermal energy for over thirty seven years at the Olkaria geothermal field. The total installed capacity of geothermal energy in Kenya currently stands at 703.5 MW generated mostly by single flash and binary geothermal power plants. In the 1990s KenGen considered the Wellheads concept in which modular containerized single flash power plants were to be designed, customized and built on a wellpad for optimized well potential; this approach has largely been successful currently having an installed capacity of 83.5 MW and accounting for 15.7% of KenGen's total geothermal installed capacity. This was done to address an inherent deficiency in the construction of conventional geothermal power plants which was identified as the long period taken to put up the power plants. The wells that have been drilled by KenGen and GDC, tested and shut in awaiting the installation of power plants are rated at about 600 MW. The Wellhead power plant cycle is a single flash geothermal power plant; this research intended to improve the current Wellheads power cycle by introducing a second low pressure separator to harness more energy from the wellheads, design a turbine to be driven by the low pressure steam and evaluate an economic justification for introducing the double flashing cycle. A case study was carried out at Wellhead 914 and Wellhead 915. Data collected indicated that the combined mass flow rate of brine from wells in the two wellpads was 240.4 tonne per hour. This brine was saturated at 13.5 bar-a and at a temperature of 193.40C as it exits the high pressure separator for disposal. The optimal pressure of the low pressure separation was designed at 2.5 bar-a, 127.40C and had an ability to generate 3871 kW of electric power. A turbine operating at a steam inlet pressure of 2.5 bar-a, a speed of 6804 rpm and having an exhaust pressure of 0.075 bar-a was designed. The designed turbine had 4 stages of both stationary and moving blades with a maximum rotor disc diameter of 0.62 meters and an output of 4195 kW. The simple payback period for this project was estimated to be 1.9 years with a rate of return on investment of 42.24%. This would also minimize energy wastage by improving efficiency and footprints on the environment arising from the Wellhead power plants.

scholarly journals Geothermal Field Research using Gravity and Electric data in Afyonkarahisar Province of Western Turkey

2021 ◽  
Author(s):  
Ali ELMAS ◽  
Ali Erden BABACAN
Keyword(s):  
Geothermal Energy ◽  
Gravity Data ◽  
Underground Structure ◽  
Field Research ◽  
Geothermal Field ◽  
Hot Water ◽  
Horizontal Gradient ◽  
Western Turkey ◽  
Vertical Electric Sounding ◽  
Holistic Interpretation

Abstract Geothermal is one of the important energy sources because it is renewable energy and does not have any significant damage to the environment. The western Anatolian part of Turkey has a high potential in terms of geothermal energy. The study area, which is thought to have geothermal characteristics, is close to Afyonkarahisar province in Turkey. In this study, gravity data with horizontal gradient magnitude (HGM) and tilt angle map (TAM) techniques, and electric resistivity data with vertical electric sounding (VES) technique are used for the reveal of underground structure and location of hot water regions. Thus, locations with excess geothermal energy can be identified and locations of potential hot water areas can be determined. The possible hot areas are characterized with high density contrast and low resistivity values. According to the calculations made, the depth of the target mass for the geothermal source starts from approximately 300 m and continues up to 1100 m. More reliable and accurate results can be obtained by holistic interpretation of gravity and electrical resistivity methods in a geothermal field.

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