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1st Geoscience & Engineering in Energy Transition Conference
- Conference date: November 16-18, 2020
- Location: Strasbourg, France
- Published: 16 November 2020
64 results
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Well Leak and Annular Flow Analysis for a Gas-Well, A Workover Operation in South of Iran
Authors H. Ameri and M. MotahariSummaryThe workover jobs may conduct in a well during or after of completion operation for various reasons. One of the most common problems in the south of Iran is gas leakage and annular pressure increasing in the well. In this paper, the annular flow condition and energy and casing/liner leakage have been investigated by different new technologies such as Well Leak Detector (WLD), Well Annular Flow (WAF) and Ultrasonic Image Tool (USIT) in a well in one of the Iranian southern gas fields. The WLD logs showed no turbulent flow behind of casing. On the other hand, the USIT tests illustrated that laminar flow is not the result of large holes’ existence on the body of completion strings. Two different methods were conducted for better analyzing the WAF tests: Shut-in pass and Bleeding-off pass. All of the WAF sensors have been displayed the same trend for both scenarios in different time periods. The results have demonstrated the precise location of a shale layer and a gas pocket and determined that the leakage is via the liner-casing joint. Finally, casing/liner punching, squeeze cementing and tying back the liner was suggested and applied in the well as an optimum workover operation.
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Flow Simulation and History Matching of a High Enthalpy Geothermal Reservoir: The Larderello Case Study (Italy)
Authors P. De Montleau, F. Felici, M. Casini and M. CeiSummaryThe Larderello-Travale field (Tuscany, Italy) is the oldest historical areas of geothermal exploration and exploitation in the world. Two reservoirs have been progressively investigated and exploited and the current case study focuses on the deepest fractured reservoir in the southwestern area of the field. It is characterized by temperatures of 250–350°C with an initial static pressure of around 70 bar. The modeled area is historically managed by 64 producers and 12 injectors.
The study consisted in a 3D static and dynamic modeling and particular attention was paid to natural fractures distribution within the reservoir. The history matching was performed on the natural state and production history which started in the nineties.
The aim of the study is to give a better understanding of the production mechanism of a naturally fractured geothermal field by mean of fracture characterization and distribution. This calls for a detailed description of well productivity and interference between closed wells and groups of wells.
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Multiphase Compositional Well Flow Modelling: The Case of Injecting in Low Pressure Reservoirs
Authors V. Leontidis and M. GainvilleSummaryA steady-state compositional flow model has been developed for simulating the injection of condensed steam together with non-condensable gases (NCGs). All fluids are originated from a high enthalpy subsurface source, and after the recuperation of their energy in a geothermal power plant they must be reinjected back into the earth for controlling the emissions of greenhouse and toxic gases. For high content of NCGs in the initial geothermal fluid and reinjection of the totality of the fluids, the dissolution of the gas into the liquid phase is partial and a two-phase mixture must be injected. Targeting a low pressure (depleted) reservoir for the injection can result in a liquid column inside the well which is far for the surface in a depth of several hundreds of meters. The model considers a prototype well completion which overcomes these restrictions by injecting separately the water and the NCGs, and by mixing the two phases in a certain depth while ensuring the downward flow of the mixture.
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Utilizing the Geology to Your Advantage; Innovative Shallow Geothermal Energy in Crystalline Rocks
More LessSummaryShallow geothermal energy is an increasingly important source for heating and cooling of buildings in Scandinavia. Norway’s geology bears some challenges relating to shallow geothermal energy. The dominating geology is crystalline bedrock, which does not allow for the development of e.g. ATES. LEAT is a concept that is developed by Ruden Energy and based on the utilization of the fracture network in fractured crystalline rocks and the naturally occurring groundwater, in an open-loop well system. Instead of trying to avoid fracture systems and groundwater flow, LEAT enables the utilization of these features. The benefit of LEAT is that this concept requires a significantly lower number of wells to deliver the same amount of heating and cooling to a building or infrastructure when compared to more traditional closed well systems. There is a potential of creating an energy system with the same energy output with just 10 % of the number of wells in a traditional closed well system.
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Corrosion Inhibitor Evaluation Using Autoclave Electrochemical Measurements in Geothermal Brine
Authors T. Schott, M. Bolmont, A. Rouand and F. LiautaudSummaryTo protect a geothermal plant of the Upper Rhine Graben, the performance of commercially available corrosion inhibitors was evaluated in laboratory. Experiments, and in particular electrochemical measurements, were successfully conducted at 170°C, 22 bar, in autoclave to measure steel corrosion rates in utilization conditions, and to reproduce the scale deposits observed on-site. Among the inhibitor products the least toxic for aquatic life, one was able to reduce the steel corrosion rate in geothermal brine from 80 to 30 µm/year at 80°C, and from 450 to 180 µm/year at 170°C.
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Modeling of CO2 Solubility in Aqueous NaCl and Na2SO4 Solutions up to 473.15K and 20MPa
Authors P. Felipe Dos Santos, L. André, M. Ducousso, F. Contamine and P. CézacSummaryThe study of the phase equilibria of CO2 in aqueous solutions containing electrolytes is extremely relevant for several areas such as environment, oil and water production, or geothermal energy. With regard to the environment, CO2 capture and storage (CCS) in deep saline aquifers has been widely studied, as a strong potential for mitigating the global imbalance linked to greenhouse gas emissions. CO2 storage in deep aquifers is seen as the most promising geological storage techniques due to the large quantity and spreading of the reservoirs worldwide.
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Experimental CO2 Solubility in Nacl-Cacl2 Brines At 333.15 and 453.15 K Up to 40 Mpa
Authors J. Lara Cruz, F. Contamine and P. CézacSummaryAs part of the global efforts for renewable energies development, CO₂ solubility measurements were provided for the geothermal industry. Solubility is obtained at high pressures (6–40 MPa), in aqueous phases reproducing the exploited geothermal resources, through NaCl and CaCl₂ synthetic brines (1.2 mol NaCl/kg H₂O and 0.2 mol CaCl₂/kg H₂O), at 333.15 and 453.15 K. This work is encouraged by the lack of literature measurements on CO₂ solubility at these experimental conditions. Both mixed-salts and single-salt brines are analysed for the production of original results. A new stirred reactor, with variable volume, was conceived to maintain gas-liquid equilibria, while solubility measurements were performed by titration. The experimental methods were validated with measures in pure water, at 333.15 K, as well as in NaCl and CaCl₂ single-salt brines (1 mol.kg H₂O), at 323.15 K. Then, twenty original measures were produced with their uncertainty, and compared to Phreeqc (Pitzer.dat) calculation results. The measurements highlight that CO₂ solubility decreases when the aqueous phase salinity increases. Finally, a discussion is proposed to determine if this salting-out effect is influenced mostly by the NaCl or the CaCl₂, when observed in the mixed-salts brines at 333.15 K.
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Characterization of Crustal Fault Zones as Geothermal Reservoirs: A Multidisciplinary Approach
Authors H. Duwiquet, L. Guillou-Frottier, L. Arbaret, T. Guillon, M. Heap and M. BellangerSummaryAs potential geothermal reservoirs, Crustal Fault Zones are still largely unexplored and unexploited (e.g. South Erzebirge deep fault zone, Germany (Achtziger-Zupančič, 2017), GraVisual Basic Expresserg, Sweden (Juhlin and Sandstedt 1989 , Lund and Zoback 1999 )). A multi-disciplinary approach has made it possible to estimate the position of the 150 °C isotherm at 2.5 km depth at the Pontgibaud Crustal Fault Zone (French Massif Central), highlighting its geothermal potential ( Duwiquet et al., 2019 ). Although consistent with field data, this estimate did not take the 3D distribution of permeability, the 3D geometry of fault networks, and the poroelastic effects on fluid flow, and the intensity and depth of temperature anomalies into account. With more measurements, observations, and 3D modeling based on thermo-hydro-mechanical (THM) coupling, this study proposes to better characterize the geothermal reservoir potential of the Pontgibaud Crustal Fault Zone.
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Laboratory-Based Investigation into the Fluid Flow Properties of Natural and 3D-Printed Rough Fractures
Authors T. Phillips, N.D. Forbes Inskip, O. Esegbue, G. Borisochev, T. Bultreys, V. Cnudde, K. Bisdom, N. Kampman and A. BuschSummaryLow-permeability geological seals may be compromised by the occurrence of fluid-conductive fault and fracture systems, which can potentially transmit fluids away from the storage reservoir. We performed a systematic laboratory-based investigation into the effect of surface roughness on the fluid flow properties of both natural rock and 3D-printed fractures. The natural rock fractures span a range of lithologies and modes of creation. The synthetic fractures were numerically generated through accounting for complex matching properties and anisotropies within the defining properties of a fracture surface. A multipronged experimental approach was undertaken, comprising digital optical microscopy for roughness quantification, single-phase (core flooding) experiments for permeability evolution with effective stress, and X-ray micro-computed tomography (μ-CT) performed on 3D-printed fractures to investigate aperture field evolution during fracture closure. Results from this study provide further insights into the physical transport properties of fractures as a function of lithology, angle to bedding and surface roughness distribution. This work is used to directly inform caprock leakage models for a joint industry research project, which aims to generate guidelines for determining the risk of CO₂ leakage along faults and fractures in low-permeability caprocks.
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The Geothermal Energy Buffer: A Promising Carbon Free Solution for Bulk Energy Storage
By A. JeannouSummaryEnergy transition and, on a larger scale, climate change is a paradoxical problem for a geologist. He is probably very familiar with earth’s natural resources availability and also knowledgeable about past marine transgressions effects. Therefore, his knowledge allows him to anticipate the effects of the rapid fossil carbon destocking in the atmosphere. This carbon destocking will be carried out in approximatively 200 years; it is so quick that today, alarming atmospheric CO2 levels have been generated.
However the perplexing problem, geoscientists can and should take action to help our fellow human beings. First, by constantly reminding the necessity to recycle as much as possible finite natural resources, and second, by offering clean and sustainable energy solutions, for us and future generations.
Our proposal is the Geothermal Energy Buffer project. It’s a clean and definitely sustainable bulk energy storage solution based on: thermal storage, energy generation and management of a phase change hydrocarbon, the LPG. Through its performance, dispatchability and power, this innovation has the potential to be comparable to hydropower. This solution is rapidly deployable worldwide in spent oil fields and in many sealed equivalent geological structures. It has the ambition to become a game changer in the electricity market.
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Understanding Fault and Fracture Networks to De-Risk Geological Leakage from Subsurface Storage Sites
Authors R.E. Rizzo, H. Fazeli, C. Maier, R. March, D. Egya, F. Doster, A. Kubeyev, N. Kampman, K. Bisdom, J. Snippe, K. Senger, P. Betlem, T. Phillips, N. Forbes Inskip, O. Esegbue and A. BuschSummaryTo verify successful long-term CO2 storage, it is critical to improve our understanding of leakage along natural faults and fractures within the primary caprock. In the proximity of a fault zone, interactions between multiple fracture sets can create complex networks which can play a fundamental role in fluid transport properties within the rock mass. Being able to fully characterise fault and fracture networks, in terms of fracture density, connectivity, aperture size and stress regime, can allow us to more accurately identify, analyse and model the bulk properties (e.g. transport, strength, anisotropy) and, therefore sealing behaviour, of faulted and fractured geological storage sites. Here, we present an integrated workflow which combines laboratory measurements of single fracture permeability with outcrop-scale analysis of fault and fracture networks occurring in reservoir/caprock sections. These data are then used to develop a hydromechanical model to upscale laboratory tests to network-scale and potentially to reservoir-scale, verified against in-situ fault permeability data, where available.
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Chemical Reactions in Subsurface Storage Rocks - First Results from Reactive Fluid Flow Experiments
Authors B. Busch, A. Okamoto and C. HilgersSummaryFaults and fractures are important fluid pathways in subsurface energy reservoirs. Especially in geothermal energy production, hydrocarbon production, and energy storage in the deep subsurface, fractures can enhance reservoir quality and production- or storage potential. In subsurface reservoirs however, mineral precipitations often reduce available fracture apertures, and thus fracture porosity and permeability. The present study is performed on a homogeneous, massive marine Sandstone (Bentheimer Sandstone from Gildehaus Quarry, Lower Saxony, Germany, Lower Cretaceous) and a heterogeneous, laminated fluvial sandstones (grès vosgien from Cleebourg, Alsace, France, Lower Triassic). Hydrothermal flow-through experiments are performed at 420 °C and 30 MPa for 72 hours to compare resulting precipitated cement textures on fracture analog surfaces.
The experiments reveal a heterogeneous development of syntaxial overgrowth cements. Homogeneous sandstone, composed of similar grain sizes and quartz grains, show a homogeneous formation of overgrowths. Heterogeneous sandstones, composed of laminae with different grain sizes and variable detrital grain compositions, show smaller overgrowths on finer grained laminae when compared to coarser grained laminae.
The sedimentary texture might thus be an additional factor to consider when assessing mineral precipitations in fractures and their influence on subsurface fluid flow.
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Hydrogen Reactivity with (1) a Well Cement - PHREEQC Geochemical Thermodynamics Calculations
Authors N. Jacquemet, P. Chiquet and A. GraulsSummaryTEREGA has been using an aquifer of southwestern France to store natural gas since 1957. The storage and the surface facilities are connected by cement-completed wells. The PHREEQC geochemical thermodynamics calculations presented herein aim at evaluating if hydrogen reactivity with a class G oil-well cement would have an impact on its porosity, in a context of hydrogen co-storage in the aquifer. The reductive dissolutions of the model cement minerals ettringite and hematite were driven by the sulphate and ferric iron reductions by hydrogen. The so-produced sulphides and ferrous iron precipitated as iron sulphide and oxide minerals. Nevertheless these dissolution-precipitation reactions did not affected significantly the cement porosity, as the involved minerals constitute a minor part of the material. The strong hypothesis of this study resides in the fact that the redox reactions reached the chemical thermodynamics equilibrium. But it is known that their extent is kineticallylimited; they need to be catalysed through e.g. the metabolism of hydrogenotrophic microbes. Our study could be thus improved by including such microbial kinetical equations, as well as kinetics for mineral dissolution/precipitation reactions. Also, we could consider reactive transport simulations in which the diffusive transport of hydrogen within cement is taken into account.
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CO2 Handling in Binary Geothermal Systems – a Modelling Approach for Bruchsal, Germany
Authors D. Siefert, M. Kondek, T. Koelbel and J. KolbSummaryImplementation of the CO2-solubility model of Duan et al. (2006) into a simulation tool for the Bruchsal power plant yields results that indicate single-phase flow at 22 bar, at the production temperature of 124 °C, 130 g/L total dissolved solids and at a CO2-content of 0.3 wt.%. This, however, contradicts the observation in Bruchsal. The simulation was adjusted to 22 bar and 124 °C, yielding a CO2-content of 0.85 wt.%. The simulation is validated against gas breakout pressure measurements, which indicate that single-phase flow was not reached until 31.7 bar (operating conditions 22 bar). Using this pressure as a minimum value, the minimum CO2-content at single-phase conditions is estimated at 0.86 wt.%, which is in accordance with the results from the modified simulation tool. The general applicability of the new simulation tool has to be validated at other sites, before it can be implemented into a holistic power plant model. The successful validation at Bruchsal indicates that the new simulation tool and its implementation into holistic models is a promising tool for predicting NGC behaviour early in the development of geothermal power plants already in the exploration stage.
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Characterisation of Deep Hydrothermal Fluids Circulation in the Upper Rhine Graben (France) with Electromagnetic Methods
Authors S. Neeb, V. Maurer, M. Darnet, F. Bretaudeau, P. Wawrzyniak, C. Glaas, J. Girard, G. Marquis and A. GenterSummaryIn the present paper we present a new combination of 3D Controlled-Source Electromagnetics (CSEM) and Magnetotellurics (MT) adapted to image electrical resistivity of deep granitic fractured reservoirs. This method will be applied in the Upper Rhine Graben to locate and describe accurately the geothermal resource in order to reduce the risk of future Enhanced Geothermal System (EGS) projects planned in this area. Electrical resistivity logs data from Soultz-sous-Forêts and Rittershoffen (Alsace, France) geothermal wells will be used to design an optimal survey, since knowledge of resistivity variation in the sedimentary cover is required to properly image deep fluid circulation with high accuracy. As a first validation step, a 2D field trial run in July 2019 near the geothermal power plants from Soultz-sous-Forêts and Rittershoffen successfully characterized the subsurface targets. The main goal of this study will be a large-scale 3D CSEM/MT acquisition campaign, planned on October 2020 in Northern Alsace, in a context of an actual exploration program.
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Multi-Scale Faults/Fractures Network Characterization of the Saarbrucken-Merlebach Anticline (Saar-Lorraine Coal Basin) for Geothermal Exploration
Authors M. Mombo Mouketo, Y. Geraud, M. Diraison and C. BossennecSummaryFaults and fractures are mechanical discontinuities that develop at all scales due to brittle deformation of rocks. Because of their complex geological history, they can be sealing or conductive to fluids. Moreover, this geological complexity results in very heterogeneous fracture systems both in orientation and spatial distribution. Description for the total range of size is difficult to predict from subsurface data or well data. Surface analogues are used to overcome this difficulty. Here, the focus is made on the folds/faults/fractures of the Westphalian interval of the Saar-Lorraine coal basin. This interval is the richest in coal seams and is folded.
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Full Wave Inversion of OVSP Seismic Data for Faults Delineation and Characterization in Granite Context
Authors Y. Abdelfettah, C. Barnes, E. Dalmais, V. Maurer and A. GenterSummaryWe have studied the application of the full-wave inversion method (FWI) to offset vertical seismic profiles (OVSP) in order to detect, delineate and characterize the heterogeneities and the faults in the deep granite geothermal reservoir. We consider the context of Soultz-sous-Forêts geothermal site. The main goal of this study is to evaluate the application of a method already used in the oil&gas industry to geothermal purpose and to assess its capability for the specific goal of fault imaging. After having tuned the FWI to adapt to the specific target of faults, we have studied the impact of the acquisition geometry on the estimated parameter fields, namely, the Pwave and S-wave velocity model and the density model. We have shown that for noise free synthetic data and for fault orthogonal to the propagation plane, the fault signal in the data is sufficient to obtain good inversion results. However, several sources are required to better constrain the inverse problem. We have also studied the sensibility of the FWI for different fault thickness, dip and position as the scattered field depends strongly on these parameters. This study has to be continued by using 3D FWI to assess the fault azimuth effect.
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Implementing the Cascade Use of Geothermal Energy in Agriculture and Assessment of Usage with MCDM Tool
More LessSummaryBased on the outdoor air temperatures at the location of the Lunjovec-Kutnjak geothermal field, the utilization of geothermal energy for heating the greenhouses was dimensioned through two thermo-technical systems. The first system involved the direct use of geothermal energy, and the second system involved the direct use of geothermal energy and the use of heat pumps after direct use. Such a cascading hybrid system through direct use and heat pumps represent the possibility of exploiting a larger temperature range and generating greater revenues. After sizing the system, MCDM analysis was performed according to the methodology presented in ( Ilak et al., 2018 ; Raos et al., 2019 ), together with the proposed weight parameters determined for agriculture. The results of the analysis showed a higher final grade of the cascade hybrid system for agricultural purposes where the parameters of installed capacity and levelized cost of heating (LCOH) had the greatest impact and geological parameters did not have a significant impact since they are the same in both proposed systems.
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Carbon Storage Potential in the Los Angeles Basin
Authors S. Cook, K. Batbayar and Z. PrintzSummaryPermanent carbon storage relies on detailed subsurface characterization and subsequent dynamic modeling to predict plume and pressure geometries. In this study, Schlumberger evaluated carbon storage feasibility in the Los Angeles Basin using proven geomodelling and simulation workflows in Petrel and Eclipse. Specific geologic criteria must be present in the subsurface to achieve permanent storage. A saline sand formation with appropriate injectivity properties exists, is thick enough to ensure sufficient storage capacity, and is deep enough to store CO2 in a super critical state (800 m). An overlying shale formation must exist regionally to confine injected CO2. Once these criteria were met, leakage pathways and other subsurface risks were considered. For the purpose of this study a geocellular facies model was created from public and raster log well data to calculate storage capacity and identify five prospective storage site locations. Evaluation criteria such as fault leakage and reactivation, distance to subsurface operations, and reservoir storage potential were used to rank prospective locations. After identifying the most feasible proposed location, Eclipse dynamic modeling was performed using an injection rate of 1 million tons CO2/year over 20 years plus 50 years post injection to predict carbon plume migration and stabilization.
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Delivering the CO2 Storage Resource Catalogue
Authors S. Thibeau, J. Canal Vila, M. Martins and J. RitterSummaryJuly 1st, 2020, the Oil and Gas Climate Initiative (OGCI) launched the CO2 Storage Resource Catalogue. The Catalogue aims to become the global repository for all future storage resource assessments, supporting the growth of a safe and commercially viable CCUS industry. It will do this by bolstering investors’ understanding of commercial development and maturity of published CO2 storage resources, thereby leading to increased investor confidence. It is based on the SRMS, A CO2 storage classification system established by the SPE in 2017.
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Basin Modeling for Shifting the Petroleum System Models to the Needs of the Energy Transition
Authors M. Cacas-Stentz, A. Reinert-Brüch, J. Frey, D. Colombo, J. Berthelon, T. Cornu and C. GoutSummaryBasin modeling is a technology for simulating the geologic processes involved in the development of sedimentary basins. It was developed for the purpose of Oil & Gas exploration to predict the location and nature of hydrocarbon traps and to identify overpressure risk before drilling.
With a few additional development efforts, the range of basin modeling applications can be enlarged. In the present paper, we show that coupling basin modeling with an existing mechanical simulation code makes it possible to accurately model the spatial distribution of geomechanical stresses and natural fracturing at regional scale, which are a valuable information in the frame of geothermal or CO2 storage site screening or production modeling. The coupled simulation is applied to the case study of the Neuquèn basin, Argentina, where it appears that tectonic stress significantly controls overpressure development and natural fracturing. This illustrates the potential use of basin modelling simulations for making decision or assessing and selecting optimal location for CO2 sequestration or geothermal exploitation at the basin scale.
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Building New Business in the Energy Transition Using Upstream Capabilities and Assets
Authors H. Coppes, E. Vermolen and E. Hoogerduijn StratingSummaryMany of the developed technical capabilities in Upstream can be directly transferred into developing new business opportunities in geothermal energy, E-hubs, CCS and energy storage. Also, Upstream assets are well suited to be re-deployed for generation of renewable energy. The outlook of scaling up projects provides an opportunity for business improvement through standardization and life-cycle development planning, areas where Shell has proven capabilities.
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Hydrogen Reactivity with (2) an Aquifer - PHREEQC Geochemical Thermodynamics Calculations
Authors N. Jacquemet, P. Chiquet and A. GraulsSummaryTEREGA has been using for 60 years an aquifer in southwestern France to store natural gas. This would be a potential host for hydrogen co-storage. In this context, we evaluated through PHREEQC geochemical thermodynamics calculations the possible rock-fluid interactions and their consequences on the reservoir porosity. The following reactions were predicted: methanogenesis (conversion of carbonates to methane), accompanied by an alkalinisation of the water; ferric iron; sulphate; disulphide; and nitrogen reductions by hydrogen. These reactions led to the reductive dissolutions of the reservoir rock minerals calcite, goethite, barite and pyrite. Dissolution of kaolinite was also predicted, due to the alkalinisation of the water. The released elements/compounds precipitated as iron sulphide and zeolite minerals while baryum and sulphides accumulated in the water. The mineral dissolution-precipitation reactions did not affected significantly the reservoir porosity. These results need to be put in perspective regarding the maximizing assumptions of constant hydrogen fugacity and thermodynamic equilibrium reaching. Our study could be improved by: (i) including kinetics for hydrogenotrophic microbial metabolic as well as for mineral dissolution-precipitation reactions; (ii) considering the advective-dispersive-diffusive transport of hydrogen within aquifer. Our modelling results will be compared to the outcomes of the laboratory tests of the R&D project RINGS.
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Energy Transition, Strategies and Competencies: Outcomes from an AI Decision Support System
By L. LevatoSummaryThe project ZEST (Zero Emission - Skills for Transition) uses an AI to investigate the changing needs of the energy sector in terms of competences to face the challenges of the energy transition. The results indicate that the Oil and Gas sector is generally adapting to this challenge in the continuity of its core capabilities, in particular by realigning its portfolio. Data Science and Machine Learning are relevant to foster agility, confirming what is widely communicated in the media. Soft-skills which favour innovation, such as searching alternatives, changing paradigms, adaptability, anticipating situations, versatility, future orientation, are perceived as central to addressing the energy transition. We are preparing a second run of the AI to explore which additional players in the energy transition, beside the O&G and the mining industry, will most likely require the expertise of geoscientists.
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Above Zone Aquifer Pressure Survey as Part of CCS Intelligent Monitoring System
Authors F. Aloueke, M. Jazayeri Noushabadi, V. Jaffrezic and A. BrissetSummaryAbove zone, Monitoring, pressure transient analysis, leakage
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Well Placement Optimization Based on Pressure Gradient Distribution; Applicable to CO2 Sequestration
Authors H. Derijani, R.D. Haynes and L.A. JamesSummaryIn well location optimization, the appropriate selection of initial guess for the optimization algorithms can reduce the required number of simulation runs. In this research, the idea of well location optimization based on pressure gradient distribution in the reservoir for CO2 injection is presented. Targets are those with low absolute pressure gradients leading to the areas minimally influenced by the existing injection wells.
The pressure profile of a steady-state case is applied to define the objective function based on the pressure gradient and superposition principle. The numerical active set method is implemented for the optimization algorithm as it can include the effect of multiple wells and linear boundaries. In a simple reservoir of fixed properties, this corresponds to the optimum well location for injection or production, whereas in a reservoir with variable properties, the result is an initial guess for the optimization process. The optimization algorithm is addressed for two scenarios including two and four CO2 injection wells.
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Integrating AI with CMMS Maintenance Module to Reduce Offshore Operational Breakdown
Authors D.K. Pandey and D. PandeySummaryBASSNET is a Computerized Maintenance Management System (CMMS) which is utilized by FPSO to track the records for preservation and troubleshooting jobs performed on equipment. BASSNET not only provides the detail of work orders, but also helps management in understanding the equipment’s working behavior and based on those performances, decisions are made to improve the integrity and life of an asset. Despite of several advantages, the software has few limitations due to which machine downtime still exists. AI (Artificial Intelligence) Database Module such as PREDIX, Hybrid Data Platform (HDP), etc. can be used in order to overcome the limitations of BASSNET. In this technical paper, operational shortcomings of BASSNET is highlighted and accordingly a blueprint is proposed to integrate the Breakdown Report (BDR) in the CMMS with the help of AI Database Module. This integration would not only enhance the scheduling of preventive maintenance but also initiates the predictive maintenance based on past breakdown history
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Net Zero Teesside: Subsurface Evaluation of Endurance
Authors F. Sutherland, L. Duffy, D. Ashby, P. Legrand, G. Jones and E. JudeSummaryNet Zero Teesside is planned to be the first decarbonised industrial cluster in the UK by 2030. CO2 will be captured at a combined cycle gas turbine (CCGT) power station and other industries in Teesside and the CO2 compressed and piped out to the Endurance structure in the Southern North Sea. The reservoir for storing the CO2 is the Triassic Bunter Sandstone Fm.
To move the project forward (planned to enter FEED in late 2020) the subsurface team have undertaken a number of workstreams to assess and assure the capacity, containment and injectivity of Endurance for CO2 storage. In this paper we look at some of this work and its impact on the project. This includes the reprocessing and interpretation of seismic data, integrated sedimentological description for facies to populate the geocellular model, structural analysis to assess overburden faulting and sea integrity, and an understanding of the rock properties of the aquifer for pressure dissipation during CO2 injection.
The new work has fed into a geocellular model to assess a large range of downside scenarios to ensure the project is robust, and this model has been taken through dynamic simulation to investigate development scenarios.
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The Potential of High-Temperature Storage Systems in Depleted Oil Reservoirs in the Upper Rhine Graben
Authors K.R. Stricker, J. Grimmer, R. Egert, J. Bremer, M. Gholami Korzani, E. Schill and T. KohlSummaryHT-ATES (high-temperature aquifer thermal energy storage) systems represent a future technology to shift large amounts of excess heat from summer to winter using reservoirs in the deep underground. Among others, depleted hydrocarbon-bearing reservoir formations may constitute favorable storage conditions for HT-ATES. This study characterizes these reservoirs in the Upper Rhine Graben (URG) and quantifies their heat storage potential numerically. Assuming a doublet system with semi-annual injection and production cycles, injection at 140 °C in a reservoir with an ambient temperature of 70 °C leads to an annual storage capacity of up to 12 GWh and significant recovery efficiencies increasing up to 82 % after ten years of operation. Our sensitivity analysis of operational conditions identifies reservoir conditions (e.g. permeability or thickness) and the drilling configuration (horizontal/vertical) as the most influencing parameters. With about 90 % of the investigated reservoirs in the URG potentially transferable into HT-ATES systems, our analyses reveal a large storage potential of these oil reservoirs.
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Making ESG Considerations Relevant in Mineral Exploration Projects – Lessons Learned from INFACT Project
Authors M. Komac, C. MacCallum and J. RussilSummaryThe importance and value of considering Environmental, Social and Governance (ESG) factors at the start of the exploration process can be demonstrated by numerous projects across Europe, the ongoing antimining sentiment as well as arbitration cases. INFACT’s research in deciding what methods to use where and when during the different phases of mineral exploration has involved determination and consideration of a range of technological and ESG factors.
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Risks and Challenges of the Transition to an Integrated Geothermal Concept for the Göttingen University Campus
Authors B. Leiss, D. Romanov and B. WagnerSummaryThis study presents the main strategic risks and challenges to be faced during the prospective transition from the existing fossil fuel-based energy system to an integrated „Enhanced Geothermal Systems” -concept, which includes deep, medium, and shallow geothermal energy, for district heating and cooling of the Göttingen university campus (demo site of the EU-HORIZON2020-project MEET). Such an innovative integrated concept aims for lowering the financial risks and maximizing decarbonisation effects. The geological and technical preconditions of the demo site are analyzed, and a basic conceptual scheme is suggested. To overcome the challenges of the implementation of such a complex system, an intensive cooperation between all stakeholders, coherent planning and financing, and a modular, step-by-step approach is a prerequisite.
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Transitioning from Oil and Gas to Geothermal: A Geoscience Perspective
Authors J. Hardman, R. Bolton, E. Drumm, R. Crossley, C. Olivares, E. MacInnes and R. JarvisSummaryThere are over 300 geothermal plants operating in 35 countries. The majority of the power plants occur in geologically complex high-temperature volcanic areas and limited well success rates in these settings limits commercial returns. Future geothermal drilling will turn increasingly to sedimentary basins. In this context, there are some key similarities between the skills, understanding and data used for the exploration and exploitation of hydrocarbons and that of geothermal energy. Insights into the geoscientific challenges faced in drilling sedimentary basins will enhance our ability to evaluate and develop geothermal resources in a manner that minimises subsurface risk. This paper aims to outline the different phases of a geothermal exploration and development campaign, highlighting areas of overlap between the geothermal industry and knowledge and data from the petroleum industry. By utilising the potential synergies between the petroleum and geothermal industries, the energy industry will be well positioned to transfer from oil and gas to geothermal.
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GEORISK: Developing Geothermal Projects By Mitigating Risks
Authors P. Dumas and C. SerranoSummaryGeothermal project development has several risky components, the most important one being the resource risk. Until the first borehole has been drilled into the geothermal reservoir, developers cannot be sure about the exact parameters (temperature and flow rate) of the planned geothermal electricity or h&c project.
Risk insurance Funds for the geological risk already exist in some European countries (France, Germany, Iceland, The Netherlands, Denmark, Flanders in Belgium and Switzerland). However, such Funds have been not existing in several countries prospective for geothermal deployment (including eg. Greece, Hungary, Poland).
The establishment of such risk mitigation scheme all over the world to cover the exploration phase and the first drilling (test) is key for a large development of deep geothermal. But it appears clear that a risk mitigation scheme must be designed, especially the involvement of private financers, according to the market maturity of the sector in each country and region.
The GEORISK project, which started in October 2018 for 30 months, aims at establishing such risk insurance schemes all over Europe and in some key target third countries to cover the resource and the technical risks.
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GEOENVI: Tackling the Environmental Concerns for Deploying Geothermal Energy in Europe
Authors P. Dumas and V. MazzagattiSummaryThe advantages of using geothermal for power production and H&C are not widely known. Recently, deep geothermal energy production in some regions is confronted with a negative perception, particularly in terms of environmental performance, which could seriously hamper its market uptake. Thus, environmental impact assessment is a prerequisite to the deployment of the deep geothermal resources. The concept of Life Cycle Assessment (LCA) allows analysis and comparison of the environmental impacts of different energy production technologies over their life cycle stages – from extraction of raw materials to production, transport, use and endof-life.
GEOENVI project, kicked-off in November 2018 for 30 months, aims at engaging with both decision-makers and geothermal market actors, to adopt recommendations on environmental regulations and to promote the Life Cycle Assessment (LCA) methodology implementation by geothermal stakeholders.
The project aims at proposing recommendations on harmonised European environmental regulations to the decision-makers, at elaborating simplified LCA models to assess environmental impacts and finally at communicating properly on environmental concerns.
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Seismic Velocity Characterization and Modelling for Synergetic Utilisation of CO2 Storage Coupled with Geothermal Energy Extraction
Authors M. Janssen, J. Russel, A. Barnhoorn, D. Draganov, K. Wolf and S. DurucanSummaryWhile deep geothermal energy is seen as a zero-emission renewable energy source, bulk of the geothermal energy plants do emit carbon dioxide (CO2) as part of the produced steam. In the current ACT Consortium funded project SUCCEED, researchers are investigating the potential for injecting produced and captured CO2 into the reservoir with the aim of enhancing geothermal production as well as permanently storing CO2 at the Kizildere (Turkey) and Hellisheidi (Iceland) geothermal fields. The re-injection of CO2 will be monitored at both sites using a novel seismic monitoring system. Prior to conducting active seismic surveys, we are performing a combined experimental and modelling study in order to: i) select the proper acquisition configuration for both sites, and ii) help the interpretation of field data to be recorded. This research presents a well-controlled laboratory study on the relationship between axial and radial stress and seismic velocities. Our first experimental results show that the rate of velocity increase, as function of increasing stress, is largest at low absolute stresses. This most probably reflects the closing of microcracks at low stress values, resulting in increased velocities. The results obtained in the laboratory, that reveal seismic velocities as function of stress (i.e. depth) for each of the different lithologies, are used as an input for modelling seismic reflections at Kizildere (Turkey) and Hellisheidi (Iceland). For both sites, we perform simulations where the source-receiver configurations and the type of pore-fluid (brine or CO2) are varied. Our first simulations show that changing the pore-fluid from brine to CO2 yields an overall lowering of the bulk density and seismic velocity of the reservoir, the latter resulting in an increased acoustic impedance contrast. The modelling results will be used for designing an optimal active seismic survey at both project sites for monitoring the CO2 injection.
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Modeling of Transient Multiphase Flow in a CO2 Injection Well with the Wellbore-Reservoir Coupled Simulator T2Well-ECO2M
Authors K. Strpic, A. Battistelli, S. Bonduà, V. Bortolotti, P. Macini and L. PanSummaryThis paper presents preliminary results of a new T2Well version, coupled with modified ECO2M equation of state, able to simulate three-phase flow in the wellbore with the coexistence of liquid and gaseous CO2, with the final aim to be able to detect possible operational problems caused by phase changes during transient flow periods.
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Environmental Impacts of Geothermal, Natural Gas and Biomass Used for Heat Generation at a Starch Plant
Authors M. Douziech, G. Ravier, P. Perez-Lopez and I. BlancSummaryIn the framework of the GEOENVI H2020 project a LCA model of the Rittershoffen geothermal heat plant was performed in compliance with the methodological guidelines developped as part of this research project The application of the new LCA model provides an updated estimate of greenhouse gas emissions as well as additional results for several environmental indicators. These environmental impacts for geothermal heat generation are also compared to the heat generated by natural gas and biomass.
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4D Seismic Modelling Applied to CO2 Leak Detection: Sensitivity Analysis - Part A
Authors C. Le Magoarou, E. Schissele-Rebel and P. ThoreSummaryWhen injecting CO2 in a reservoir interval, one of the main risk to monitor is the possibility of a leak into an upper reservoir interval through a fault or a legacy well. This paper presents a 1D sensitivity study on the key parameters accounting for the leak detectability using time-lapse seismic: the ambient noise and the repeatability of the acquisition device used. Dealing with thin layers of CO2 also raises new concerns on the reliability of the amplitude, thickness and position of the detected anomaly because of the tuning phenomena. The tuning thickness is a function of the frequency of the wavelength used in the modelling process as it is equal to a fourth of the dominant frequency.
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Limiting Sand Production in Unconsolidated Aquifers: Implications for Low-Enthalpy Geothermal Well Development
Authors N. Buik and M. De KruijfSummaryThe geothermal energy sector is rapidly developing in the Netherlands. Low-enthalpy direct use geothermal wells are typically developed in aquifers at depths of 1,800–3,000 m, the same reservoirs targeted for hydrocarbon exploration. Alternative shallower targets include unconsolidated aquifers within the North Sea Supergroup, with producible water at temperatures of 20 - 50 °C. To maximize heat extraction from these aquifers high flow rates are needed. Conversely, the well design must inhibit the mobilization of formation grains. In the Netherlands well design criteria for aquifer thermal energy storage (ATES) systems (typically < 200 m depth) consist of a maximum flow velocity on the borehole wall, which is independent of depth. For wells in deeper aquifers (300 – 1,500 m), the in situ stress as a function of depth is not incorporated in the design. The Drucker-Prager criterion can be used to determine shear failure at formation depth, so that a maximum allowable flow rate can be calculated. Empirically derived relations from the literature are presented to determine input parameters for the DruckerPrager criterion if lab measurements are absent. A comparison of the different well design criteria demonstrates that in situ stresses need to be incorporated for maximum allowable flow rate estimations.
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4D Seismic Modelling Applied to CO2 Leak Detection : 3D Case Study - Part B
Authors C. Le Magoarou, E. Schissele-Rebel, M. Boisson, S. Bakthiari and M. Jazayeri NoushabadiSummaryWhen injecting CO2 in a reservoir interval, one of the main risk to monitor is the possibility of a leak into an upper reservoir interval through a fault or a legacy well. This study presents a 3D seismic modelling of a CO2 plume in the main reservoir and the associated leak computed using a fully coupled reservoir-geomechanics simulation. The modelling is performed using a 30Hz and a 60Hz wavelet and filters are applied to mimic the resulting detectable seismic signal using different acquisition devices. The leak geometry and physical characteristics are also studied to create guidelines on the key parameters accounting for its detectability.
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Hydrogen Storage in Depleted Gas Fields – First Insights from Conceptual Reservoir Modelling
Authors T. Huijskes and W. EikelenboomSummaryH₂ storage in gas fields is a relatively underexplored topic of research. This study gives first insights on the reservoir dynamics, which are different from underground natural gas storage reservoirs, due to the different fluid properties of hydrogen and the risk of methane breakthrough (or any other gas present in the reservoir). Based on this, a new definition of WV:CV is proposed. Which reservoir characteristics are (more) relevant for the WV:CV (than others) is explored in part 1 of this study.
To get a generic idea on future application of hydrogen storage in gas reservoirs, first insights on future hydrogen storage demand are used to define a set of requirements for a hydrogen storage reservoir (or: a set of reservoirs), which includes the period and frequency of send-in and send-out. This was used for part 2 of this study, which explores the longer term effects in reservoir dynamics by simulating multiple cycles of pre-defined periods based on the required storage demand.
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Full-Scale HT-ATES Tests Demonstrate that Current Guidelines Considerably Overestimate Sand Production Risks in Deeper Unconsolidated Aquifers
Authors B. Drijver, P. Oerlemans and W. BosSummaryThe majority of the heat demand in Europe is supplied by the burning of fossil fuels. To reduce CO2-emissions in the heating sector, sustainable alternatives for heat production are increasingly applied (geothermal, solar and residual heat). However, the heat availability of such sources does typically not match with the heat demand in time. Storage of surplus heat can solve this mismatch, thereby optimizing the use of sustainable heat sources. High Temperature (>30ºC) Aquifer Thermal Energy Storage (HT-ATES) is considered a promising large-scale heat storage technique. Within the GEOTHERMICA-HEATSTORE research project, a demonstration HT-ATES project was realized in the Netherlands, in an unconsolidated aquifer at 380 m depth. For Dutch ATES systems, the ‘NVOE-guideline’ is used to determine the maximum flow velocity in the aquifer around the well, to limit sand production. This limits the flow rate of the well. The HT-ATES well test results demonstrate that, at this depth, considerably higher flow velocities (factor 3.8) can be applied in unconsolidated aquifers than NVOEguidelines suggest. Based on the field results, a depth-correction factor for the NVOE-guideline is proposed. These findings may have a major positive impact on the potential of HT-ATES (and other) wells in unconsolidated aquifers at larger depths (>150m).
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3D MT and Gravity Joint Inversion Modeling of Graben-Hosted High Temperature Geothermal Fields
Authors W. Soyer, R. Mackie, S. Hallinan, F. Miorelli and H. SiagianSummaryFollowing from our recent work on joint inversion of MT, gravity, and MEQ data from the Darajat field ( Soyer et al, 2018 ), here we illustrate the pros and cons of quantitative integration of MT and gravity data through 3D joint inversion modeling, including major fault structures. We use both a 3D synthetic example as well as field survey data from the Sorik Marapi geothermal field, Sumatra. While MT results were largely similar for both single and joint domain inversions, gravity inversions – with inherently weaker depth sensitivity than MT – benefited significantly from the integration, in both cooperative and joint workflows. Additionally, by including faults as inversion regularization discontinuities, the graben boundary locations – well constrained by the gravity data – is represented faithfully. Through integrated inversion modeling of multiple geophysical data types over geothermal fields, and allowing sharp boundary structure, we achieve a multi-property 3D model that consistently explains the observations of each geophysical dataset, and should be more geologically reliable than stand-alone efforts.
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Quantitative Conformance Assessment in CO2 Storage Reservoirs under Geological Uncertainties Using Convolutional Neural Network Classifiers
Authors E. Barros and B. BoullengerSummaryResponsible use of geological reservoirs for storage purposes requires that operators demonstrate that their assets can be managed safely or, in other words, in conformance with the intended plan and targets. Smart monitoring plans provide sufficient evidence of the reservoir behavior to improve the understanding of the system and support decision making regarding subsequent development, operational and monitoring activities. In previous work we introduced a model-based workflow to objectively quantify the usefulness of monitoring within the context of conformance verification in CO2 storage under geological uncertainties, to support the design of effective monitoring strategies. Now we investigate the use of convolutional neural networks to render conformance classification more practical and swift within the workflow. The approach was applied to a case study based on a real storage aquifer and showed to be suitable for conformance classification based on time-series pressure measurements and 2D time-lapse images of the CO2 plume. The results obtained indicated that both types of data can, in time, provide sufficient evidence for accurately inferring the chances of future migration of CO2 to undesired areas of the reservoir. These promising results confirm the suitability of machine learning techniques to further improve workflows for quantitative conformance assessment under uncertainties.
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Training, Dialogue and Public Engagement At an Early Stage of Mineral Exploration – INFACT Project Experience
Authors M. Komac, L. Benighouse and T. MikloviczSummaryContribution presents the various and extensive outreach and dissemination activities to stakeholders/target groups that were performed within the INFACT Horizon 2020 project.
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Characterization of Discontinuities in Potential Geothermal Reservoirs of Vieux Habitants Area (Guadeloupe, French West Indies)
Authors B.A. LEDÉSERT, R.L. HÉBERT, Y. AZZIMANI and G. BEAUCHAMPSSummaryGeotref program aims at developing geothermal resources in andesitic rocks of Basse Terre of Guadeloupe (French West Indies) at an about 2km depth. No drill-hole being available, a surface natural analogous system was found in a 2Ma old area of Basse Terre representing an exhumed 2km-deep portion of crust. In order to better know the morphology of deep reservoirs, an analysis of discontinuity networks was performed. The methods used in the field and in the lab are multiscale analysis of scan lines, mozaiks of pictures, fractal analysis, intensity and density of fracture measurement, analysis of schistosity. The main results are: the regional-scale fractures are recorded at the outcrop scale ; discontinuities that carried hydrothermal fluids are interconnected vertical fractures and horizontal schistosity with a similar filling of newly-formed hydrothermal clay minerals. All of these evidences indicate that fluid flow in such environments occurs not only thanks to vertical fractures as described at Bouillante, a few kilometers to the north, but also via horizontal discontinuities such as schistosity and likely lava flow or debris flow boundaries. Fluid flow occurs from millimetric to metric scale (and likely even more) in the three dimensions of space.
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CROWDTHERMAL: Empower Citizens and Local Communities to Participate in the Development of Geothermal Projects
Authors I. Fernandez and T. MikloviczSummaryIn this presentation we’d like to introduce you to a pioneering EU-funded project launched in 2019 called CROWDTHERMAL, formed of a consortium of 10 partners from across Europe and drawn from the world of finance, social and geosciences and from across Europe. Its aim is to examine how best to engage, enthuse and equip local communities to drive the uptake of geothermal energy as a viable heat, power and, possibly, critical minerals source that contributes to their well-being as well as the greater continental aims of the Green Deal and energy transition.
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A Hosted Cloud Platform for Collaborative Management of Integrated Geothermal Subsurface Models and Data
Authors J. Elliott, B. Poux, B. Williams, J. O’Brien, R. Podgorney and C. BaxterSummaryThere are many issues with integrated sub-surface geothermal studies; different disciplines are involved, alternative models and scenarios need to be investigated, new (sometimes conflicting) data are collected and interpreted to update the models, multiple organisations and people working in different locations and time zones may also be involved. When data and models are housed in siloed file structures and on individual computers finding the most up to date version of the information required can be cumbersome and often leads to repetition of work or the wrong version of information being used. The paper describes a cloud-based solution that tackles this challenge, including powerful visualisation and collaboration whilst providing the “one version of the truth”. A case study from the FORGE project, sponsored by the US Department of Energy’s Geothermal Technology Office encompass all of these issues. This highlights the challenge of how multi-disciplinary teams can work together in a coherent way on a day to day basis and at the same time be able to present their work to inform a wider audience. We present a workflow and a software system for providing an integrated environment that supports multiple users and disciplines, model management, audit trails, visualisation and collaboration.
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Performance Assessment of Underground Gas Storage for Potential Hydrogen Storage in the Netherlands
Authors J. Juez-Larré, C. Goncalves Machado and R. GroenenbergSummaryMany energy transition studies mention hydrogen as one of the candidates to replace natural gas in the Netherlands. However, the future production of hydrogen will primarily depend on the variability of hydrogen production from renewables (wind, solar) and/or the import of natural gas or hydrogen. In order to reduce the dependency on the fluctuating production from renewables and import, large amounts of hydrogen may need to be stored to balance supply and demand.
While there is plenty of experience on underground (natural) gas storage (UGS), knowledge on underground hydrogen storage (UHS) is still limited and mostly related to salt caverns. In this study, we performed a nodal analysis to quantify and compare the differences in performances between UHS and UGS. For that we quantify the inflow and outflow performances of the reservoir-wellbore system, storage capacity, and operational limitations using an in-house Gas Storage Performance tool (GaSP-tool). As a case study we used three UGS facilities in the Netherlands. This allows us to validate our predictions on UGS, and investigate the factors determining the performance of UHS. The results from this study will help to assess the potential for redevelopment of UGS, or natural gas reservoirs, into UHS as energy buffers.
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Toward Quantitative CO2 Storage Monitoring: Estimation of Pore Pressure and Saturation from Geophysical Inputs
Authors B. Dupuy and A. RomdhaneSummaryWe demonstrate how pore pressure and saturation are inter-dependent and affecting the geophysical observables (seismic, EM, gravimetry). We run two rock physics inversion tests where we estimate pore pressure and saturation from seismic attributes.
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Characterization of Sulfide Scales Deposited At Soultz-Sous-Forêts (France) in a Prototype Small Heat Exchanger
Authors B.A. Ledesert, J. Mouchot, R.L. Hébert, C. Bosia and X. SengelenSummaryThe Soultz-sous-Forêts (Soultz in the following) geothermal power plant currently reinjects brine at 70°C. In the framework of the H2020 MEET project, a prototype small heat exchanger (SHEX) has been tested at Soultz during three months in order to enhance energy production. Six metallurgies were tested during the lowering of brine temperature from 70°C to 40°C. The scales deposited in the SHEX have been characterized using ICP-MS and SEM-EDS. This test shows that the composition of scales is rather independent of the metallurgy and of the temperature. In the presence of corrosion and scaling inhibitors, scales are mainly composed of As- and Sb-bearing galena with sometimes minor Cu. This scale composition is identical to that currently encountered at Soultz when reinjecting the brine around 70°C. No new type of deposition was triggered by decreasing down to 40°C, but lowering of temperature tends to induce an increase of scale thickness. This characterization of scales is a key feature for the optimization of the heat exchanger: the thinner the scales, the better the heat exchange and a good knowledge of scales allows a better formulation of scale inhibitors, and potentially a better identification of the cleaning process to be implemented.
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How Lithofacies Types in a Reservoir Analog Facilitate Reservoir Quality Assessment - Buntsandstein Case Study S-Germany
Authors C. Schmidt, B. Busch and C. HilgersSummaryLithofacies types present a means to characterize subsurface facies from description of the sedimentological inventory. While sedimentary structures and grain size can be assessed in core and outcrop, dimensions and lateral extension are best observed in outcrops on the 10 to 100m-scale. Thus analogs are needed to map lithofacies types in 2D to 3D.
In our study we assess lithofacies types in a Lower Buntsandstein outcrop of the marginal facies in Southern Germany. The outcrop consists of wavy- and cross-bedded, subarkosic sandstones. Lithofacies types were cropping out in 3D and could be characterized macroscopically and with regard to mineral assemblage allowing to unravel the paragenetic sequence. Petrographic results were linked with porosity and permeability measured in plugs representing three spatial directions. Those revealed that flow directions play a subordinate role in the studied deposit, whereas lithofacies types coincide with markedly different petrophysical properties. The wavybedded lithofacies exhibited permeability ranges of 10-3 to 100 mD while the cross-bedded lithofacies type hosts permeabilities of 10-1 to 102 mD.
Our case study evidences how lithofacies type mapping in outcrop analogs offers an opportunity to construct and assign buildings blocks for fluid flow models that outdo permeability assessments from wireline logs and core descriptions.
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Detailed Geological Reservoir Characterisation Using an Integrated Analysis of Borehole Image Logs
Authors C. Vahle, Z. Veselovsky and B. RuehlickeSummaryFor the geological characterisation of subsurface borehole image logs provide an excellent data source. Using specialised software for QC and a tailored processing chain high-resolution images of the borehole circumference are obtained, which are able to resolve sub-cm scale features. The image observations are upscaled and used for calibration of seismic scale features within the larger field area. Demonstrated by examples from hydrocarbon and geothermal exploration wells the structural analysis re-constructs palaeo-horizontal and any changes due to faulting and tilting during and after deposition of the stratigraphic sequence. Faults and fractures are characterised in great detail, including a quantification of fracture density and porosity, and are interpreted with respect to their influence on hydraulic conductivity. A correlation of fracture density with elastic properties allows the connection with seismic derived parameters, hence the field wide scale. The sedimentological analysis evaluates transport directions and unravels the depositional environment from features visible in the borehole image. The vuggy porosity is quantified using a semi-automatic work flow. Image facies stacking patterns are used for calibration of seismic-scale sequence boundaries interpreted in terms of possible reservoirs. The stress field direction and stress magnitudes are inverted from breakout and drilling-induced fracturing. The stress tensor data is then used in order to optimise mud weight and well path for future wells, as well as for evaluation of fracture permeability. Borehole image logs therefore represent a prime tool for characterisation of oil and gas, geothermal or CO2 storage reservoirs.
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A Brief History of a Disruptive Nodal Technology
Authors A. Ourabah, M. Popham, C. Einchcomb and N. GoujonSummarySeismic systems have traditionally used cables to transmit the data from the sensors to a central system. Lately, nodal systems have been introduced, where the data is recorded internally in a battery powered sensor node. Removing the cables can make operations vastly more efficient, however the large size and weight of the current nodes, and their cost, have limited the operational benefits and made it difficult to increase the channel count. We present a new nodal system that overcome these issues. It was originally developed to make high density seismic possible and affordable for the oil and gas industry, and has been successfully tested in different environments.
The system has now been adapted to the needs of the geothermal industry and is currently being tested on surveys in Europe.
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CHPM2030 Project - Combined Heat, Power and Metal Extraction from Ultra-Deep Ore Bodies
Authors É. Hartai, T. Madarász and T. MikloviczSummaryThe European economy is heavily dependent upon energy and mineral supply for industry and society. Therefore, key challenges are: lowering the costs and the environmental impact of energy production, and decreasing the dependence on imported strategic raw materials. Responding to these challenges, the EU funded CHPM2030 project was set up to develop a novel technology, which combines deep geothermal energy production with metals extraction from the geothermal fluid in a single interlinked process (Combined Heat Power and Metals – CHPM). In order to improve the economics of deep geothermal energy development, the project has investigated possible technologies for mobilising metals from metal-bearing geological formations with geothermal potential at a depth of 3 to 4 km, and potentially even deeper, and recovering metals from the geothermal fluid at surface. Thanks to the research by the CHPM2030 Team, the co-production of energy and metals might become possible and may be optimised according to market demands in the future.
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Performance Influences of a Deep High Temperature Fractured Geothermal System
Authors R. Van Der Kooij, Y. Wang, A. Daniilidis and D. VoskovSummaryTo assess the influences of various parameters in ultra deep (>4km), high temperature, fractured geothermal systems, the system’s NPV was evaluated as these parameters were varied. The examined fracture network had multiple fractures leading between the wells in a single doublet. The tested input parameters concern rock matrix parameters (permeability, porosity, thermal conductivity and heat capacity), apertures in the fracture network and cold-water injection rates. After simulation of flow, the resulting data has been used for the calculation of NPV, which provided an indication for the performance.
Larger values for matrix parameters and higher fracture apertures amplified each other’s positive effect they had on the NPV of the system, as they both prevented bottlenecked flow of injected water from injector to producer wells and kept the system lifetime longer by allowing injected water more time to absorb heat before reaching the production well.
An optimum exists when selecting injection rate with regards to system NPV. Lower injection rates lead to lower energy production, while higher injection rates lead to shorter lifetimes. A balanced injection rate lead to a maximum NPV.
More investigation into optimization of injection rate over system lifetime will prove valuable for maximizing performance.
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Thermodynamic Pathways of CO2 Storage in Depleted Gas Reservoirs
Authors P. Kowollik, S. Khamnaeva, F. Vodopic, M. Kleczar and H. AlkanSummaryThe use of depleted hydrocarbon reservoirs for CO2 storage can be preferred as it offers financial and technical advantages in comparison to deep saline aquifers. Considering higher available space in unit pore volume depleted gas reservoirs (DGR) are particularly good candidates. However, the engineering of DGRs is not straight forward due to challenging thermodynamics in the injection and reservoir sides.
We investigate the topic to understand the engineering design questions using data from a Dutch offshore depleted gas field to be applied for CO2 storage. We use a commercial simulator and various realistic scenarios; our aim is to numerically emphasize and discuss various aspects of the challenge to widen the understanding and the use of related tools.
First, we speculate on the potential thermodynamic pathways of CO2 travelling from the emitter to the deep reservoir based on realistic injection scenarios. In a second step we study the cases modelling the gas reservoir using radial geometry to allow a more precise description of near wellbore region. Results of various thermodynamic pathways are presented in the paper and the results are discussed in terms of flow assurance during the lifetime of CO2 injection process.
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Uncertainty Quantification of a Real Low-Enthalpy Geothermal Reservoir
More LessSummaryThe efficient development of a geothermal field can be largely affected by the inherent geological and physical uncertainties. Besides, the uncertain operational and economic parameters can also impact the profit of a project. Systematic uncertainty quantification involving these parameters helps to determine the probability of concerning outputs. In this study, a low-enthalpy geothermal reservoir with strong heterogeneity, located in the West Netherlands Basin, is selected as the research area.
Detailed geological model is constructed based on various static data including seismic and log interpretation. However, significant uncertainties still exist in definition of the model parameters, mainly reservoir permeability and porosity. Besides, the fluid properties have not been sampled in this field and can vary in the range between brackish to highly saline water. Also, the heat price and operational investment fluctuate with time and add up to uncertainty. Taking all interested parameters into consideration, the Monte Carlo method is utilized to select specific input data set. The forward simulations are powered by the GPU version of Delft Advance Research Terra Simulator (DARTS), which provides efficient simulation capabilities for geothermal applications. Through this investigation, a wide range of production temperature has been observed due to the uncertainty of the input parameters.
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An Integrated CCS Approach Combining CO2 Injection EOR and Underground CO2 Storage
Authors S. Stamataki, E. Koffa, I. Dimitrellou and V. GaganisSummaryCO2 Capture and Storage is a mainstream topic due to the increasing greenhouse gas issue and the need for green energy policies. Additionally, the oil price crash asks for improved recovery factors from brown oil reservoirs by means of EOR techniques such as miscible CO2 injection. Modern trends require that CCS is combined to EOR in unified reservoir management projects aiming at capturing CO2 from point sources and injecting it to achieve miscible flow conditions. The CO2 flood is followed by production stop and additional CO2 injection so as to maximize gas storage.
Designing such projects is not a trivial task as possible overestimation of the oil reservoir capability to store CO2 might have an enormous economic impact both to the power plant operator and the reservoir operator. A road map is needed to minimize the risks while maximizing the CCS approach benefit.
In this work we discuss the steps followed in the detailed design and optimization of such integrated projects involving two-fold CO2 storage. The strategy is applied to a moderate size oil field in the Kavala basin in Northern Greece. The procedure utilized, the storage results achieved and the anticipated economic impact of the venture are presented.
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Temperature Monitoring of Injection Tests in the Litoměřice Geothermal Borehole
Authors T. Fischer, J. Šafanda, P. Dědeček, J. Holeček, L. Rukavičková, J. Řihošek, J. Vlček and F. CornetSummaryThe pilot 2.1 km deep geothermal borehole LT-1 in Litoměřice (NW part of Bohemian Massif) was a subject of injection tests aimed at assessing the reservoir hydraulic characteristics of the rock massif. In the first stage carried out in January 2020, 25 cubic meters of water were injected to the open hole section of the borehole. Seismic monitoring using a dense array of stations did not indicate any induced seismicity. The flow in the hole was monitored using the distributed temperature sensing (DTS) methodology, which allowed for clear identification of permeable structures. We show the first results of data processing, numerical simulation and interpretation of the hydraulic and DTS monitoring data and discuss the prospects of further development of this pilot EGS test site.
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Evaluation of Potential Applicability of Depleted Gas-Condensate Fields for CO2 Sequestration and EOR: Synthetic Case Study
Authors O. Burachok, M.L. Nistor, G. Sosio, O. Kondrat and S. MatkivskyiSummaryTraditionally, deep saline aquifers are considered and evaluated for long term geological storage of CO2 due to relatively high CO2 solubility in water. In the oil industry, also, CO2 is used is as one of the injection agents to displace oil and enhance its recovery. The utilization of depleted gas fields for CO2 storage, however, is considered to be a more expensive option compared to oil field, since the enhanced recovery of gas with CO2 is not effective. For this reason, our study considers the potential use of CO2 EOR (enhanced oil recovery) in depleted gascondensate fields.
This potential is evaluated by performing numerical simulations for typical-size gas-condensate reservoirs with and without active aquifers, in order to estimate both storage efficiency and additional oil recovery from condensed C5+ hydrocarbon fractions, that otherwise will be never recovered and lost in the reservoir. Obtained results indicate significant potential for CO2 storage and additional condensate recovery from the typical gas-condensate field of Eastern Ukraine.
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Natural Gas Storage - Viability as Hydratesb
By D. PandeySummaryGas Hydrates or Clathrate Hydrates are crystalline solids, its unit cell consists of a gas molecule (Methane in context of Natural Gases) surrounded by water molecules and the crystalline structure is stabilized by the presence of gas molecule within the cage of water molecules around it. Experiments have proved that Methane Hydrates remained stable and did not decompose when stored at temperatures in the range of -15°C to -5°C, at atmospheric pressure whereas LNG needs to be stored at -162°C. Also, one litre of fully saturated Methane Clathrate contains around 169 litres of methane gas at 0°C and 1 atm, thus requires less volume for storage. In laboratories Methane Clathrates have been successfully produced in stirred vessels at pressure from 2 to 6 MPa and temperatures ranging from 0 to 20°C, thus making it feasible for conversion of Natural Gas into Hydrates and storing them, which can be later used during peak demands. Better stability and reduction of storage cost makes Clathrate Hydrates a compelling alternative to LNG and operating costs can be reduced. This technical paper aims to provide an insight into LNG alternative Hydrates and its feasibility.
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Characterization of the Basement/Cover Unconformity Based on Saint Pierre Bois Quarry Observations (Rhine Graben, France)
Authors C. Dezayes, C. Lerouge and P. LachSummaryAccording to the literature, deep geothermal energy reserves are associated with naturally fractured/faulted reservoirs in various geological contexts. In the Upper Rhine graben, several deep geothermal plant exploit the transition zone between crystalline basement and sedimentary cover as a reservoir for heat and power. However, the complexity of this zone makes characterization of its heterogeneities a great challenge to the development of geothermal resources.
At the Saint Pierre Bois quarry, on the western graben border, the granitic crystalline basement is overlain by arkoses. Fracture orientation measurements and rock sampling were conducted on all accessible quarry benches, providing rich datasets for both the granite and the arkose.
The fracture dataset in granite can be interpreted as a large evolved Riedel N80°E fault zone. The core zone is the most highly weathered-fractured zone in the quarry. The two major fracture sets (E-W and N30°E) identified in the damage zone represent shear fracture in the R-direction and P’ fracture, respectively. The E-W structures were the pathways of deep hot fluid circulation at the cover/basement transition. Most of the smallest cataclastic structures associated with this stage are sealed, whereas the highest porosities are present at the margins of large breccia corridors.
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Insitu Hydrogen Production from Hydrocarbon Reservoirs - What Are the Key Challenges and Prospects?
Authors P. Ikpeka, J. Ugwu, P. Russell and G. PillaiSummaryIn-situ production of hydrogen from hydrocarbon reservoirs presents an innovative and cost-effective solution to produce hydrogen from fossil fuel sources. It involves the injection of oxygen-enriched air into the reservoir to initiate combustion within the reservoir. As the temperature of the reservoir increases above 500 - 700oC, thermochemical reactions take place to produce hydrogen: aquathermolysis, thermal cracking, water-gas shift reaction, and coke gasification. In this study, the strength, weaknesses, opportunities, and threats to this technology are discussed. The weaknesses identified presents important research direction for this technology.
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