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The Third Sustainable Earth Sciences Conference and Exhibition
- Conference date: October 13-15, 2015
- Location: Celle, Germany
- Published: 13 October 2015
1 - 20 of 48 results
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Geological Labs On Chip - New Tools for Investigating Key Aspects of CO2 Geologi Storage
Authors S. Morais, A. Diouf, C. Lecoutre, D. Bernard, Y. Garrabos and S. MarreSummaryConventional lab scale tools are adequate to access some experimental data related to CO2 geological storage in deep saline aquifers. However, they are lacking from in situ characterization techniques, thus limiting the monitoring and the understanding of the various involved processes. Therefore, new methods are needed to investigate deeply the fundamental mechanisms associated with these four trapping mechanisms. In this context, microfluidics approaches have bring several advantages over conventional experimental means, including fast screening of the parameters, fast heat and mass transfer and the ease of implementation of various characterization techniques. By adapting such approaches to porous media, our team has demonstrated the fabrication and use of the first high pressure / high temperature microreactors, able to withstand harsh conditions up to 20 MPa and 400°C, which were adapted to studies dealing with fluidic within porous media, so called “Geological Labs on Chip – GLoCs”. These tools are at the core of the collaborative project CGSµLab N° ANR-12-SEED-0001 funded by the French national research agency (ANR). We illustrate here after some key results obtained from the use of GLoCs coupled to optical and spectroscopy characterization methods.
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Application of Concepts in Sustainability and Physics to Stimulate the Transition to a Low-carbon Energy Mix
More LessSummarySustainable development is that which meets the needs of the present without compromising the ability of future generations to meet their own needs. In studies of sustainability, the three pillars of sustainability need to work together, namely: (a) environment, (b) social equity, and (c) economics.
In applying these concepts to global energy options, the challenge is to find ways of making low-carbon energy solutions sustainable. Concerning the three main classes of low-carbon energy, last decade has seen a significant growth in the renewables and natural gas sectors; however, CCS has made limited progress. An important route to making CCS a more sustainable option is via CO2-EOR as part of Carbon Capture, Utilization and Storage (CCUS) systems.
To address societal aspects of sustainable development, we need to appreciate that our sustainable future depends on achieving a low-carbon energy mix. The scientific case for the urgent need to protect our atmosphere from the damaging effect of man-made emissions of greenhouse gases is now overwhelming, and is essentially a matter of appreciating the basic principles of physics.
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Towards 4D Joint Inversion for Subsurface Monitoring - Synthetic Study in the Context of the Ketzin CO2 Storage Site
Authors P. Bergmann, M. Jordan, E. Querendez, A. Romdhane, P. Eliasson, F. Huang, F. Zhang, M. Ivandic and C. JuhlinSummaryThe Ketzin project provides an experimental test site for the geological storage of CO2 in Germany. During the CO2 injection period, as well as the ongoing post-injection period, a broad range of geophysical monitoring activities was conducted. In particular time-lapse seismic and electrical resistivity tomography (ERT) data sets have been extensively collected. In order to exploit the complementary imaging characteristics of these co-located data sets, we apply a joint inversion algorithm for combined processing. We use for this purpose an approach which enforces common model structure through spatial parameter gradients. Within this ongoing study, this contribution focuses on the validation of the implemented time-lapse joint inversion algorithm by means of two synthetic models. The second model captures the main features of the geology at the site and includes a hypothetical CO2 distribution. The tests are conducted as a benchmark to study how the joint inversion performs in comparison to the individual inversions and to set up the joint inversion for application to the real data sets from the Ketzin site.
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Process to Generate Hydrogen from Hydrocarbons in Situ - Hydrogen Production, Carbon Capture, Source of Thermal Energ
Authors L. Surguchev, R.S. Berenblyum and A.N. DmitrievskySummaryThe increasing energy demand in the world requires development of environmentally clean alternative energy resources. Hydrogen may become a future fuel in the energy system for a cleaner planet. The development of several types of oil and gas fields have economic limitations. The significant volumes of these already discovered hydrocarbon reserves are:
- Hydrocarbon gas in tight reservoirs,
- Remaining oil in depleted fields,
- Heavy oil and bitumen deposits,
- Coal bed methane.
One of the possible ways to make use of these hard to recover hydrocarbon reserves is to convert them in-situ to a source of clean energy – hydrogen. This process can also enable sequestration of produced CO2 in the reservoir avoiding its release to the atmosphere. Laboratory experiments and simulations have been performed to validate applicability of hydrogen generation from hydrocarbons in the reservoir. In the proposed novel process the reservoir is converted into a ready to produce high pressure hydrogen storage cell. Hydrocarbon processing and transportation stages on the surface are therefore abated.
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Spatial and Temporal Properties of Noise from the Aquistore CCS Pilot Permanent Surface Array
Authors C.E. Birnie, A. Stork, L. Roach, D. Angus and S. RostSummarySynthetic datasets are commonly used to aid interpretation, test hypothesis and as a benchmarking tool for evaluating the robustness of seismic imaging algorithms and defining confidence limits under which an algorithm will perform. Noise within these datasets is often modelled as white and/or Gaussian and therefore does not account for the spatial and temporal variations and trends observed in noise present within field data. This study defines a noise classification scheme that systematically represents these temporal and spatial variations and trends. Noise signals identified at the Aquistore injection site were classified using the scheme defined into the noise categories: stationary, non-stationary and pseudo-non-stationary noise. Future studies will focus on creating a mathematical description of the signals focussing on non-stationary and non-linear aspects with the aim to build this into a synthetic seismic dataset as realistic noise.
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Monitoring Surface Deformation with Satellite InSAR - A Tool for Time Lapse Analysis of UGS
Authors A. Tamburini, S. Del Conte, A. Ferretti and A. RucciSummaryUnderground gas storage in depleted hydrocarbon reservoirs, aquifers or salt caverns can be responsible for surface deformation phenomena. Monitoring surface displacements can support safe reservoir management and provide valuable constraints for modeling the dynamic behavior of a reservoir and help achieve more effective reservoir exploitation with obvious economic benefits. Satellite InSAR represents one of the most valuable and cost-effective techniques, capable of providing high precision and high areal density displacement measurements over long periods of time.
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Volumetric Inference of CO2 at Sleipner Using 4D Seismic Time-shifts
Authors P. Bergmann and A. ChadwickSummaryA method for volumetric estimation of subsurface fluid substitution is presented that relies on the analysis of 4D seismic time-shifts. Since time-shifts cannot resolve for fluid saturation and layer thickness simultaneously without additional constraints, mass estimates are derived from the complete set of possible fluid saturations and layer thicknesses. The method considers velocity-saturation relationships that range from uniform saturation to patchy saturation. Based on a generalized velocity-saturation relationship that is parameterized by the degree of patchiness, explicit upper and lower fluid mass bounds are provided. We show that the inherent ambiguity between fluid saturation and layer thickness has a severe impact on the convergence of these mass bounds. That is, roughly linear velocity-saturation relationships with patchy saturation tend to provide significantly better accuracy in a mass interpretation than the strongly non-linear velocity-saturation relationships associated with homogeneous saturation. The method is validated at the Sleipner storage site, where injected fluid masses are known. Moreover, a linear relationship between 4D time-shifts and injected mass is observed, suggesting that the evolving patterns of fluid saturation and fluid mixing in the CO2 plume at Sleipner have remained roughly constant with time.
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Determining the Limitations to Deep Reservoir Caprock Fracture Characterisation Using AVOA Analysis
Authors L.A.N. Roach, D.A. Angus and D. J. WhiteSummaryThis study uses azimuthal AVO to assess the limitations to detecting and characterising fractures in a 150m thick caprock of a 3200m deep saline reservoir for CO2 storage. Simple and full-waveform synthetic surface reflection seismic data were generated using ATRAK and Wave Unix, respectively, to provide varying levels of signal to noise ratios for the analysis. Nine models with varying noise content, structural complexities and fracture intensity were evaluated. The outcomes of the investigation are that: fracture intensity must be strong to be observable; a layer-stripping mechanism is necessary to reduce the effect of overlaying layers; changes in anisotropy due to changes in fracture intensity can be measured; the direction of anisotropy can be recovered but not its magnitude. The influence of large velocity contrasts is the key uncertainty in the estimation of anisotropy in this geological setting.
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Deformation Prediction in the Otway Basin - A Seismo-mechanical Workflow for Sub-/seismic Fault Detection
Authors C.M. Krawczyk, D.C. Tanner, J. Ziesch, T. Beilecke and A. HenkSummaryThe main challenge of assuring long-term storage integrity and providing sensitive monitoring strategies in the framework of CO2 injection is to unravel the specific potential of communicating systems that occur between reservoir and surface. For this purpose, the joint project PROTECT (PRediction Of deformation To Ensure Carbon Traps) developed a seismo-mechanical workflow to predict and quantify the distribution and the amount of sub-/seismic strain in the proximity of the CO2 reservoir in the Otway Basin.
The sub-seismic space is filled by different, integrated approaches that encompass seismic attributes, retro-deformation, and numerical forward modelling. While the attributes image small lineaments, the retro-deformation shows that, in the seal, ca. 20–30 % strain magnitude on average, with extremes of 80 % along certain lineaments. Locally, the minimum horizontal stress at reservoir is overprinted by faults, as evidenced by numerical modelling.
We calibrated our predictions with shear-wave reflection seismics that evidences areas of sub-seismic faulting. Thus, the workflow reveals possible migration pathways, and as such provides a tool for prediction and adapted time-dependent monitoring for subsurface storage in general.
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Potential Impacts on Groundwater associated with Geological CO2 Storage
Authors S. Fischer, S. Knopf, F. May and D. RebscherSummaryGeological CO2 storage bears potential impacts on groundwater. Potable groundwater resources are legally protected, therefore any potential negative impact caused by CO2 storage has to be considered. Injection of CO2 in a deep saline aquifer will alter the physical and chemical conditions in the reservoir. As a consequence, the in situ fluid is compressed, displaced, and migrates away from the injection site. Furthermore, numerous complexly coupled geochemical reactions occur, e.g. dissolution of alumosilicates. The assessment of site-specific and time-dependent coupled physico-chemical processes is vital to evaluate storage security.
Shallow freshwater aquifers can only be affected by the storage of CO2 in deep saline formations if leakage pathways like faults or abandoned wells facilitate the ascent of CO2 or saline formation water. Leakage cannot be excluded, but potential impacts on the environment should be minimized by site-specific monitoring. Groundwater monitoring involves detecting deviations from baseline or expected conditions and investigating causes of anomalies and verification of leakage. A large number of methods and tools are available from classical quantitative and qualitative groundwater monitoring. In practice, groundwater monitoring faces several challenges however. The primary requirements for safe CO2 storage and groundwater protection are thorough site characterization, conservative risk assessments, and unconditional site selection.
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Assessing the Impact of Deep Brine Injection on Shallow Drinking Water Resources
Authors J.O. Delfs, A. Landwehr and S. BauerSummaryBrine intrusion into drinking water resources induced by energy or carbon storage operations in the deep subsurface are a major concern when employing these storage options. A modeling study of salt leakage from a deep storage formation into a drinking water aquifer is conducted, where brine leakage is induced by injection of salt water. Results show that salt rises due to injection pressures and thermohaline circulation, with permeability being the most sensitive parameter. Salt is rising to the drinking water aquifer by geological layer to layer, so that brine not from the deepest formation but the formation below the aquifer is shifted to the aquifer. Numerical tests show that the model code used can be used on meshes on the order of millions of nodes, thus allowing for a realistic representation of the induced flow and transport processes.
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Cost-efficient Drilling of Deep Geothermal Well
By T. NoevigSummaryThe total cost for deep geothermal boreholes used for heating and electricity is characterized by high investments.
The investments consist of the cost for the geological surveys, the drilling and completion as well as the installations on the surface. As the well cost is making about 70 % of the total investment for geothermal electrical power stations, the greatest potential for cost savings is for drilling the well.
Several factors do have a great influence on the drilling cost for a well.
The borehole design: the cost is increasing disproportionately high with increasing borehole diameter. The development concept for a geothermal project must consider the additional cost for more single rig sites (vertical wells) with higher rig move cost and surface pipeline connections between the sites vs. multiple wells from one cheaper rig site with the risk for highly deviated directional wells.
Longterm drilling contracts including rig sharing with other developers with defined and optimized drilling sequences will reduce transportation cost and dayrates as well as gain from the experience of multiple projects („lessons learnt”).
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Is Geothermal Energy an Alternative for Svalbard?
Authors K. MidttФmme, M. Jochmann, I. Henne, M. Wangen and P.J. ThomasSummaryThere is a drive towards the reduction of climate gas emissions on Svalbard where coal and diesel are currently the main energy sources. A research project lead by Store Norske is investigating the possibilities for geothermal energy utilization on Svalbard as a means to reduce emissions. Fibre optic temperature measurement technology is being tested to provide high quality data from boreholes in permafrost area. Finite element basin model (IFE) and Comsol Multiphysics model (CMR) describing the temperature distribution of the subsurface are being developed. Preliminary results indicate heat flow values above 70 mW/m2. There are also indications of hot spot areas with significantly higher heat flow values.
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Development of Thermal Fractures in Two Dutch Geothermal Doublets
Authors D. Loeve, J.G. Veldkamp, E. Peters and J.D.A.M. van WeesSummaryIn the production well of a low-enthalpy geothermal doublet hot water is pumped from reservoirs at about 50–100 °C. After passing through a heat exchanger, the cold water is re-injected at about 20–35 °C in the injection well into the reservoir, which initially has the same temperature as the produced water. Under some circumstances, this may lead to the initiation of thermal fractures around the injection well, an effect known from water injection in oil wells. This will increase the productivity index (PI), thereby also increasing the efficiency and profitability of the doublet.
Using a simple analytical approach, we studied whether thermal fractures are theoretically expected under typical reservoir and injection conditions. From data at high temporal resolution of two geothermal doublets were studied over a longer period of injection to check if the development of a thermal fracture is observed
The conclusion that can be drawn from the calculations is that cold fractures hardly develop under the assumed conditions. However, the uncertainty on the pressure estimation necessary for the fracture calculation is relatively large. Possible fracture development is very sensitive to value of the minimum horizontal stress and lowering by 10% allows the initiation of fractures in both doublets.
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Induced Seismicity in the Crystalline Basement - What Parameters are Important?
Authors S. Schumacher and M. WuttkeSummaryAlthough induced seismicity in the context of reinjection wells is long known, the geothermal reinjection well Unterhaching Gt2 near Munich, Germany shows a surprising behavior. The injection pressures are quite low (below 10 bar), but seismic events up to magnitude 2.4 have been recorded. The most striking aspect of these seismic events, however, is their location. All of them are located below the open hole section of the borehole and occur within the crystalline basement well below the geothermal reservoir. The necessary hydrological connection between reservoir and basement, which might explain this behavior, is given by a steeply inclined fault zone through which the well passes.
The results of this numerical model show that neither the injection rate nor the injected temperature can explain the observed seismicity and its location. The pore pressure changes caused by the injection rate are much too low (< 1000 Pa) and the induced thermal stresses are confined to the immediate surroundings of the well, so that neither can lead to the induced seismicity within the crystalline basement without the interaction with other parameters which so far have not been considered.
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Assessment of Lower Cretaceous Aquifers Lower Saxony Basin and their Potential for Geothermal Exploitation
By R. PierauSummaryTwo potential sandstones units are present in the Lower Crteaceous in the Lower Saxony Basin. The “Valendis-Sandstone” of Valanginian age could be a primary target for geothermal use. On a regional scale, the sandstone units of the Isterberg Formation of Berriasum age in the central part of the LSB barely meet the minimum requirements for geothermal use. Nevertheless, suitable aquifer conditions may be developed on a local scale.
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Project InSpEE - Rock Mechanical Design for CAES and H2 Storage Caverns & Evaluation of Storage Capacity in NW-Germany
SummaryUnderground storage in salt structures for compressed air or hydrogen are one of the few options for storing renewable energy in grid scale. However, there are only insufficiently substantiated estimates of the total potential.
Therefore the objectives of the InSpEE project are the development and deployment of design principles and basic geological/geotechnical data and of site selection criteria for the establishment of salt caverns as well as the estimation of the renewable energy storage potentials of the salt structures in the North German Basin. Cooperating project partners bringing in their expertise in the areas of salt geology, rock mechanics and planning and construction of salt caverns. Thermo-mechanically based assessment criteria will be applied for the site characterization and an algorithm of the estimation of the possible storage potential will be developed.
Finally, a publicly accessible “Salt information system” will be provided and the estimation storage potential for caverns in NW-Germany shall be addressed. Within this paper the rock mechanical design for CAES and H2 storage in salt caverns under consideration of thermo-mechanical coupled calculations will be presented as well as the methodology and the evaluation of the storage capacity for renewable energies.
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Project InSpEE, Storage Potential for Renewable Energies - Insights into Northern Germany’s Salt Structure Inventory
SummaryWith Germany’s progressive energy revolution and its transition to fluctuating renewable energy sources large scale energy storages will be required. Storage power plants may play an important role for storing excess wind or solar energy converted to compressed air (CAES) or hydrogen. However, large volumes can only be accommodated in the geological subsurface. Because of its thermo-mechanical stability, its low tendency to react chemically with the stored medium and its flexible operation modes, salt caverns represent the preferred storage option.
The focus of the InSpEE project is to provide basic geological and geotechnical data, to compile criteria for the establishment of salt caverns as well as to estimate the total renewable energy storage potential of salt structures in the North German Basin. In this collaborative project, existing expertise in salt geology, rock mechanics and cavern design principles are brought together by the Federal Institute for Geosciences and Natural Resources (BGR), Leibniz University of Hanover – Institute of Geotechnical Engineering/ Department of Underground Construction (IGtH), and KBB Underground Technologies GmbH. The project’s results are integrated into a publicly accessible geo information system called “Salt”. Within this paper we present an overview of salt structures in the North German Basin and their internal compositions.
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Planning and Building of Salt Caverns - A Matter of Sustainability
By B. OttoSummarySalt cavern projects are often managed as pure engineering projects with little involvement of experienced geoscientists. Consequently the post-salt overburden is often regarded as being elastic, isotropic, homogenous and continuous. In fact worldwide salt mining and hydrocarbon exploration experiences proved that post-salt sections of salt domes often are exactly the opposite, heavily faulted; thus at least inelastic and discontinuous. Whereas model simplifications may accelerate project planning ignoring these well-known subsurface facts may have severe costly consequences like for instance shearing of well casings due to fault reactivation or sinkholes at a later stage.
This paper describes one of the rarely published cases where anisotropic 3D pre-stack depth migrated seismic data have been utilized for geological site characterization at an early stage of planning a new salt cavern gas storage facility site in Jemgum (Lower Saxony basin, Germany). Existence of a detailed, spatially precise real 3D subsurface structural model as well enabled an early assessment of potential short, mid and long-term environmental impacts.
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Comparison of Mechanical Energy Storage Concepts Underground - Compressed Air and Pumped Hydro
By F. KaiserSummaryIn this extended abstract the mechanical energy storage concepts that are mainly based on underground facilities are described in detailed. Beside the proven technology of compressed air energy storage (CAES) with underground compressed air caverns the theoretical concept of underground and other new pumped hydro energy storage (PHES) is elucidated. Both CAES and PHES possess a wide range of theoretical variation, such as adiabatic CAES or underground PHES in different mining locations. It is shown that some of these variations are far from realization at the moment or the near future. Furthermore it is demonstrated that when comparing both concepts a new definition of storage efficiency should be applied.
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