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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
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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Porous Media Hydrogen Storage - Dimensioning and Induced Hydraulic, Thermal and Chemical Effect
Authors W.T. Pfeiffer, L. Dedong, B. Wang and S. BauerSummaryUnderground storage of hydrogen in porous media could be an option for storing large amounts of energy over time periods of days to months in order to dampen the fluctuating power generation from renewable sources like wind or solar power. In this study, possible dimensions of such a hydrogen storage, operating parameters as well as induced effects on the subsurface are investigated using numerical scenario simulations. The H2 storage is simulated using a heterogeneous sandstone layer in an anticlinal structure located in northern Germany. The parametrization of the storage formation is based on a local facies model. The simulated storage is capable of delivering about 200000 GJ of energy over a period of one week, a typical period of reduced wind power generation. The induced hydraulic effects of the storage do not show a strong dependence on the formation heterogeneity and are restricted to less than one bar overpressure for distances larger than 4.5 km. Chemical effects are limited to the zone taken up by the dissolved gas components in the formation water, which is approximated by the distribution of the gas phase. This zone strongly depends on formation heterogeneity and extents up to 3 km laterally.
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Pressure Response of Compressed Air Energy Storage in Porous Formations - Design of Underground Storage Operation
Authors B. Wang, W.T. Pfeiffer and S. BauerSummaryCompressed air energy storage (CAES) in porous formations is considered as one option of storing renewable energy in the subsurface in order to dampen their fluctuating production. In this study, a CAES scenario is numerically simulated within an idealized anticline porous formation. The pressure fluctuation in the reservoir during cyclic operation is within the required system pressure thresholds while yielding the required production rates. The large-scale pressure response in the storage formation is mainly caused by the initial air fill. Deliverability of the reservoir formation is estimated at 208.5 kg/s air for 30 h, corresponding to 9.8% of the stored air. The maximum production rate is estimated at 336.7 kg/s for 30 minutes.
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Effects of H2 and CO2 Underground Storage in Natural Pore Reservoirs - Findings by SEM and AFM Techniques
Authors S. Henkel, D. Pudlo, D. Albrecht, V. Reitenbach, L. Ganzer and R. GauppSummaryThe H2STORE project is a BMBF founded collaborative project. The main objective of the subproject at the FSU Jena are investigations on experimentally induced mineralogical-geochemical variations in potential reservoir and caprocks affected by a H2/energy storage at depths. In this experiments samples from five different stratigraphic units, representing the major siliciclastic hydrocarbon reservoir units in Germany, are analyzed. These rocks differ in their time of deposition; facies and detrital composition; burial history and therefore in their diagenetic, pressure and temperature evolution over time and formation fluid compositions. To classify the effects of a potential H2/CO2 storage at depths different kind of sample material (plugs, thin sections and rock fragments < 3.0 mm) are used for autoclave batch experiments with induced H2 (CO2) exposure under reservoir conditions (p, T, synthetic formation fluid) for time periods of 4–6 weeks. Before and after the experiments the exactly same material was analyzed by light microscopy, FE-SEM, AFM and BET. Also formation fluid analyses before and after the experiments were investigated by ICP-MS and ICP-OES. Dissolution structures on mineral surfaces, an increase of the specific surface area and element enrichment in formation fluid indicate mineral dissolution of e.g. Ca (Mg)CO3 and CaSO4 during the experiments.
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Basin Resources and Carbon Storage
Authors K. Michael, S. Varma, S. Whittaker, E. Bekele, L. Langhi, J. Hodgkinson and B. HarrisSummaryProspective sites for geological storage of carbon dioxide target sedimentary basins as these provide the most suitable geological settings for safe, long-term storage of greenhouse gases. Sedimentary basins can also host different natural resources including groundwater, oil and gas, unconventional gas, coal and geothermal energy.Understanding the nature of how these resources are distributed in the subsurface is fundamental to managing basin resource development and carbon dioxide storage.
The underlying principal of the proposed workflow is to assess what basin resource – storage interactions are likely and to evaluate, at different scales, how they may be best managed. For regions having potential for resource conflicts a basin resource management plan may be required, and the appropriate regulator would need to decide on the priority of each resource and, if parallel development is not feasible, the order in which resources should be exploited.
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Development of a 3D Online Planning Tool for the Evaluation of Potential Underground Energy Storage Areas in S.-H.
Authors M. Nolde, M. Schwanebeck, F. Dethlefsen, E. Biniyaz and R. DuttmannSummaryWe would like to present a GIS-based 3D online planning tool for underground energy storage. Its aim is to provide a basis for a pre-selection of possible sites for thermal, electrical, and substantial underground energy storages. The primary task of the proposed tool is to assist local authorities when dealing with the security of energy supply regarding the safe subsurface energy storage in the German state of Schleswig-Holstein. Taking into account as many of the relevant input factors as possible, the tool aims to suggest appropriate sites for setting up a selected kind of underground energy storage. The data base incorporates the current situtation as well as different energy related future scenarios.
The system is implemented as an online 3D server GIS environment, with no software needed to be installed on the user side. The results, representing areas potentially suitable for underground energy storage, are visualized as interactive 3D graphics and 2D maps in the browser. They can be downloaded in Geomodelling and GIS file formats for integration into an existing workflow.
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Current Status and Further Needs in Parameterization for an Underground Land Use Planning
Authors F. Dethlefsen, S. Bauer and A. DahmkeSummaryThe wide spread utilization of the subsurface for energy (heat) and mass (gas) storage in future requires an underground land use planning in order to be conducted efficiently and safely. The definition of underground compartments discriminating between spaces of utilization, induced effect, and monitoring is introduced. Numerical scenario simulations help to predict impacts of such underground uses and furthermore to determine sensitive parameters either regulating the induced processes or being influenced by these. For this task, parameters of geological features, of processes occurring underground, and of the intended storage demand are needed. This study presents an overview of the ANGUS+ joint research project focusing on this synoptic approach, further visualizing parameter availabilities as well as their uncertainties. Thus the needs for focusing further parameter acquisition aiming at an improvement of the mentioned scenario simulations and their expressiveness are deducted.
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Shallow Drilling in the NSB - Characterising CO2 Storage Systems via Detailed Mapping and Imaging of Glacial Stratigraphy
Authors A.K. Furre, H. Stewart, M.A. Stewart and P. AagaardSummaryCenozoic sediments of the North Sea Basin (NSB) have global importance for two reasons. Firstly, they record the glacial and interglacial history of environmental change in the Northern Hemisphere. Secondly, they overlie and seal operational and planned sites for the engineered storage of carbon dioxide (CO2), to store captured greenhouse gas emissions from power plant and industrial sources in Europe. Remarkably, the 1000 metre-thick Quaternary sediments are poorly sampled, bypassed to reach hydrocarbon resources in deeper strata.
This paper describes the work of the GlaciStore consortium who presents a revised seismostratigraphic model for the Quaternary strata of the NSB and studies of the extent of interconnecting, stacked networks of tunnel valleys. The consortium have used these studies to submit a drilling proposal to the International Ocean Discovery Program (IODP) where direct sampling will resolve the number of glacial cycles, improve understanding of groundwater layering and the implications of glacial landforms within the sequence, and quantification of geomechanical effects from fluctuating ice thicknesses (e.g. compaction, rock strength and stress profiles) on these sediments.
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Gravity-driven Convective Mixing of CO2 in Oil
Authors J.W. Both, S.E. Gasda, I. Aavatsmark and R. KaufmannSummaryInteraction between CO2 and oil exhibits complex phase behavior that results in gravity-driven convection and enhanced mixing of CO2 in the oil zone. We have shown that the density of oil increases between 4% and 6% at CO2 concentrations between 65% and 75% by mass. Different cubic EoS give different values for density of CO2-oil mixtures. The increase in oil density leads to an unstable density inversion, instigating convection in a 100 mD aquifer in a few days. The convection enhances the rate of CO2 uptake in the oil, with long-term steady rates from 500 kg/m2/y up to 800 kg/m2/y. The rate has some dependency on the EoS assumed in the computational model. The convective process substantially increases CO2 uptake in the oil zone compared to the diffusion process alone. Enhanced CO2 uptake has important implications for injection into depleted reservoirs and EOR/EGR operations, which is the subject of future work.
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Fluid Issues when Modeling CO2 Reinjection into a Fractured Reservoir Gas Field
Authors S. Thibeau, A. Kamp, I. Kospanova and J. François-BrazierSummaryCO2 reinjection into a fractured reservoir is challenging, as reinjected CO2 may recycle rapidly to the gas production wells, leading to potential gas production losses.
Development studies require performing screening studies, looking at many possible scenarios (as geological model, well location, process capacity). It is hence critical to speed up the simulation time in order to be able to investigate these many scenarios.
Various fluid models, with various degrees of simplification, may be used to study different phenomena that will impact the CO2 break through time. This includes convective flow in the fracture network, CO2 diffusive flow into the gas bearing matrix blocks, and CO2 dissolution in the formation water.
Specific fluid models, embedded in the reservoir model, were used in order to look at the impact of these various phenomena for the different scenarios, in order to speed up the developement process. This is presented in more details for the modeling of the molecular diffusion into the matrix blocks and the modeling of the convective flow in the fractures.
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The Ketzin Pilot Site for CO2 Storage in Second Year of the Post-closure Phase
Authors S. Martens, F. Möller, C. Schmidt-Hattenberger, M. Streibel, A. Szizybalski and A. LiebscherSummaryThe Ketzin pilot site for geological storage of CO2 located about 25 km west of Berlin was the first European pilot site for onshore storage of CO2 in saline aquifers. A total amount of 67 kilotons of CO2 was injected without any safety issues between June 2008 and August 2013 when the injection ceased and the site entered its post-closure phase. Within this phase a multidisciplinary monitoring program continues and the five research wells are stepwise abandoned in order to address and finally close the entire life cycle of the storage site. In October 2014, a two-week field experiment was carried out with the aim to back-produce parts of the injected CO2 and to study the reservoir and wellbore behaviour. In this contribution, we present a comprehensive overview on the status of the Ketzin site in its second year of the post-closure phase and the main results of the field experiment on CO2 back-production.
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Reactive Transport Modelling of CO2 Injection into a Carbonate Formation, Middle East
Authors T.J. Tambach and J.R. SnippeSummaryThis study describes injection of CO2 into a carbonate formation in the Middle East, which is considered as potential option for permanently storing CO2. It is predicted that CO2 predominantly migrates into a high permeability layer near the top of the reservoir and reaches a potentially conductive fault at the end of the injection period. Seepage of CO2 may occur along this fault during the post-injection period, causing upward migration of CO2 throughout the formation. The results show that CO2 dissolution and dissociation causes lowering of the pH to 4.7 in the plume, as well as some calcite dissolution. The molality of elemental Ca increases several orders of magnitude, although the amount of calcite dissolution remains limited. This suggests that the geochemical impact is relatively small in case of the closed system studied. The computed porosity changes are relatively larger than those computed for the SACROC carbonate reservoirs, where CO2 was injected for enhanced oil recovery. This is explained by mineral precipitation and possibly by higher initial Ca molalities in the SACROC modelling study.
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Dolomite Dissolution Rates at Conditions Relevant to CO2 Sequestration in the Rotliegend Gas Fields in NE Netherlands
Authors A. Baritantonaki, P. Bolourinejad and R. HerberSummaryThe kinetics of dolomite dissolution have been investigated in experiments conducted at conditions characteristic of the Rotliegend gas fields in the northeast of the Netherlands (Temperature 100 oC, Brine ionic strength I>6.4M, pH=2–5). Experiments were performed in closed, stirred, batch reactors at far from equilibrium conditions, with dolomite powders of different diameter fractions: 20–25 microns, 75–100 microns, and 300–350 microns, with respective geometric surface areas: 935cm2/g, 225 cm2/g and 65 cm2/g. Dissolution experiments were also conducted in deionized water for the largest grain size to determine the effect of solution composition on dolomite kinetics. The rates were deduced from the change in the amount of Mg2+ released in brine with time and were normalized by the surface area of the minerals at each time interval.
Dolomite dissolution rates were faster in brine than in deionized water by almost a factor of 2, which was not anticipated in such high salinity brine. Ionic strength and ion pairing overshadow the common ion effect, thus enhancing dissolution. In this work, smaller grains exhibited faster rates after normalization for surface area.
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Impact of SO2 Coinjection on the Reservoir - A Modelling Sensitivity Study
Authors J.L. Wolf, D. Rebscher, A. Niemi and J. BensabatSummaryReactive transport simulations were performed in order to assess the impact of impure CO2 containing SO2 on the geochemical reservoir system in carbon capture and storage (CCS) scenarios. For the numerical computation the recently released code TOUGHREACT V3.0-OMP was applied. Special emphasis is given on the aqueous chemistry of SO2, which rapidly dissolves into the formation water. Therein two different models using a kinetic as well as a thermodynamic approach were included. These allow for evaluation of transport related effects, resulting in different spatial distribution patterns of SO2 and subsequent changing chemistry involving minerals, in particular carbonates. The main focus of the presented work lies on the systematic variation of selected input parameters and the sensitivity of the numerical results on these initial conditions. In summary, the most prominent parameters determining the geochemical changes of the reservoir system are the initial concentration of SO2 as well as the type and amount of carbonate minerals available for pH buffering.
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Investigating the Relationship between Microstructural Properties and Geomechani Characteristics, Iranian Reservoir
Authors B. Mehrgini, H. Eshraghi, H. Memarian, A. Ghavidel, M. Hassanzade and M. NiknejadSummaryReservoir geomechanical evaluation provides powerful insights to understand and more precisely predict the lifetime behavior of reservoir regarding to the given or desired development plan. Any geomechanical evaluation is directly based on the rock mechanical data which is taken from experimental destructive tests on intact rock samples. However in some situations preparing required undisturbed and intact rock samples is impossible, technically or financially. Investigating the relationship between some microstructural properties and key geomechanical characteristics may lead to develop some models to estimate those geomechanical parameters by thin section studies instead of destructive tests. In this study which is done on 15 carbonate plugs of Iranian gas field, first qualified plugs were chosen based on the CT-Scan images to investigation. Second thin section studies were carried out on each trim of plugs both qualitatively and quantitatively. In the next step, uniaxial compression tests were performed on the samples. Investigations results illustrate that microstructural parameters including porosity, mud percentage and anhydrite cement content are the main affecting features on unconfined compressive strength (UCS) and Young’s modulus (E) of studied carbonate samples.
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Research on a Thermally Loaded Rock -Perspectives of Underground Thermal Energy Storage
Authors J. Franěk, J. Holeček, V. Hladík and K. SosnaSummaryThe research of thermally loaded rocks and UTES were examined in a geological environment at temperatures about 90 °C. Long-term in-situ experiment was placed in the SP-47 adit in the Underground Research Laboratory Josef, Mokrsko, Central Bohemia. The elevated temperature reached distance 3 m far from a heater. At the end of the cooling the rock massif was cooled to the natural temperature (9 °C). The maximal efficiency was 23 %. Fluctuations in heating intensity induce rapid increase / relaxation of stress and strain in the rock massif. The extent of induced stress reaches farther than the extent of elevated temperature. Thermally induced strains are almost completely reversible. Only a surface of the rock may occur irreversible changes. Significant thermally induced stress is of the same order of magnitude as tensile strength of the bulk rock massif. Thermal load of the rock mass has a measurable effect on the hydraulic permeability of the rock environment and composition of the percolating underground water. Chemical composition of groundwater was influenced by the presence of Na-silicate based geopolymer and by the ambient properties (elevated temperature, evaporation, contact with air etc.) Hydraulic properties were influences by thermal stress and relaxation during the heating/cooling cycles.
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Advanced Composite Materials for Coiled Tubing Deep Drilling Applications and Offshore Production Riser Systems
More LessSummaryThe oil and gas industry has proceeded to utilize offshore fields in ultra-deep water depths, and the geothermal exploration is going to deeper reservoirs in harder rock. Thus, application of existing technologies in those environments impose technical and economic challenges, e.g. high offshore riser system weight, indicating the need for alternative, innovative products and solutions. In order to meet mentioned challenges of deep offshore and geothermal drilling applications, advanced composite materials have been evaluated for their use in in such environments. As an example a self-supporting composite riser system concept has been designed and analyzed for deep water applications, and a coiled tubing demonstrator unit has been setup in Bochum for the testing of such materials.
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Does Injected H2 Induce Interactions among Brine and Minerals in Reservoir? An Equilibrium Geochemical Modelling Approach
Authors N. Hassannayebi and S. AzizmohammadiSummaryGeochemistry plays a great role when assessing the impact of hydrogen storage. With the purpose of discovering and characterizing minerals-brine interactions as a consequence of hydrogen injection into a depleted gas reservoir, we constructed an equilibrium geochemical model using, GEM-Selektor (GEMS) package. A depleted gas reservoir from upper Austria, Molasse basin, has been selected as a candidate for hydrogen storage. Thermodynamic model of formation water and minerals at in situ condition (P = 107 bar, T = 40°C) was created to represent initial state of the system, then the system re-equilibrated by introducing hydrogen. Over the course of hydrogen injection, decreasing trend in the contribution of H2 to reactions in aqueous, gas, and mineral phases is observed, pH value increases immediately after hydrogen introduced into the system and interactions among minerals and brine are observed. Both minerals dissolution and precipitation are observed to maintain the equilibrium. Brine data reveal slight variations for aqueous species at the beginning of hydrogen injection and rapid changes when higher amount of hydrogen injected into the system. The results are achieved based on some assumptions such as considering hydrogen to be highly reactive and giving infinite time for reactions (equilibrium calculations).
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Carbonated Brine Effect on Wellbore Cement Degradation in Contact Zone with Formation Rock
More LessSummaryThe objective of the work is to examine the cement-formation rock interface, under sequestration conditions. During the laboratory experiments the composed cement-rock samples were exposed in three cycles, to carbonated brine, under simulated underground conditions in order to determine rock and wellbore cement alteration. The rocks which were taken into account are sandstones and shale. The performed examination indicates that both cement and formation rock react in CO2 saturated brine under the experiment conditions. Most of the examined samples provide evidence for dissolution and corrosion processes. With progressing run time the corrosion and dissolution intensify.
The alteration of the cement-rock interface is strongly dependent on the rock lithology, which includes rock structure (mainly porosity) and mineral composition. It was found that in consequence of some rocks’ components dissolution the cement-rock interface may be a pathway, where there is a possibility of flowing pore waters rich in CO2 to come into contact with the wellbore cement.
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Probabilistic Seismic Hazard Analysis of Induced Seismicity Associated with Deep Geothermal Energy Production
Authors J. Schlittenhardt, T. Spies and T. HorstmannSummaryIn the course of planning and licensing, but likewise for the development and operation of deep geothermal systems, estimates of the frequency of exceedances of limits of ground motion are of interest. The limiting values used for evaluation of ground motion (PGV, Peak Ground Velocity) were taken from engineering regulations (standard value for perceptibility of vibrations, German DIN 4150 ). We developed a PSHA (probabilistic seismic hazard analysis) model for ground motion of induced seismicity. Thus, it is possible to specify the probability of exceedance of limiting values of PGV and to decide (e.g. by the regulator responsible for commissioning) whether the number of exceedances at these given limits are acceptable at a site or not. Additionally, hazard curves of induced and natural seismicity are compared to study the different impacts. Preliminary results which were derived using data from the operation phase of a plant, - for stiff soil, ignoring site effects - indicate higher frequencies of exceedance for induced seismicity than for natural seismicity only for low PGV values. The current work aims at refining our PSHA model by incorporating effects of local site conditions. They will be quantified using a concept of ambient seismic noise array measurements.
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Estimating the Geothermal Potential of the Tunnel lining Heat Exchanger Enhancement with Thermally Conductive Matter
More LessSummaryUtilization of the rock massif by tunnels or utility corridors as a heat source or heat storage leads to energy savings. This work presents an evaluation of a heat exchanger enhancement with a thermally conductive matter (TCM) in tunnel lining. The heat exchanger with TCM is meant to be placed between the primary and secondary lining. The evaluation is based on a finite element simulations. Also the influence of the heat exchanger tube spacing was investigated. The extractable heat from the rock massif ranges from 10 to 90 W per meter. The heat exchanger conductivity enhancement resulted into 4 to 30 % benefit.
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Feasibility Study on Seismic and CSEM Monitoring of CO2 Injection Based on Laboratory Acoustic and Resistivity Measurement
Authors J. Park, G. Sauvin, M. Soldal and B. BohloliSummaryIn this work, we apply a set of acoustic velocity and electrical resistivity measured during CO2 core flooding laboratory test in order to explore the sensitivity of field-scale data through a synthetic 1D model. We demonstrate the feasibility of monitoring CO2 injection into subsurface by geophysical means. So far, seismic and CSEM data were considered into the scope of work. In near future, we may also integrate gravity data.
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Solubility of Nitrogen and Oxygen Gas in Aqueous NaCl Solutions for Elevated Temperatures and Pressures
More LessSummaryCompressed air energy storage (CAES) is considered a possible option for storing energy from renewable production. Using geological porous formations for compressed air energy storage is viable. The solubility of compressed air in the highly mineralized formation water determines the total amount of dissolved gas and the magnitude of possible water-rock interactions. An accurate model for compressed air solubility under different temperature, pressure and salinity conditions is thus required to study the induced effects of compressed air energy storage in porous formations. Based on the principles of thermodynamics, we established the compressed air solubility model and expressed it as a polynomial formula, which consists of Henry’s constant, Poynting Factor, fugacity coefficient and activity coefficient, as well as partial pressure of each component in gas phase. By parameterization, we can directly use the model to work out solubility conveniently under various given conditions. For the model, the appropriate ranges of temperature, pressure and solution concentration are 273–373 K, 0.1–50 MPa, 0–5 mol/l of NaCl concentration. We have established a computer program for the model, which is also coupled with OpenGeoSys for reservoir simulation purposes and can thus be used in future work on CAES induced geochemical effects.
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No Short-term Attenuation of Methane Leaked into Shallow Aquifers - An Experimental Study
More LessSummaryA major concern about underground methane storage facilities culminates around effects of accidental leakages into shallow aquifers, especially if these are used for drinking water production. Amongst the biogeochemical reactions expected to follow such a leakage, sulfide generation is known to damage water supplies the most. Reduction of sulfate by methane oxidation also occurs in seafloor environments, which is much better known by both field and experimental studies.
Investigating the hydrogeochemical consequences in a shallow aquifer caused by a potential methane intrusion makes parametrization of models describing such processes possible. These findings should be considered at leakage monitoring and risk assessment of subsurface methane operations.
Flow-through column experiments were used to test different sediments percolated by different, methane-enriched groundwaters. These one-year-long experiments showed no significant oxidation of methane by oxygen, nitrate or sulfate, meaning that methane oxidation is inhibited in the studied system and time scale.
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Particle Swarm Optimization Inversion of Self Potential Anomaly for Detecting Coal Fires, a Case Study - Jharia Coal Field
Authors B.B. Singh, V. Srivardhan, S.K. Pal, S.K. Kanagaraju, S. Kumar and J. VaishSummaryDetection of coal fires at an early stage is very important for its control and mitigation operations. Coal fires induce fractures and cracks in the subsurface which accelerate the rate of combustion. In this work we demonstrate the usage of a novel approach in detecting coal fires and delineating these fractures using Self-Potential surveys and Particle Swarm Optimization inversion. The study area is take in the East Basuria colliery, Jharia Coal Field, Jharkhand, India and inversion results are compared with litho logs drilled in the region. The inversion scheme was tested on synthetic SP response in the presence of random noise. For the case study the causative source was modelled as inclined sheet like anomalies for SP survey undertaken in the region. The results demonstrate the robust performance of the algorithm and illustrates the usage of this novel approach in detecting coal fires for control and mitigation operations.
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3D Characterization of Saline Underground Formations with Investigative Geophysical Methods
Authors C. Hartmann, S. Uchtmann and D. OrlowskySummaryThe utilisation of the earths’ ground as one of the fundamental resources is one of the mankinds responsibility to secure sustainable conditions for human life on earth. There is an increasing demand for finding new natural resources as well as developing large natural underground capacities for the sustainable storage of these resources. Underground storage capacities may be furthermore used for other storage purposes: radioactive waste, carbon dioxide (CO2), water and energy (e.g. hydrothermal, gravitational).
For a more optimized utilization of saline formations as a location for new storage capacities new cavern structures need to be established in areas closer to lateral boundaries of the salt formation. Thus, the success of the development of new storage capacities highly depends on the quantity and quality of detailed structural information and the generation of a most realistic geological model.
New geophysical investigation technologies allow an integrated exploration of the inside and outside of complex saline formations such as salt domes. Salt formations are a favourable environment for numerous storage facilities. Two geophysical investigation technologies will be presented that appear to be significantly competent for the assessment of saline underground formations: 3D seismic reflection method, and 3D borehole ground penetrating radar (GPR) technique.
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CO2 Storage Potential of the Norwegian Continental Shelf
Authors M. Bjorheim, F. Riis, J.M. Mujezinovic and E. HallandSummaryA CO2 storage atlas of the Norwegian Continental Shelf (NCS) was elaborated by the Norwegian Petroleum Directorate (NPD) on request from the Ministry of Petroleum and Energy in the period 2011 to 2013 (npd.no).
The atlas documents the distribution and properties of the main aquifers, which are evaluated to have an interesting storage potential for CO2. The procedure for compiling the atlas was to screen all reservoir formations between 700 and 3500 m depth. In order to avoid conflict of interests with the petroleum industry, studies of CO2 injection into saline aquifers were mainly restricted to areas where the generation and migration of hydrocarbons is considered to be limited.
The results/ atlas material is now available on an interactive map called CO2 FactMap. This application gives you the possibility to explore the assessment result, and is also suited for mobile devices.
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Mapping of CO2 Storage Possibilities on The Norwegian Continental Shelf
More LessSummaryThe Norwegian Petroleum Directorate (NPD) has mapped and evaluated possible storage sites on the Norwegian Continental Shelf (NCS). The evaluation is published in three CO2 Storage Atlases: Norwegian part of the North Sea (2011), the Norwegian Sea (2013) and the Barents Sea (2013) (Halland et al.). The study is based on detailed work on all relevant geological formations and hydrocarbon fields on the NCS. In total 27 geological formations have been individually assessed and grouped into saline aquifers. In addition, several mapped and dry-drilled structures and abandoned hydrocarbon fields have been evaluated. The largest storage capacities are mapped in the mature part of the North Sea, where several saline aquifers and basins are evaluated. Compared with the areas in the North Sea and the Norwegian Sea, the Barents Sea areas is an immature petroleum province, with high exploration activity.
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Experimental Tests and Modeling of Mudstone Cap-rock Behavior in H2s-Co2-Brine Systems
Authors K. Labus, K. Suchodolska and P. BujokSummaryAcid gas interactions with rocks are currently of interest due to greenhouse effect abatement, enhanced oil and gas recovery and energized fluid fracturing of unconventional formations. We performed a study, enabling the hydrochemical models, calibrated on the basis of experiments, considering the impact of CO2 and, H2S and their mixture on low permeability rocks, representative for the Upper Silesian Coal Basin (Poland and Czech Republic). Rock samples were placed in the autoclave filled with brine, and acid gas, to reproduce water-rock-gas interactions at the PVT regime of possible storage site. SEM microscopy and EDX spectroscopy of reacted samples revealed significant changes in their structure and composition. Dissolution of skeletal grains, was the most distinct in carbonates and chlorite, and led to the increase of cap-rocks porosity. Geochemical modeling, based on the experimental results, allowed for assessment of volume and amount of secondary minerals during simulated reactions in 10 000 years of storage, and amounts of gases sequestered. Maximum calculated mineral-trapping capacity for the cap-rocks, calculated based on the results of kinetic modeling, reached 28.2 kgCO2/m3 for pure CO2 injection model, 20.8 kgCO2/m3 and 5,8 kg H2S /m3 for CO2+ H2S co-injection, 5,9 kg H2S /m3 for pure H2S model.
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