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Third EAGE CO2 Geological Storage Workshop
- Conference date: 26 Mar 2012 - 27 Mar 2012
- Location: Edinburgh, UK
- ISBN: 978-94-6282-054-8
- Published: 26 March 2012
46 results
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Invited Keynote: From Longannet to Peterhead - the Goldeneye CCS project Continues to Move Forward
By P. GarnhamOver the past four years a consortium of Shell, National Grid and ScottishPower has been working together, sponsored by the UK Government to try to develop a commercial scale CCS project based on emissions from Longannet Power Station (coal-fired, and operated by ScottishPower) with storage in the Goldeneye reservoir
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On the Use of Contact Angle Measurements to Determine the Wetting Properties of CO2
Authors J.R. Mills and M. SohrabiThis work presents new findings on the interaction of CO2-brine at reservoir conditions using the drop shape analysis method to determine contact angle and interfacial tension. Water-wet behaviour was observed at subcritical and supercritical conditions on a representative selection of real reservoir minerals. This study addresses fundamental physical properties of rock-fluid interactions pertaining to fluid flow and trapping at the pore-level.
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Effect of Burial Depth on Deformation and Storage Capacity of Sandstone Reservoirs
By A. TorabiThe present study investigates the effect of consolidation (burial depth) on the deformation and fluid flow behaviour of sandstone and its possible effect on the storage capacity of sandstone reservoirs. Sandstones with different degrees of consolidation from a variety of burial depths have been studied through in-situ measurements in the field and further analysis of the samples. There is a correlation between deformation mechanism and consolidation of sandstone. Unconsolidated sandstones that deform at shallow burial depth show a weak cataclasis, while well-consolidated and cemented sandstones deform mainly by fracturing. The deformation mechanism will affect the fluid flow within the rocks. Permeability reduction from host rock to fault rocks is significant within consolidated sandstone. The slip surfaces show lower permeability, while fault lenses present higher permeability values when compared to other fault related rocks. This is due to the fact that deformation is localized within the slip surfaces, while fault lens partly includes remnants of undeformed host rock. The higher capillary pressures in some of the fault rocks may contribute to trapping of CO2 through capillary forces, although, low permeability and high capillary pressure usually hamper connectivity and fluid flow within the reservoirs.
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Impact of Top-reservoir Morphology on CO2 Sequestration
Authors J. Tveranger, P. Dahle, H. Møll Nilsen, A.R. Syversveen, J.M. Nordbotten, P. Abrahamsen and K.A. LieModels used for evaluating CO2 plume behaviour in the subsurface often employ simplified geological reservoir descriptions. Experiences from the petroleum industry show, however, that geological heterogeneities significantly influence fluid flow. The present study addresses the need for evaluating the impact of realistic geology on CO2 behaviour in the subsurface. We here demonstrate the effect of adding realistic complexity to the top reservoir morphology. A sensitivity matrix consisting of combinations of depositional and structural irregularities creating relief along the top of a reservoir was set up and the resulting models run in a fluid flow simulator monitoring CO2 plume dynamics. Results demonstrate the interaction between specific geological features and resulting plume behaviour and added retention capacity. Our study highlights the need to include realistic geology in models forecasting migration behaviour in subsurface reservoir.
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Capacity in a Depleted Gas Field - Relative Permeability Bites Back
Authors C. Annia, O. Tucker, C. Thompson and S. GoodyearStorage capacity is an estimate of the maximum amount of CO2 that can be stored in geological formations. All methodologies used to calculate it start with an estimation of the pore space available for CO2 injection based on mapped pore volume or inferred from production history. For depleted hydrocarbon fields the volume of hydrocarbons produced is known.
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Case Studies for Monitoring of CO2 Storage Sites, based on Ground Deformation Monitoring with Radar Satellites
Authors J. Granda, A. Arnaud, B. Payàs and B. LecampionInSAR (Interferometry for Synthetic Aperture Radar) technology is a spaceborne measurement method that uses radar satellite images to detect and measure ground deformation with millimetric precision. Measurements are taken remotely from space, making this an appropriate tool for measuring ground motion in difficult to reach remote areas and in almost all weather conditions, during day or night. The Stable Point Network (SPN) is an advanced differential interferometric chain which was developed by Altamira Information in order to process several raw radar images to achieve millimetric ground motion measurements. Results are provided in GIS format and can be received and analysed by CO2 reservoir engineers remotely without the need for site visits. International case studies will be presented for three CO2-storage sites. These sites have been selected because they differ in the several criteria: Site conditions (climate, surface …), stage of CO2-injection, amount of detected ground motion, density of measurement points and cause of ground motion. To summarise, ground motion studies using InSAR technology contain valuable information for pore pressure behaviour monitoring of CO2 storage sites, especially when InSAR ground motion measurement results are inverted and used for reservoir management and history matching of geo-mechanical models.
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Monitoring of the In Salah CO2 Storage Site (Krechba) Using Microseismic Data Analysis
Authors V. Oye, P. Zhao, D. Kühn, K. Iranpour, E. Aker and B. BohloliMicroseismic data recorded at the In Salah CO2 storage site (Krechba), Algeria has been analysed and interpreted. Based on the results of the single observation well and detailed information of the subsurface geological and geophysical model, we conducted a network design for improved location capabilities of future microseismic events.
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Baseline of Soil-Atmosphere CO2 Flux in the Hontomin Site (Burgos, Spain)
Authors L. F. Mazadiego, F. Grandia, J. Elio, B. Nissi, O. Vaselli, M. Ortega, J. Caballero, E. Vilanova, E. Chacón and J. LlamasCO2sc is planned to be injected in 2013 at the Hontomín site (Spain) as a part of the EC-funded OXYCFB300 project. The objectives of this project are: the development of knowledge, methodologies and technologies for industrial application of geological storage of CO2; the demonstration that industrial activity is feasible and safe; provision of support to the regulatory authority; and the promotion of scientific and technological training in CCS. During the stages of selection and characterization activities have been conducted on structural geology, hydrogeology and hydrogeochemical, geophysics, laboratory experimentation and modeling of behavior and injection of CO2, natural gas emissions, and risk analysis. CO2 is going to be injected in a saline reservoir (1500 m depth) hosted by Lower Jurassic limestones and sealed by Lower Cretaceous clay formations. As part of the site characterization, baseline of CO2 flux in the soil-atmosphere interface has been determined. This is an important task to detect leakage in the reservoir during the operational stage and post-closure of the storage. In case of failure of the seal, CO2 fluxes in conduits such as wells or faults are expected to significantly increase, and they can be easily detected by comparing them with those from the pre-injection stage.
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Using an Old Underground Blowout as a Proxy for CO2 Leakage Scenarios
More LessBased on seismic data acquired prior to an underground blowout in 1989, we find that it is reasonable to assume that there has been some gas migration into shallower sediments over a time period of 20 years. By studying the seismic datasets (several 2D lines and one 3D) acquired over this area, we can learn something about how fast gas migrates through shallow sediments close to the seabed. Since CO2 is denser and will probably flow slower than gas, we think it is possible to use this example as a proxy to estimate the lower bound for vertical transit times of CO2 through shallow sediments of the type we are studying. This knowledge we believe might be of importance in risk assessment associated with underground storage of CO2. However, the reservoir pressure and temperature conditions (that vary with depth) dictate the CO2 behaviour, whether it is supercritical with liquid-like densities or with gas-like viscosities. It is important to stress, therefore, that there are significant differences between CO2 in a supercritical phase and the assumed gas associated with an underground blow out from an oil well.
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Monitoring of Leakage from CO2 Stores in Shallow Groundwater Aquifers – Lessons Learned from Natural Analogues
By F. MayIn the case of leakage from a deep aquifer storage, ascending saline formation waters and CO2 can mix with fresh waters and react with shallow aquifer rocks. These processes reduce concentrations of chemical species in contaminant plumes and cause overlapping concentration ranges of chemical elements with back ground waters. Some examples are presented from areas where natural CO2 and carbonic water discharge together with fresh groundwater. The main reasons of uncertainty in leakage quantification are: natural variability of background waters, chances of plume detection in thick alluvial aquifers with high groundwater flow rates and the calculation of mass balances from geochemical point data obtained from limited numbers of observation wells. These inherent uncertainties have to be taken into account in the preparation of risk management and monitoring plans for groundwater protection, e.g. the choice of indicative chemical species and the definition of threshold levels for actions to be taken.
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Time Lapse Seismic Interpretation of CO2 Storage at the Snøhvit Field
More LessBased on time lapse amplitude variation with offset (AVO) data we present one possible interpretation of fluid and pressure effects due to CO2 injection at the Snøhvit field.
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MMV Plan
Authors I. Susanto, P. Wood, W. Berlang and E. MackieFor each CO2 storage project, a Measuring Monitoring and Verification (MMV) plan is created that describes how the operator aims to ensure public and environmental safety, verify storage performance and containment and, in case of leakage, quantify the amount leaked back to the atmosphere. To deliver the MMV aims, effective monitoring technologies have to be selected to address the site-specific risks. In this article, this MMV design approach is applied to the Goldeneye field, a gas reservoir, located 101km offshore North-East of Aberdeen, Scotland.
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An Open Source Numerical CO2 Laboratory
Authors K.M. Flornes, K.A. Lie, H.M. Nilsen, O. Saevareid and B. FlemischNumerical simulation tools are essential in the assessment of potential CO2 storage sites. We will present a new suite of open source simulation tools built on modern software principles. The simulation suite is the result of a collaborative effort by several research groups in Norway and Germany. The goal is to bridge the gap between academia and industry and accelerate the transfer of new methods and modeling options. A set of validation studies using synthetic CO2 benchmark problems and real data from the Utsira injection site will be presented.
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Pore Scale Modelling of CO2 Storage in the Utsira Formation
Authors T. Ramstad, H.G. Rueslåtten and E. LindebergDigital pore scale images of the reservoir rocks from the Utsira formation have been modelled. The Utsira Formation on the Norwegian Continental Shelf that is already being used for CO2 sequestration. This is a saline sand aquifer of Miocene to early Pliocene age, which is covered by some 700 meters of shales and sands. The aquifer is large and CO2 is being injected into the aquifer at a depth of 1012 meters below the sea floor by a highly deviated 3 km long well from the Sleipner Field. Direct dynamic CO2/water simulations have been conducted with all relevant fluid and flow properties. From these simulations steady and un-steady state constitutive relations (relative permeability, end-point saturations) are obtained. Clear flow rate and viscosity effects are revealed from these data, which again affects the storage capabilities of the reservoir rocks.
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The Effects of CO2 on Reservoir and Seal Quality during Storage in Depleted Rotliegend Gas Fields in NE Netherlands
Authors P. Bolourinejad and M.A. HerberThe effects of CO2 storage on reservoir quality and caprock integrity have been studied for several potential storage sites in northeast of the Netherlands. These fields have the Permian Rotliegend as the reservoir, overlain by Zechstein carbonates, anhydrites and salt. Long term laboratory experiments were carried out in high pressure/ temperature condition on reservoir and seal samples in the presence of CO2, methane and brine. The results were then compared with the predictions from model simulations. Experiments and modeling results are in good agreement with respect to the nature of mineral dissolution and precipitation. However, deviation between modeling and experiment is observed with regard to the magnitude and time scale of changes in mineral dissolution and precipitation. In many observed experimental cases, both processes appear to occur more aggressively (i.e. faster and stronger) than predicted by the model. The probable reason for this deviation is uncertainty in the key modeling parameters such as activation energy and surface area of minerals. Exact knowledge of the brine composition is also essential.
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History-matching of CO2 Flow at Sleipner – New Insight based on Analyses of Temperature and Seismic Data
Authors C. Hermanrud, H.M. Nordgård Bolås, G.M.G. Teige, H.M. Nilsen and A.F. KIærHistory matching of layer 9 of the Utsira Formation in the Sleipner area has so far been problematic, but could be achieved it higher CO2 temperature than has previously been estimated are invoked. Such high temperatures can to some extent be justified from hithero unknown DST measurements. Furhtermore, heat exchange between warm injected CO2 and the colder reservoir can be significant. Such heat exchange may possibly explain the discrepancy between modelled and observed CO2 fow in the Utsira Formation.
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CCS in the Goldeneye Field, UK - A Geomechanical Assessment of Containment
Authors J. M. Davison, S. de Vries, J. Ita, L. Acevedo, A. Shinde, P. Fokker and R. WentinckFor any CCS project, geomechanics plays a key role in determining the containment of the injected CO2. The high potential routes for loss of containment include fracturing the caprock and/or migration along discontinuities through the caprock. Leakage processes are dominated by the in-situ stresses, formation pressures, injection pressures and temperature of the reservoir, all of which vary with time. Whilst injection of gas and fluids in subsurface formations is common practice, we identify key geomechanical challenges associated with CCS projects. These key challenges are explained within the context of the Goldeneye CCS project. Geomechnaical modelling was conducted for assurance of containment for the full life-cycle of the field. Numerical tools have been used to evaluate caprock integrity, reservoir deformation, fault stability and the impact of thermal cooling in terms of fracturing of the reservoir as well as the caprock. We also discuss the impact of thermal cooling adjacent to the injection well and the impact this could have on development of micro-annuli as potential leakage pathways. The results of the geomechanical analysis support injection of CO2 into the depleted Goldeneye reservoir which provides reliable containment over the planned injection period, as well as long-term sequestration within the storage complex.
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Reactive Transport Modeling for CO2 Storage in a Depleted North Sea Gas Field
Authors J. Snippe, L. Wei, C. Lovelock and O. TuckerThe key subsurface selection criteria for a CO2 storage candidate are capacity, injectivity and containment. There are many factors that influence these selection criteria. The factor addressed in this paper is the geochemical interaction between CO2 and the rock minerals. Each of the criteria can be affected by these interactions. For Goldeneye, a depleted gas reservoir in the Central North Sea, we have simulated the potential geochemical interactions with and without coupling to fluid flow. For the standalone interactions we used a standard geochemical modeling package (PHREEQC), using dissolution/precipitation rate formulas. For the coupled interactions we used our in-house reservoir simulator coupled to PHREEQC. The reservoir simulator was run in Equation of State mode so that it takes into account the phase behaviour between the gas (including CO2 – hydrocarbon mixing), oil (thin oil rim) and water. We also considered diffusion models through the caprock. The conclusion is that for Goldeneye the CO2-induced reactions tend to decrease porosity in the caprock as well as in the reservoir. Therefore it is considered unlikely that the geochemical interactions would create leak paths in the caprock. The porosity decrease in the reservoir is not likely to have a significant impact on injectivity.
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The Importance of Mineral Surface Areas Exposed to Open Pores in Rotliegend Sandstones for Modelling CO2 Water-rock Interactions
Authors S. Waldmann, A. Busch, L. Wei, K. van Ojik and R. GauppRotliegend reservoir rocks from the northern Netherlands were analysed in terms of mineralogical features, diagenetic mineral types and mineral surface areas which are exposed to open pores (effective mineralogy). The consideration of the effective mineralogy in comparison to the volumetric bulk rock composition of sandstones and the integration into CO2-water-rock simulation has shown that the mineral reactions are sensitive according to the initial data set. For the test scenario the results show that during CO2 storage especially long-term carbonate and silica reactions are affected. For the effective mineralogy data Mg-smectite stays in equilibrium with the solution which is caused by a higher initial amount of hematite and the release of iron for siderite precipitation. This reaction lowers the bicarbonate content in the solution and forces dolomite and ankerite to dissolve consequently. On the other hand Mg-smectite is unstable and carbonate minerals stay in equilibrium at the end of the simulation according to the volumetric mineralogy data.
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Business as Unusual - The Key Subsurface Challenges in Sequestration in a Depleted Gas Field
Authors O. Tucker, C. Lovelock, L. Acevedo and M. KosterWe are all well versed in developing oil and gas fields: understanding their key uncertainties and what is important to ensure a successful and safe development.
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CO2 EOR and Storage in Heavy Oil Reservoirs Underlying Permafrost
Authors A. Emadi, M. Sohrabi, A. Farzaneh, M. Jamiolahmady and S. IrlandInjection of the captured CO2 from industrial sources in oil reservoirs can alleviate negative environmental impacts of CO2 emission into the atmosphere and at the same time provides economic rationale for CCS by improving oil recovery. Compared to light oil, heavy oils have a much larger carbon footprint and hence, from environmental point of view, are more attractive targets for CCS. Heavy oil reservoirs are usually produced by thermal recovery techniques which only exacerbates adverse environmental effects of oil production from these reservoirs. Heavy oil reservoirs can therefore be good candidates for combining CCS and EOR. Examples of such reservoirs are found on North Slope, Alaska, where huge heavy oil resources exist in shallow reservoirs at exceptionally low reservoir temperature because of permafrost. This paper presents the results of a series of coreflood studies using a heavy crude sample from a permafrost region. The experiments compare CO2 storage capacity of the rock sample at reservoir conditions under different injection strategies and determine the additional recovery as a result of CO2 injection. The results show that CO2 injection doubled the heavy oil recovery by plain waterflood however the storage capacity of the rock was not significantly affected by the injection strategy.
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Significant Improvement in Oil Recovery and CO2 Storage by Carbonated Water Injection (CWI)
Authors M. Tavakolian, M. Sohrabi, M. Jami and S. IrelandCWI can alleviate many of the shortcomings of conventional CO2 floods. As a single phase (water and dissolved CO2), carbonated water (CW) does not exhibit fingering problem when injected into the reservoir since the mobility contrast between oil and CW is less than what it would be in the CO2-oil system. Consequently, a much better sweep efficiency (compared to CO2 flooding) can be obtained and hence CO2 would be distributed within a larger part of the reservoir. Furthermore, the higher density of carbonated water (compared to water) prevents CO2 gravity override eliminating the risk of leakage of CO2 through cap rock. In this paper, we present the results of a series of coreflood experiments using sandstone cores and real crude oil. The brine used in the coreflood experiments represented Seawater which is usually injected in oil reservoirs. The experiments were carried out to compare the performance of CWI with plain (conventional) water injection and CO2 flooding. The results of both secondary (pre-waterflood) CWI and tertiary (post-waterflood) CWI reveal that CWI is an efficient oil recovery method compared to conventional waterflooding and leads to safe storage of significant quantity of CO2 as a dissolved phase.
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Moving CO2 EOR Offshore
Authors S. Goodyear, M.P. Koster, K.A. Marriot, A. Paterson, A.W. Sipkema and I.M. YoungCO2 is the dominant anthropogenic greenhouse gas that is believed to be driving global warming. Carbon capture and storage (CCS) can contribute to reducing CO2 emissions. However CO2 capture from flue gas sources with current technology is CAPEX and energy intensive, so that the cost of CO2 abatement with CCS is high.
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Compaction Driven Flow in Porosity Waves - A Threat to Caprock Integrity?
By N.S.C. SimonCompaction of porous rock is a mechanism to maintain or increase fluid overpressure and may lead to fluid focusing and the development of porosity waves. Such fluid transport may be much more efficient than Darcy flow or even fracturing and is predicted to play an important role in sedimentary basins, during crustal metamorphism and for mantle melt extraction. Here I investigate the possibility of porosity waves occurring during injection and storage of CO2 in aquifers. Reaction induced compaction may be expected in CO2 storage because of the large thermal, mechanical and chemical disequilibrium that is introduced to the system by human activity, and due to high reactivity of CO2 dissolved in brine. First results indicate that low permeability caprock may fail as a barrier to flow if significant viscous compaction occurs. In laboratory experiments, such deformation has been shown to take place due to the high reactivity of CO2-rich brine. However, the temporal and spatial scales for the onset of focused flow in porosity waves strongly depend on a set of poorly constrained parameters. Thus, more experimental and numerical work and comparison to field data is needed to correctly assess these coupled reaction-deformation-flow processes.
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Fluid Dynamics of CO2 Migration within and out of Geological Storage Reservoirs
By U. WeyerThe obvious discrepancy between Muskat’s (1937) concept and the physics of Hubbert have not yet played a decisive role in Reservoir Engineering as indicated by the huge economic success of the petroleum industry. The geological storage of CO2 is, however, a paradigm changer as reservoir conditions shift from sink conditions during petroleum production to source conditions when geological storage of CO2 is applied. The simulators of the petroleum industry and the methodology used are not well-suited to deal with these source conditions. Hubbert’s Force Potential and Groundwater Flow Systems analysis should be applied in selecting storage sites and in simulating flow paths with mathematical models based on the proven methodology of advanced hydrogeology. Applying correct physics to the long-term migration of CO2 by using existing models of regional groundwater flow determines the eventual discharge points of injected CO2, and the estimated time span involved. If the injection sites are properly selected, then these time spans will exceed thousands or tens of thousands of years before the CO2 would enter surface waters. Geochemical processes will potentially also have significantly reduced the amount of CO2 discharged at that time.
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Association between Discharge Areas of Groundwater and Volcanic CO2
Authors U. Weyer, F. May and J.C. EllisDischarge areas of groundwater flow systems determine the discharge points for CO2, be it of volcanic origin or, in the future, from geological CO2 storage.
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Who are Communicating CCS in Norway?
By A. KlimekBoth engineering approaches and political approaches are crucial if CCS is ever to become a technically functioning option. But both tend to reduce CCS to a mere technical or political problem. Carbon capture is afflicted with an increasing complexity and I argue that it cannot be understood or even explained in a single way. If a new e. g. technology shall be implemented you have to make sure that you will not encounter resistance. A various number of theories offer good examples and ways to inform or even involve the public into implementation processes. Again and again it gets visible that the ‘general public’ is more than a homogenous crew, where decision processes can calculate by means of graphics. The general public needs more than just information. Various implementation processes demonstrate that new technologies can collapse without public benefit.
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Fracture-related Fluid Flow in Sandstone Reservoirs - Insights from Outcrop Analogues of South-eastern Utah
Authors K. Ogata, K. Senger, A. Braathen, J. Tveranger, E. Petrie and J.P. EvansFault- and fold-related fractures influence the fluid circulation in the subsurface, thus being of high importance for CO2 storage site assessment, especially in terms of reservoir connectivity and leakage. In this context, discrete regions of concentrated sub-parallel fracturing known as fracture corridors are inferred to be preferential conduits for fluid migration. We investigate fracture corridors of the middle-late Jurassic Entrada and Curtis formations of the northern Paradox Basin (Utah), which are characterized by discoloration (bleaching) due to oxide removal by circulating CO2- and/or hydrocarbon-charged fluids. The analyzed structures are located in the footwall of a km-scale, steep normal fault with displacement values on the order of hundreds of meters. They trend roughly perpendicular and subordinately parallel to the main fault direction, and define a systematic network on the hundreds of meters scale. The fracture corridors pinch- and fringe-out laterally and vertically into single, continuous fractures, following the axial zones of open fold systems related to the evolution of the main fault. Based on the presented data we hypothesize that such fracture corridors, connecting localized reservoirs at different stratigraphic levels up towards the surface, represent preferred fluid migration pathways rather than the main faults.
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Impact of Faults on the Mechanical and Petrophysical Properties of Sandstone Reservoirs - An Implication for CO2 Storage
Authors R.A. Alikarami, A.T. Torabi and E.S. SkurtveitTo assess reliable candidate reservoirs/aquifers for CO2 storage, enhanced understanding of the structure and the mechanical and petrophysical properties of strain localization zones in comparison to the surrounding undeformed rock is essential (Torabi 2007). To understand the possible effect of deformation structures on CO2 storage, a fieldwork was performed in the Navajo and Entrada sandstones in southeastern Utah to investigate the elastic and petrophysical properties of a fault core and damage zone. Deformation structures, air permeability and rock hardness have been logged along scan-lines perpendicular to the fault. In the foot-wall fractures are observed just within distance of three meters from the fault, but deformation bands are spread to about hundreds of meters. In the hangingwall fractures are observed in a distance of more than seventy meters, while deformation band have been concentrated within forty meters from the fault. Our preliminary results show a strong correlation between deformation structures intensity and distance from the fault, but weak correlation between Schmidt Hammer rebound and mini-perm values versus deformation pattern. The spread in the measured data might be related to variation in internal layering in the sand dunes, the orientation and weathering of the surface used for testing or other structural effects.
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Experimental and Modelling Study of the Dry-out during CO2 SC Injection in Reservoir Rock from the Hontomín Site (Spain)
Authors F. Grandia, A. Credoz, J. Torres, R. Solanas and L. VegaThe dry-out effect due to the dissolution of brine in CO2sc has been identified experimentally using samples from the reservoir formations at the Hontomín site. Injection of CO2 in this site is planned in 2013 in the frame of the OXYCFB300 EC-funded project. Samples from the Arcera Fm. have been selected for the experiments, and filled with NaCl-type brine. After 3 hours of injection of supercritical CO2 at 120 bar and 80 ºC, precipitation of halite is triggered leading due to dissolution of brine into CO2. This leads to permeability reduction in the first centimetres from the injection point. These experimental results have been reproduced in a reactive transport simulations using TOUGHREACT.
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Investigating the Link between Surface Deformation and Microseismicity Using Coupled Flow-geomechanical Simulation
Authors D. Angus, T. Lynch, P. Lorinczi and Q.J. FisherIn this paper, we investigate the relationship between surface deformation and microseismicity using coupled fluid-flow and geomechanical simulation. Since both microseismic and InSAR monitoring integrated with coupled fluid-flow/geomechanical modelling represent cost effective approaches in monitoring the containment of injected CO2, it is worthwhile exploring any potential link between microseismicity and surface deformation. Specifically, we simulate and examine the temporal and spatial evolution of microseismicity (see Angus et al., 2010) and surface uplift due to injection of CO2 for a faulted graben style sandstone reservoir model. We attempt to address whether there is a significant link between surface uplift and microseismicity, and if so, can we draw some relationship between rates of surface uplift and seismicity?
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Estimation of Thermodynamics and Chemical Kinetics Parameters at Different Scales for the Models of CO2 Storage
Authors J. Raveloson, D. Garcia, C. Helbert and B. GuyThe present work is based on the study of the water-gas-rock interactions in the case of CO2 storage in geological environment. The focus is on the scale of observation geochemical phenomena while taking into account the heterogeneity of the reservoir. This heterogeneity at small and large scale helps to maintain a local variability of the chemical composition of the fluid and influence reaction rates at the pore as well as at the reservoir scale We propose to evaluate the geostatistical characteristics of local variability thanks to simulations of reactive transport on a small scale in which parameters (namely the equilibrium constants log K and the rate constant k) are perturbed to represent local processes.
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Corrective Measures
By M. KosterWhen a CO2 store has been found to be leaking, one would expect immediate action to be taken. It is however important to first establish the exact migration path through the store. This is then followed by a risk assessment, which addresses the potential magnitude and consequences of the leak, before deciding on any appropriate actions to remedy the problem.
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Modelling the Reflectivity of a Carbon Dioxide Transition Zone
Authors J.L. Gomez and C.L. RavazzoliThe seismic monitoring of carbon dioxide in geologic reservoirs is mostly focused on the characterization of accumulations of high saturation, due to their large seismic amplitudes. Nevertheless, low-saturation zones with dispersed CO2, or saturation transitions may have an important role in the propagation of waves within the reservoir, giving rise to amplitude and phase changes of the seismic signals. In this work, we consider a transition layer given by a linear CO2 saturation-depth profile, which in turns develops a non-linear velocity trend with depth. We model the theoretical reflectivity response of a simple reservoir model, based on the Sleipner field, with a given CO2 saturation transition zone. Our study entails a parametric analysis of the generalized P-wave reflection coefficient and its variations with ray angle (AVA) and frequency (AVF). Our results suggest that the characterization of CO2 transitions zones can be achieved with a combined AVA and AVF analysis. We have shown that discrimination between thin and thick CO2 zones seems feasible. In addition, the bulk CO2 saturation present in the reservoir may be estimated by considering its reflectivity in the frequency domain.
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SCAL Programme for Goldeneye CO2 Storage
Authors S. Goodyear, W. Boom, P. Doe, A. Cable and D. MogfordSCAL data is an important input to the assessment of the Goldeneye reservoir for CO2 storage. A CO2 storage specific SCAL programme was undertaken comprising three stages: development of a conceptual framework for the displacement mechanisms; review of existing Goldeneye SCAL data and execution of a new SCAL tests. The high vertical permeability of the main sand and the aquifer influx under depletion required a non-standard set of measurements to be specified.
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CO2 Field Lab - Field Experience with Controlled Releases of CO2 at very Shallow Depths
Authors D. Jones, J.F. Girard, O. Kuras, E. Lindeberg, M Barrio, K. Royse, F. Gal, P. Meldrum, P. Pezard, A. Levannier, J. Desroches, D. Neyens, J. Paris and G. HenryThe objective of the CO2 Field Lab project is to determine the sensitivity of monitoring systems to detect shallow CO2 migration and surface leakage. To achieve its objectives, the project comprises two controlled releases of CO2 into the shallow and very shallow subsurface in a Norwegian aquifer in the Svelvik ridge (Figure 1).
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Microseismic Monitoring of CO2 Storage
Authors A. Stork, J. Verdon and J.M. KendallGeomechanical deformation, if it creates and/or reactivates faults and fractures, can provide a leakage pathway for CO2 to escape the reservoir. By monitoring microseismicity in and around the reservoir, the risks of leakage can be assessed. Although it is a mature technology for monitoring hydraulic fracturing in tight gas reservoirs, microseismic monitoring is still an experimental technique for CCS. To be of use for CCS sites, arrays must be capable of detecting events must across a wider area than typical frac-jobs. This poses a challenge to design suitable arrays within engineering and cost constraints. Another key issue is to determine how microseismic observations should be best interpreted with respect to leakage risks. So far we have found that linking event observations with geomechanical models - comparing predictions from various geomechanical scenarios with field observations - is an important aspect of event interpretation. In this paper we use a case example from the Weyburn CCS project, although our discussions have general application.
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An 'Inverse CCS Site' in NW Hungary – Geology and Modeling
Authors C.S. Király, M. Berta, Á. Szamosfalvi, G. Falus and C. SzabóThe research of natural analogues for future CCS projects is a dynamically growing sector of geoengineering. In our work this newly discovered aspect of a CO2 field is presented. In NW Hungary there is a field utilized for more than 60 years. Thus there is a large amount of data from hydrocarbon exploration, gas measurements, seismic sections, well logs, and porewater analysis. Modelling work is done to describe the interactions resulting in the experienced situation to provide an estimate for a planned CO2 reservoir similar to this natural analogue in pressure, temperature, hydrogeology, tectonics, and composition.
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The Effects of Aquifer/Caprock Interface on CO2 Storage Capacity and Security
Authors S.M. Shariatipour, G.E. Pickup, D. Stow and E.J. MackayIn simulations of CO2 storage in saline aquifers, it is often assumed that there is a sharp boundary between the aquifer and the caprock. However, this is not always the case. In many cases there is a gradual transition between sand-rich facies in the aquifer and mud-rich facies in the caprock. Moreover, some simulations assume a smooth interface, whereas typically the surface is irregular, due to sedimentological and stratigraphic effects or structural deformation. We have conducted a range of numerical simulations on a variety of heterogeneous aquifer/caprock models to investigate the impact of the different types of aquifer/caprock interfaces. Firstly, the nature of the interface can influence estimates of storage capacity. A transition zone between the aquifer and the caprock leads to uncertainty in the effective aquifer volume. Secondly, the aquifer/caprock interface can affect the security of CO2 storage. A transition zone can increase the security by providing partial baffles to hinder CO2 migration towards the caprock. Rugosity at the aquifer/caprock interface, may assist or hinder structural trapping. Small domes may provide extra storage volume. On the other hand, topographical highs may provide pathways for rapid migration of CO2 from the injector.
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Laboratory CO2 Migration Experiments for Evaluation of Potential Storage Sites in the Czech Republic
Authors V. Havlova, D. Dobrev, P. Bruha, V. Hladik, V. Kolejka and M. GeršlResearch activities within the presented project aimed at development of methodology for studying CO2 migration in reservoir rocks and caprocks under Czech Republic conditions. As the storage system cannot be observed directly in-situ, lab experiments should simulate the underground conditions as well as possible. This goal can be achieved only by maintaining the simulated injection conditions during the experiment course. This approach was the key element in the presented R&D work. The first achievement of the presented research was collection of information about potential storage sites in the Czech Republic, achievement of sample for candidate host rock type and their characterisation. Based on preliminary site selection and also on the availability of suitable cores, reservoir rocks from 3 geological structures were selected for the experiments: Carboniferous sandstones from the Central Bohemian Basin and 2 Neogene type sandstones from Vienna Basin, S. Moravia. Simultaneously a high pressure flow-through migration apparatus was successfully constructed, enabling dynamic laboratory experiments with supercritical CO2, reservoir rock samples and brines under reservoir p-T conditions. The device allows also measurements of sample permeability for water prior or after the CO2 migration. A set of experiments with rock samples was performed and evaluated.
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Passive Seismic Monitoring of Fluid Injection at the Longyearbyen CO2-Lab, Svalbard
Authors P. Zhao, V. Oye, A. Braathen and S. Olaussenyen is considered physically open, and, therefore, will likely experience drift of the injected CO2 towards the Northeast, through gradual mixing and expulsion of saline groundwater. This offers a unique opportunity for studying the behavior of CO2 in subsurface saline aquifers. Six slim-hole wells have been drilled so far and several new monitoring wells are planned in what becomes a “well park”. In this study, we try to use induced seismicity to monitor the injection fluid in the test site. A precise estimation of the location and magnitude of the microearthquake will be important to investigate the link between the injection and the sudden stress release as a microearthquake. In addition, the spatial and temporal patterns of the occurrences of microearthquakes might help us better constrain the migration pattern of the injected fluid.
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Validation of the Coupled Simulator OpenGeoSys-Eclipse
Authors S. Bauer, B. Graupner, K. Benisch, D. Li and C. BeyerThis paper presents the verification by benchmarking and code comparison of a coupled multi-phase and reactive transport simulator for CO2 storage simulations. Benchmarks of increasing complexity, dimensionality and process coverage are investigated. Differences in the results obtained with different simulators can in the case of multi-phase flow be assigned to the different mathematical and numerical methods used, in the case of geochemical reactions the underlying data base additionally influences the results significantly. This work thus stresses the importance of a consistent code verification for the complex numerical models required for assessing CO2 storage long term effects and risks.
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From Storage Potential to Storage Capacity - A Re-evaluation Method of 'Old' Well-logs
Authors G. Falus and A. SzamosfalviCarbon dioxide emitted worldwide as well as in Hungary is believed to contribute to climate change of our Planet. The increasing emission of greenhouse gases especially carbon dioxide imposes a significant climatic issue. Adequate alternative solutions have to be found on a limited time frame in order to answer the arising problems. Among all emission reduction methods CCS (carbon dioxide capture and geological sequestration) is the only available tool that can immediately produce dramatic cuts in carbon emissions, without drastically restructuring energy production. A major disadvantage however is the high cost of the activity. Therefore, all cost reducing opportunities must be exploited. The most direct way to obtain physical and geometric information about subsurface formations is using well bores. Information provided by the well-boring is indispensable in processing and interpretation of seismic data and determination of the exact geological setup of a formation. Therefore, well-log data of a given study area are of prime importance. We have developed a well-log re-interpretation method using old-paper based well-logs and tested the method on the most promising saline reservoir formation in Hungary to have a more accurate view of storage potential in Hungary.
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Efficiency of CO2 Storage in a Domed Structure
Authors G.E. Pickup, M. Jin, E.J. Mackay, J.D.O. Williams and M.S. BenthamWhen storing CO2 in a saline aquifer, it is desirable to have a structural trap, such as a domed closure, to limit the lateral migration of CO2. Domed structures may be formed in sandstone formations by migration of underlying salt bodies (halokinesis). In this study, we have created such a model of a hypothetical storage site in a domed structure, based on a real formation, using existing geological and petrophysical data. CO2 storage was simulated using the Eclipse 300 simulator with the CO2STORE module. Injection was initially controlled by rate, but was constrained by pressure build-up in the injection wells and at the crest of the dome. In additional, we monitored migration of CO2 past the dome spill point. A base case model was simulated and the a range of sensitivity cases investigated including the effect of aquifer size and heterogeneity. The results are very sensitive to boundary conditions. Notably, if the reservoir is open, the capacity may be limited due to migration across the spill point. The storage capacity also depends on reservoir heterogeneity, particularly if there are extensive layers of low permeability.
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Effect of Temperature and Calcite on Carbon Dioxide Transport and Hydrate Stability in Geological Formations
Authors V.C. Phan, T. Kuznetsova and B. KvammeAll of the simulated systems showed evidence of carbon dioxide transport and interface stability heavily affected by presence of calcite and temperature. CO2 molecules are able to cross both aqueous layers. At low temperatures, CO2 molecules assumed positions at the centers of the partial hydrate cavities. These CO2 molecules tended to remain trapped and behaved very similar to the bulk hydrate CO2 guest molecules. The neighboring free water molecules formed hydrate-like hydrogen bonded structures. At all simulations temperatures, many CO2 molecules were adsorbed on calcite surface. The calcite adsorption rate of CO2 molecules increased with the temperature. When the molecules come close to the calcite surface, a single CO2 molecule is adsorbed onto a calcium ion so as to maximize the electrostatic attraction. These calcium-CO2 pairs are very stable and will permanently remove CO2 from solution thus enhancing the efficiency of CO2 storage in geological formations for carbon emission mitigation and enhanced oil recovery.
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Analysis of Pressure Versus Flow Regime of CO2 To Assess Matrix and Fracture Injection at In Salah, Algeria
Authors B. Bohloli, E. Aker, F. Cuisiat, V. Oye and D. KühnThis paper presents an analysis of CO2 injection history for three wells drilled into the water leg of the Krechba reservoir, In Salah, Algeria. The hydro-mechanical behaviour of CO2 storage is reflected in the injection history of wells. Detailed analysis of pressure versus flow rate was carried out to differentiate between periods of matrix and fracture injection and assess optimum injection pressure. The history clearly shows periods of CO2 injection into the reservoir (and possibly surrounding rocks) under fracturing conditions, thus providing the formation fracturing pressure and maximum matrix flow rate. The maximum applied pressure in all three wells has likely exceeded the fracturing pressure of the reservoir at various periods since project start-up. The findings are supported by other sets of data such as in-situ stress profile, empirically calculated fracturing pressure, FIT, LOT and microseismic events.
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