Geological Storage Of Carbon Dioxide Research Articles

Clay Hydration/dehydration in Dry to Water-saturated Supercritical CO2: Implications for Caprock Integrity

Injection of supercritical CO2 (scCO2) for the geologic storage of carbon dioxide will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water- saturated scCO2. Wet scCO2 is highly reactive and capable of carbonating and hydrating certain minerals, whereas anhydrous scCO2 can dehydrate water-containing minerals. Because these geochemical processes affect solid volume and thus porosity and permeability, they have the potential to affect the long-term integrity of the caprock seal. In this study, we investigate the swelling and shrinkage of an expandable clay found in caprock formations, montmorillonite (Ca-STx-1), when exposed to variable water-content scCO2 at 50°C and 90bar using a combination of in situ probes, including X-ray diffraction (XRD), in situ magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), and in situ attenuated total reflection infrared spectroscopy (ATR-IR). We show that the extent of montmorillonite clay swelling/shrinkage is dependent not only on water hydration/dehydration, but also on CO2 intercalation reactions. Our results also suggest a competition between water and CO2 for interlayer residency where increasing concentrations of intercalated water lead to decreasing concentrations of intercalated CO2. Overall, this paper demonstrates the types of measurements required to develop fundamental knowledge that will enhance modeling efforts and reduce risks associated with subsurface storage of CO2.

Improvement of CO2 Geological Storage Efficiency by Injection and Production Well Design

In carbon dioxide (CO2) geological storage projects, to improve storage safety while keeping costs low is of primary importance. Several methods have been proposed to treat this issue. In this study, to get insight into the effectiveness of the rotating injection of CO2 and re-injection of the brine, simple simulations were carried out using TOUGH2 numerical simulator implemented with additional source code to account for the effect relative permeability hysteresis.Results indicate that the rotating injection increases the trapped ratio of CO2. Frequent injection increases the total amount of CO2 injected with rotating injection, but it does not necessarily increase the trapped amount of CO2. Brine injection and production results in more CO2 trapped than with rotating injection. Trapped ratio was increased by about 20% from base case. It is concluded that design of CO2 injection and brine production/injection is an effective method to improve efficiency of CO2 storage projects.

CO2 Sequestration Potential of Unmineable Coal—State of Knowledge

Currently the U.S. Geological Survey (USGS) national assessment of geological carbon dioxide (CO2) storage resource considers porous sandstones, limestones, and dolomites as potential storage formations. Assessment of an additional potential geologic storage resource within unmineable coal seams was deferred because no consensus exists on what constitutes unmineable coal. Because unmineable coal seams may be considered potential storage resources in future assessments, however, the USGS is researching factors affecting CO2 storage potential in coal.

Depositional Environment as an Indicator of Favorable Regional Sequestration Targets: Examples from the USGS CO2 Storage Resource Assessment

An analysis of the of sealing formations chosen as cap rocks in the U.S. Geological Survey (USGS) geologic carbon dioxide (CO2) storage resource assessment reveals certain depositional environments that produce suitable regional scale sequestration seals. The USGS methodology requires low permeability, regional, and homogenous seals of approximately 30 meters thickness for shales and 6 meters thickness for evaporites. Open-shelf marine slope and basin shales, as well as shallow water evaporitic deposits make up a majority of storage formation seals identified in the assessment that meet this criteria. Since adequate cap rock is the limiting component of the reservoir and seal couplet required to sequester CO2, these specific depositional environments are recommended as initial targets for regional-scale sequestration assessments and research.

Reducing Uncertainty in Reservoir Model Predictions: from Plume Evolution to Tool Responses

With the transition of geological carbon dioxide (CO2) storage from pilot to industrial scale, risk analysis has become pivotal for assessing the suitability of a storage site in satisfying regulatory requirements during and after injection. Risk analysis is inherently related to uncertainty quantification. This paper extends our previously developed workflows to quantify and propagate uncertainty from geological, geophysical and petrophysical data to project-level performance metrics including capacity, injectivity, and containment characteristics. We perform global sensitivity analysis to quantitatively link uncertainty in the computed performance metrics to the uncertainties in the underlying reservoir parameters. This enables one to identify measurements to reduce uncertainty estimates of reservoir performance metrics and predicted monitoring tool responses. We illustrate this workflow in a pre-injection uncertainty study for the Illinois Basin Decatur Project (IBDP). The reservoir model is built using geostatistical approach based on all available geophysical and petrophysical data including 3D seismic interpretation, results of special core analysis and injectivity tests. We focus on three groups of performance predictions: spatial extent of the CO2 saturation profile, partitioning of CO2, and predicted responses seen with the Westbay* multilevel groundwater characterization and monitoring system installed in the monitoring well. Based on multiple realizations of the reservoir model we evaluate the uncertainty range in pressures and CO2 saturations at the Westbay monitoring zones during the life of the project. Predicted measurements at the monitoring zones covering a depth interval between 1950 m and 2120 m are analyzed. Global sensitivity analysis is used to identify the key petrophysical properties of the reservoir whose uncertainties have the most effect on the uncertainty of the reservoir performance and measurement predictions. Results of this analysis provide valuable insight for targeted site characterization and design of the monitoring program.

Mineral Migration and Regeneration Reactions in the Two Phase Flow Experiment

Scientists look forward to developing of emerging carbon oxide reduction technology which by artificial injection methods of industrial carbon dioxide geological storage in deep saline aquifers or geological structures, and then inhibit carbon dioxide accumulated in the atmosphere or prevent generation of the greenhouse effect. In this case, by using core flooding test for simulation the physical properties of the two-phase fluid flow (saline and carbon dioxide) in deep saline aquifers, the loss of mineral composition and regeneration reactions can be understood. In the initial experiments, we used Berea sandstone for core flooding test. In addition, the specimen was detected by X-ray diffraction and Scanning Electron Microscopy (SEM) analysis during the period before and after the test, to understand whether mineral crystal phase and microstructure changes had been occurred. After the core flooding test, the specimens were detected by energy spectrum of elements and elemental distribution analysis, and the main elements were oxygen and silicon.

Оценка возможностей захоронения углекислого газа в геологических резервуарах

Оценка возможностей захоронения углекислого газа в геологических резервуарах

PVTX Properties of H2O-CO2-"salt" at PTX Conditions Applicable to Carbon Sequestration in Saline Formations

Among the many scenarios that have been proposed to reduce the amount of carbon dioxide (CO2) emissions to the atmosphere, carbon-capture and storage (CCS) in geological reservoirs represents the method most technologically feasible and capable of accommodating the large amounts of CO2 that are generated on an annual basis by combustion of fossil fuels (IPCC, 2005). Geological environments and processes that have been proposed for CCS include deep, unmineable coal seams, depleted oil and gas reservoirs, organic-rich shale basins, deep saline formations, and mineral carbonation of basalts. Of these various options, the one that is most attractive owing to its widespread distribution and capacity to store large amounts of CO2 is deep saline formations, with the U.S. Department of Energy reporting that saline formations in the United States could potentially store more than 2,100–20,000 billion metric tons of CO2 (DOE, 2012). A recently released assessment of geologic carbon dioxide storage potential (USGS, 2013) estimates a capacity ranging from 2,400 to 3,700 billion metric tonnes (Gt) of CO2, which corresponds to the low end of the DOE estimate. When supercritical CO2 (scCO2) is injected into a saline formation, it may be stored in various ways. Initially, the CO2 will be stored by structural and stratigraphic trapping, whereby scCO2 is trapped beneath an impermeable confining layer that prohibits the upward migration of the more buoyant scCO2. Some scCO2 may also be stored by residual trapping in pores via capillary forces. In the discussion to follow, we include residual trapping with structural/stratigraphic trapping as all of these processes involve the storage of a scCO2 phase and, as such, the volume requirements are assumed to be identical for these storage mechanisms for a given mass of CO2. Over time, …

High-performance Supercomputing as a Risk Evaluation Tool for Geologic Carbon Dioxide Storage

Numerical modelling is a vital tool for predicting the behavior and fate of CO2 in reservoirs as well as its impacts on subsurface environments. Recently, powerful numerical codes that are capable of solving coupled complex processes of physics and chemistry required for such modeling works have been developed. However they are often computationally demanding for solving the complex non-linear models in sufficient spatial and temporal resolutions. Geological heterogeneity and uncertainties further increase the challenges in modeling work, because they may necessitate stochastic modeling with multiple realizations. There is clearly a need for high-performance computing. In this study, we implemented TOUGH2-MP code (a parallel version of multi-phase flow simulator TOUGH2) on two different types (vector- and scalar-type) of world-class supercomputers with tens of thousands of processors in Japan. The parallelized code generally exhibited excellent performance and scalability after adequate tune-ups of the code. Using the code and the supercomputers, we have been performed several computationally demanding simulations. In this paper, we present the performances of parallel computation of the code measured on the two supercomputers. Then the following two examples are presented: 1) a highly heterogeneous high-resolution model, representing irregular nature of sand/shale distribution; 2) “Dissolution Diffusion Convection Process”, which is expected to significantly enhance the dissolution trapping. Through the above two examples, it is illustrated that the spatial resolution of numerical model can critically change the evaluation of the effectiveness of CO2 trapping mechanisms, demonstrating the necessity of supercomputing techniques for evaluating these risks more accurately.

U.S. Geological Survey Geologic Carbon Dioxide Storage Resource Assessment of the United States

The U.S. Geological Survey (USGS) is conducting geology-based carbon dioxide storage resource evaluations of approximately 40 major sedimentary basins in the United States in order to fulfill some of the requirements of the Energy Independence and Security Act of 2007. Individual storage assessment units (SAUs) within each basin are defined on the basis of geologic and hydrologic characteristics. Summary geologic descriptions of the evaluated basins and SAUs will be published, along with the results of the national assessment and related research.

Experimental and molecular modelling study of the three-phase behaviour of (propane + carbon dioxide + water) at reservoir conditions

Acquiring a comprehensive understanding of the phase behaviour of mixtures of crude-oil with carbon dioxide and water is a key input for reservoir engineering in processes of enhanced oil recovery and geological storage of carbon dioxide. To gain an insight, given the very complex nature of crude-oil mixtures, the study of simpler systems is of interest. In this work the system (propane+carbon dioxide+water) has been chosen as a model (light oil fraction+carbon dioxide+water) mixture. Phase equilibrium measurements have been carried out using a quasi-static-analytical high-pressure apparatus that was validated on the system (n-decane+carbon dioxide) in comparison with literature data, and used to study the system (n-decane+carbon dioxide+water) [E. Forte, A. Galindo, J. P.M. Trusler, The Journal of Physical Chemistry B 115 (49) (2011) 14591–14609]. In the present work, new experimental data have been measured for the system (propane+carbon dioxide+water) under conditions of three-phase equilibria. Compositions of the three coexisting phases have been obtained along four isotherms at temperatures from 311 to 353K and at pressures up to the upper critical end points where the propane-rich and the carbon dioxide-rich phases become critical. The experimental data obtained for the ternary mixture have been compared to the predictions obtained with the statistical associating fluid theory for potentials of variable range (SAFT-VR). The phase behaviour of each pair of binary subsystems has been calculated using this theory and, where applicable, a modification of the Hudson and McCoubrey combining rules has been used to treat the systems predictively. Furthermore, a detailed analysis of the phase behaviour of the ternary mixture has been carried out based on comparison with available data for the constituent binary subsystems, as well as with the previous findings for the ternary (n-decane+carbon dioxide+water). Such comparison is useful to examine the effect that adding a third component has in the mutual solubility of each pair. Remarks relevant to reservoir processing are also highlighted.

Monitoring freshwater salinization in analog transport models by time-lapse electrical resistivity tomography

Abstract Deep saline aquifers are target formations both for the geological storage of carbon dioxide as well as for geothermal applications. High pressure gradients, resulting from fluid or gas injection processes, provide a potential driving force for the displacement of native formation waters, implicating a potential salinization of shallow freshwater resources. Geoelectrical monitoring techniques are sensitive to compositional changes of groundwater resources, and hence capable to detect salinization processes at an early stage. In this context, numerical simulations and analog modeling can provide a valuable contribution by identifying probable salinization scenarios, and thereby guiding an optimum sensor network layout within the scope of an early warning system. In this study, coupled numerical flow and transport simulations of a laterally uniform salinization scenario were carried out and used to support a subsequent realization in a laboratory sandbox model. During the experiment, electrical resistivity tomography (ERT) was applied in a practical surface–borehole setup in order to determine the spatio-temporal variations of electrical properties influenced by saltwater intrusion. Inversion results of different electrode configurations were evaluated and compared to numerical simulations. With regard to surface–borehole measurements, good results were obtained using crossed bipoles, while regular bipole measurements were more susceptible to noise. Within the scope of a single-hole tomography, the underlying resistivity distribution was best reproduced using the Wenner configuration, which was substantiated by synthetic modeling.

Geological Storage of Carbon Dioxide in Coal Seam is Effective Method for Environment Protection and Energy Sustainable Development in China

The reduction of greenhouse gases emission is a growing concern of many countries. The geological storage of is useful and effective approaches to reduce emission. The oil and natural gas industries have long commercial practice of gas injection, enhanced oil recovery ( -EOR). Because coal seam has strong absorption capacity for ,the coal seam can be used as geological storage reservoirs, and coal seam has such characteristics that coal seam is preference for absorption and postponement for absorption, injection into coal seam can enhanced coal bed methane recovery, -ECBM, is a new energy generated by methane from injection into coal seam, and is beneficial complement of the energy , injection into coal seam can not only reduce greenhouse gases emission and but also enhance coal bed methane recovery, which is very significance to environment protection and energy sustainable development in china.

Briefing: New life for old coal

Coal-fired power plants still have a sizeable ‘carbon footprint’, despite advances in technology that have made them ‘greener’. On the other hand, many of the world’s coal reserves are also lying unused because the seams are simply too deep to dig out. Researchers at the University of Leeds, together with leading Institutions from Bulgaria, Germany, Greece and Portugal, hope to solve these problems by exploring a greener, safer and cheaper way of using coal from deep underground seams as an energy source in a €3 million project funded by the Research Fund for Coal and Steel of the European Commission. Under the proposed underground coal gasification scheme, coal would be gasified underground to generate combustible gases, offering a new lease of life to coal seams that are too expensive to mine. The depth is sufficient for underground coal gasification to be combined with carbon dioxide capture and geological storage in the dense phase to fulfil the objectives of ‘low-carbon’ energy supply and energy security envisaged in the 2007 UK Energy white paper, Meeting the Energy Challenge.

CO2 storage capacity assessment of deep saline aquifers in the Subei Basin, East China

Geological storage of carbon dioxide (CO2) is one of the most critical technologies in reducing anthropogenic and fossil fuel emissions to the atmosphere. The most critical scientific problem has been the selection of storage site for long-term safety, as well as reliable and reasonable estimation of CO2 storage capacity. This paper analyzed the stability effect factors in identifying the most suitable reservoir-seal assemblages in the Subei Basin in China. In this area, the Lower Yancheng Formation and the Upper Sanduo Formation were selected accurately based on analysis of their geomorphological and geological characteristics. Considering simultaneously the different tectonic units, cap-rock conditions, hydrodynamic conditions, and other factors, these formations could function as optimal reservoirs. The storage capacity in the aquifer layers hosted by these formations was estimated. The results showed that, on average, the storage capacity of the Lower Yancheng Formation is approximately 21.788×108t, whereas that of the Upper Sanduo Formation is approximately 45.866×108t. For the first-order tectonic units, the total storage capacity of the aforementioned two reservoir formations in the Yanfu Depression and the Dongtai Depression reaches 11.01×108 and 56.644×108t, respectively, at the basin scale.

Ganglion Dynamics and Its Implications to Geologic Carbon Dioxide Storage

Capillary trapping of a nonwetting fluid phase in the subsurface has been considered as an important mechanism for geologic storage of carbon dioxide (CO(2)). This mechanism can potentially relax stringent requirements for the integrity of cap rocks for CO(2) storage and therefore can significantly enhance storage capacity and security. We here apply ganglion dynamics to understand the capillary trapping of supercritical CO(2) (scCO(2)) under relevant reservoir conditions. We show that, by breaking the injected scCO(2) into small disconnected ganglia, the efficiency of capillary trapping can be greatly enhanced, because the mobility of a ganglion is inversely dependent on its size. Supercritical CO(2) ganglia can be engineered by promoting CO(2)-water interface instability during immiscible displacement, and their size distribution can be controlled by injection mode (e.g., water-alternating-gas) and rate. We also show that a large mobile ganglion can potentially break into smaller ganglia due to CO(2)-brine interface instability during buoyant rise, thus becoming less mobile. The mobility of scCO(2) in the subsurface is therefore self-limited. Vertical structural heterogeneity within a reservoir can inhibit the buoyant rise of scCO(2) ganglia. The dynamics of scCO(2) ganglia described here provides a new perspective for the security and monitoring of subsurface CO(2) storage.

Spatial grid correction for short-term numerical simulation results of carbon dioxide dissolution in saline aquifers

Numerical simulation is an essential component of many studies of geological storage of carbon dioxide, but care must be taken to ensure the accuracy of the results. Unlike several other possible sources of simulation errors, which have previously been considered in detail and have well-understood techniques for mitigating their effects, comparatively little discussion of the spatial grid dependence of the dissolution rate of carbon dioxide into the formation water has appeared in the literature, despite its importance to simulation studies of geological storage of carbon dioxide in saline aquifers. In many instances, sufficient refinement of the computational grid can be a practical solution. However, this approach is not always feasible, especially for large-scale simulations in three dimensions requiring multiple realisations, which commonly feature a coarse grid due to constraints on available computational capabilities. A measure of the error in the amount of dissolved carbon dioxide introduced by the use of a finite grid is therefore of great interest. In this study, the use of finite-sized grid blocks is shown to overestimate the amount of dissolved carbon dioxide in short-term results by a factor of 1 + Vf/Vp, where Vf is the grid block volume at the saturation front and Vp is the total grid block volume of the plume. This result can be used in a number of ways to correct the calculated short-term dissolution in coarse-scale simulations so that the amount dissolved agrees better with that obtained from fine-scale simulations.

Effects of a capillary transition zone on the stability of a diffusive boundary layer

In geological storage of carbon dioxide (CO2), the buoyant CO2 plume eventually accumulates under the caprock. Due to interfacial tension between the CO2 phase and the water phase, a capillary transition zone develops in the plume. This zone contains supercritical CO2 as well as water with dissolved CO2. Under the plume, a diffusive boundary layer forms. We study how cross-flow between the capillary transition zone and the diffusive boundary layer affects gravitational stability of the diffusive boundary layer. Linear stability analysis shows that this cross-flow has no significant effect on the selection of the critical mode. However, interaction with the capillary transition zone enhances the instability of the boundary layer, such that the onset of instabilities occurs earlier, when the diffusive boundary layer is thinner. The onset time may be reduced by a factor of five, which corresponds to the thickness of the diffusive boundary layer at onset being reduced by a factor of two. This reduced thickness of the boundary layer at onset can be interpreted in terms of a reduced portion of the critical mode that must ’fit’ inside the boundary layer when the other portion of the mode is confined within the capillary transition zone. Direct numerical simulations for the non-linear regime show that the mass transfer rate can be enhanced up to four times when the cross-flow is accounted for. This increase is related to advective inflow of CO2-saturated water across the interface. Therefore, the contribution from dissolution to the safety of geological storage of CO2 begins earlier and can be considerably larger than showed by estimates that neglect the capillary transition zone.

Prospects for underground coal gasification in Alberta, Canada

Coal-bearing formations underlie approximately 303 000 km2 of Alberta. Coal seams can be traced in the subsurface, in hundreds of thousands of boreholes, over tens of kilometres and coal zones over hundreds of kilometres. Alberta has 2000 Gt of coal resource containing more than three times the energy content of Alberta’s oil sands (in-place bitumen resources at 1·8 trillion barrels); however, much of the coal is too deep or too costly to mine and it appeared that most of this vast resource would never be exploited. Underground coal gasification (UCG) linked to various carbon dioxide capture and geological storage technologies offers a way that Alberta’s coal resources can be utilised in a ‘carbon constrained’ world. With coal having been gasified at depths up to 1400 m, in an Albertan UCG pilot project, the huge coal endowment can be recognised as a potential answer for North America’s energy demand.

Earthquake triggering and large-scale geologic storage of carbon dioxide

Despite its enormous cost, large-scale carbon capture and storage (CCS) is considered a viable strategy for significantly reducing CO(2) emissions associated with coal-based electrical power generation and other industrial sources of CO(2) [Intergovernmental Panel on Climate Change (2005) IPCC Special Report on Carbon Dioxide Capture and Storage. Prepared by Working Group III of the Intergovernmental Panel on Climate Change, eds Metz B, et al. (Cambridge Univ Press, Cambridge, UK); Szulczewski ML, et al. (2012) Proc Natl Acad Sci USA 109:5185-5189]. We argue here that there is a high probability that earthquakes will be triggered by injection of large volumes of CO(2) into the brittle rocks commonly found in continental interiors. Because even small- to moderate-sized earthquakes threaten the seal integrity of CO(2) repositories, in this context, large-scale CCS is a risky, and likely unsuccessful, strategy for significantly reducing greenhouse gas emissions.