共查询到20条相似文献,搜索用时 15 毫秒
1.
Hannah E. Ross Paul Hagin Mark D. Zoback 《International Journal of Greenhouse Gas Control》2009,3(6):773-786
Coalbeds are an attractive geological environment for storage of carbon dioxide (CO2) because CO2 is retained in the coal as an adsorbed phase and the cost of injection can be offset by enhanced coalbed methane (ECBM) production. This paper presents the findings of a CO2 storage feasibility study on coalbeds in the Wyodak-Anderson coal zone of the Powder River Basin, Wyoming, USA, using reservoir characterization and fluid flow simulations. A 3D numerical model of the Big George coal was constructed using geostatistical techniques, with values of cleat and matrix permeability and porosity constrained through history-matching of production data from coalbed methane (CBM) wells in the field area.Following history-matching, several ECBM and CO2 storage scenarios were investigated: shrinkage and swelling of the coal was either allowed or disallowed, a horizontal hydraulic fracture was either placed at the injection well or removed from the model, the number of model layers was varied between 1 and 24, and the permeability and porosity fields were constructed to be either homogeneous or heterogeneous in accordance with geostatistical models of regional variability. All simulations assumed that the injected gas was 100% CO2 and that the coalbed was overlain by an impermeable caprock. Depending on the scenario, the simulations predicted that after 13 years of CO2 injection, the cumulative methane production would be enhanced by a factor of 1.5–5. Including coal matrix shrinkage and swelling in the model predicted swelling near the injection well, which resulted in a slight reduction (10%) in injection rate. However, including a horizontal hydraulic fracture in the model at the base of the injection well helped mitigate the negative effect of swelling on injection rate. It was also found that six model layers were needed to have sufficient resolution in the vertical direction to account for the buoyancy effects between the gas and resident water, and that capturing the heterogeneous nature of the coal permeability and porosity fields predicted lower estimates of the storage capacity of the Wyodak-Anderson coal zone.After noting that gravity and buoyancy were the major driving forces behind gas flow within the Big George coal, several leakage scenarios were also investigated, in an effort to better understand the interplay between diffusion and flow properties on the transport and storage of CO2. The modeling predicted that the upward migration of gas due to the buoyancy effect was faster than the diffusion of CO2 and therefore the gas rapidly rose to the top of the coalbed and migrated into overlying strata when an impermeable caprock was not included in the model. 相似文献
2.
Andrew C. Mitchell Adrienne J. Phillips Randy Hiebert Robin Gerlach Lee H. Spangler Alfred B. Cunningham 《International Journal of Greenhouse Gas Control》2009,3(1):90-99
In order to develop subsurface CO2 storage as a viable engineered mechanism to reduce the emission of CO2 into the atmosphere, any potential leakage of injected supercritical CO2 (SC-CO2) from the deep subsurface to the atmosphere must be reduced. Here, we investigate the utility of biofilms, which are microorganism assemblages firmly attached to a surface, as a means of reducing the permeability of deep subsurface porous geological matrices under high pressure and in the presence of SC-CO2, using a unique high pressure (8.9 MPa), moderate temperature (32 °C) flow reactor containing 40 millidarcy Berea sandstone cores. The flow reactor containing the sandstone core was inoculated with the biofilm forming organism Shewanella fridgidimarina. Electron microscopy of the rock core revealed substantial biofilm growth and accumulation under high-pressure conditions in the rock pore space which caused >95% reduction in core permeability. Permeability increased only slightly in response to SC-CO2 challenges of up to 71 h and starvation for up to 363 h in length. Viable population assays of microorganisms in the effluent indicated survival of the cells following SC-CO2 challenges and starvation, although S. fridgidimarina was succeeded by Bacillus mojavensis and Citrobacter sp. which were native in the core. These observations suggest that engineered biofilm barriers may be used to enhance the geologic sequestration of atmospheric CO2. 相似文献
3.
Coal combustion by-products such as fly ash (FA), brine and CO(2) from coal fired power plants have the potential to impact negatively on the environment. FA and brine can contaminate the soil, surface and ground water through leaching of toxic elements present in their matrices while CO(2) has been identified as a green house gas that contributes significantly towards the global warming effect. Reaction of CO(2) with FA/brine slurry can potentially provide a viable route for CO(2) sequestration via formation of mineral carbonates. Fractionated FA has varying amounts of CaO which not only increases the brine pH but can also be converted into an environmentally benign calcite. Carbonation efficiency of fractionated and brine impacted FA was investigated in this study. Controlled carbonation reactions were carried out in a reactor set-up to evaluate the effect of fractionation on the carbonation efficiency of FA. Chemical and mineralogical characteristics of fresh and carbonated ash were evaluated using XRF, SEM, and XRD. Brine effluents were characterized using ICP-MS and IC. A factorial experimental approach was employed in testing the variables. The 20-150 μm size fraction was observed to have the highest CO(2) sequestration potential of 71.84 kg of CO(2) per ton of FA while the >150 μm particles had the lowest potential of 36.47 kg of CO(2) per ton of FA. Carbonation using brine resulted in higher degree of calcite formation compared to the ultra-pure water carbonated residues. 相似文献
4.
《International Journal of Greenhouse Gas Control》2007,1(2):215-222
This paper describes the results of a single well micro-pilot test performed at an existing well in the anthracitic coals of the South Qinshui basin, Shanxi Province, China. A set of reservoir parameters was obtained from the micro-pilot test. The field data was successfully history matched using a tuned reservoir model which accounted for changes in permeability due to swelling and pressure change. Prediction of initial performance showed significant production enhancement of coalbed methane while simultaneously storing the CO2. The calibrated reservoir model was used to design a multi-well pilot at the site to validate the performance prediction. The design is now completed. The recommendation is to proceed to the next stage of multi-well pilot testing and to demonstrate the enhanced coalbed methane (ECBM) technology. 相似文献
5.
Yoshio Masuda Yasuhiro Yamanaka Yoshikazu Sasai Michimasa Magi Takashi Ohsumi 《International Journal of Greenhouse Gas Control》2009,3(1):67-76
Site selection in CO2 ocean sequestration is examined based on the idea that a site where injected CO2 is efficiently diluted is favourable in reducing/avoiding biological impacts. Simulations of CO2 injection into several sites by an eddy-resolving oceanic general circulation model (OGCM) show that the maximum CO2 concentration differs by a factor of 10 among sites. The distribution of eddy activity is the most important causative factor producing the geographical differences in CO2 dilution. Based on the relationship between the maximum CO2 concentration and eddy activity, we estimated the distribution of the maximum CO2 injection rate by a proposed method, which does not cause chronic impacts on biota. Around Japan, extensive ocean volume has the potential to dilute 20 million tonnes per year without chronic impacts, and some areas can be injected with 80 million tonnes per year. 相似文献
6.
In the Republic of Estonia, local low-grade carbonaceous fossil fuel--Estonian oil-shale--is used as a primary energy source. Combustion of oil-shale is characterized by a high specific carbon emission factor (CEF). In Estonia, the power sector is the largest CO(2) emitter and is also a source of huge amounts of waste ash. Oil-shale has been burned by pulverized firing (PF) since 1959 and in circulating fluidized-bed combustors (CFBCs) since 2004-2005. Depending on the combustion technology, the ash contains a total of up to 30% free Ca-Mg oxides. In consequence, some amount of emitted CO(2) is bound by alkaline transportation water and by the ash during hydraulic transportation and open-air deposition. The goal of this study was to investigate the possibility of improving the extent of CO(2) capture using additional chemical and technological means, in particular the treatment of aqueous ash suspensions with model flue gases containing 10-15% CO(2). The results indicated that both types of ash (PF and CFBC) could be used as sorbents for CO(2) mineral sequestration. The amount of CO(2) captured averaged 60-65% of the carbonaceous CO(2) and 10-11% of the total CO(2) emissions. 相似文献
7.
Mark Person Amlan Banerjee John Rupp Cristian Medina Peter Lichtner Carl Gable Rajesh Pawar Michael Celia Jennifer McIntosh Victor Bense 《International Journal of Greenhouse Gas Control》2010,4(5):840-854
Idealized, basin-scale sharp-interface models of CO2 injection were constructed for the Illinois basin. Porosity and permeability were decreased with depth within the Mount Simon Formation. Eau Claire confining unit porosity and permeability were kept fixed. We used 726 injection wells located near 42 power plants to deliver 80 million metric tons of CO2/year. After 100 years of continuous injection, deviatoric fluid pressures varied between 5.6 and 18 MPa across central and southern part of the Illinois basin. Maximum deviatoric pressure reached about 50% of lithostatic levels to the south. The pressure disturbance (>0.03 MPa) propagated 10–25 km away from the injection wells resulting in significant well–well pressure interference. These findings are consistent with single-phase analytical solutions of injection. The radial footprint of the CO2 plume at each well was only 0.5–2 km after 100 years of injection. Net lateral brine displacement was insignificant due to increasing radial distance from injection well and leakage across the Eau Claire confining unit. On geologic time scales CO2 would migrate northward at a rate of about 6 m/1000 years. Because of paleo-seismic events in this region (M5.5–M7.5), care should be taken to avoid high pore pressures in the southern Illinois basin. 相似文献
8.
Roland T. Okwen Mark T. Stewart Jeffrey A. Cunningham 《International Journal of Greenhouse Gas Control》2010,4(1):102-107
During injection of carbon dioxide (CO2) into deep saline aquifers, the available pore volume of the aquifer may be used inefficiently, thereby decreasing the effective capacity of the repository for CO2 storage. Storage efficiency is the fraction of the available pore space that is utilized for CO2 storage, or, in other words, it is the ratio between the volume of stored CO2 and the maximum available pore volume. In this note, we derive and present simple analytical expressions for estimating CO2 storage efficiency under the scenario of a constant-rate injection of CO2 into a confined, homogeneous, isotropic, saline aquifer. The expressions for storage efficiency are derived from models developed previously by other researchers describing the shape of the CO2-brine interface. The storage efficiency of CO2 is found to depend on three dimensionless groups, namely: (1) the residual saturation of brine after displacement by CO2; (2) the ratio of CO2 mobility to brine mobility; (3) a dimensionless group (which we call a “gravity factor”) that quantifies the importance of CO2 buoyancy relative to CO2 injection rate. In the particular case of negligible residual brine saturation and negligible buoyancy effects, the storage efficiency is approximately equal to the ratio of the CO2 viscosity to the brine viscosity. Storage efficiency decreases as the gravity factor increases, because the buoyancy of the CO2 causes it to occupy a thin layer at the top of the confined formation, while leaving the lower part of the aquifer under-utilized. Estimates of storage efficiency from our simple analytical expressions are in reasonable agreement with values calculated from simulations performed with more complicated multi-phase-flow simulation software. Therefore, we suggest that the analytical expressions presented herein could be used as a simple and rapid tool to screen the technical or economic feasibility of a proposed CO2 injection scenario. 相似文献
9.
《International Journal of Greenhouse Gas Control》2007,1(1):11-18
Vacuum swing adsorptive (VSA) capture of CO2 from flue gas and related process streams is a promising technology for greenhouse gas mitigation. Although early reports suggested that VSA was problematic and expensive, through the application of more logical process configurations that are appropriately coupled to the composition of the feed and product gas streams, we can now refute this early assertion. Improved cycle designs coupled with tighter temperature control are also helping to optimise performance for CO2 separation. Simultaneously, new adsorbent materials are being developed. These separate CO2 by selective (acid-base) reaction with surface bound amine groups (chemisorption), rather than on the basis of non-bonding interactions (physisorption). This report describes some of these recent developments from our own laboratories and points to synergies that are anticipated as a result of combining these improvements in adsorbent properties and VSA process cycles. 相似文献
10.
Katherine T. Schwarz Tad W. Patzek Dmitriy B. Silin 《International Journal of Greenhouse Gas Control》2009,3(4):422-430
The concentration of CO2 in air near the ground needs to be predicted to assess environmental and health risks from leaking underground storage. There is an exact solution to the advection–diffusion equation describing trace gases carried by wind when the wind profile is modeled with a power-law dependence on height. The analytical solution is compared with a numerical simulation of the coupled air–ground system with a source of CO2 underground at the water table. The two methods produce similar results far from the boundaries, but the boundary conditions have a strong effect; the simulation imposes boundary conditions at the edge of a finite domain while the analytic solution imposes them at infinity. The reverse seepage from air to ground is shown in the simulation to be very small, and the large difference between time scales suggests that air and ground can be modeled separately, with gas emissions from the ground model used as inputs to the air model. 相似文献
11.
Yu Wu Jishan Liu Derek Elsworth Zhongwei Chen Luke Connell Zhejun Pan 《International Journal of Greenhouse Gas Control》2010,4(4):668-678
Although the influence of gas sorption-induced coal deformation on porosity and permeability has been widely recognized, prior studies are all under conditions of no change in overburden stress and effective stress-absent where effective stresses scale inversely with applied pore pressures. Here we extend formalism to couple the transport and sorption of a compressible fluid within a dual-porosity medium where the effects of deformation are rigorously accommodated. This relaxes the prior assumption that total stresses remain constant and allows exploration of the full range of mechanical boundary conditions from invariant stress to restrained displacement. Evolution laws for permeability and related porosity are defined at the micro-scale and applied to both matrix and an assumed orthogonal, regular and continuous fracture system. Permeability and porosity respond to changes in effective stress where sorption-induced strains may build total stresses and elevate effective stresses. Gas accumulation occurs in both free- and adsorbed-phases and due to effective grain and skeletal compressibilities. A finite element model is applied to quantify the net change in permeability, the gas flow, and the resultant deformation in a prototypical coal seam under in situ stresses. Results illustrate how the CO2 injectivity is controlled both by the competition between the effective stress and the gas transport induced volume change within the matrix system and by the dynamic interaction between the matrix system and the fracture system. For typical parameters, initial injection-related increases in permeability due to reduced effective stresses may endure for days to years but are ultimately countered by long-term reductions in permeability which may decline by an order of magnitude. Models suggest the crucial role of stresses and the dynamic interaction between matrix and fractures in correctly conditioning the observed response. 相似文献
12.
To provide more efficient utilization of village wastes and agricultural residues and eliminate pollution from current practices anaerobic treatment of such wastes with methane recovery is proposed. This paper describes studies to determine the performance of anaerobic composting for such wastes.Composting of three waste types was investigated: (a) agricultural residues, (b) Village solid waste and 1:1 mixture of (a) and (b). Three 150 gallon reactors with periodic leachate recycling were used for anaerobic composting while three 50 gallon reactors produced an aerobic compost from the same wastes. Reactors were maintained for six months simulating the time between growing seasons. Volatile solids destruction ranged from 10.3 to 38.7%. Biogas production was ranged from 1350 to 1420 1 per k of volatile solids destroyed with a methane content of 55 to 70%. Leachate was monitored throughout for: pH, alkalinity, total and ammonia nitrogen, COD, TOC, total solids, volatile solids and four metals. MPN data was collected for various bacterial groups (total plate count, anaerobic cellulose decomposers, and anaerobic acid producers) to monitor increases and declines in the leachate bacterial population. Physical and chemical testing provided comparisons between finished anaerobic compost and aerobic compost from the same three waste samples. 相似文献
13.
A.A.A. Solieman J.W. Dijkstra W.G. Haije P.D. Cobden R.W. van den Brink 《International Journal of Greenhouse Gas Control》2009,3(4):393-400
Calcium oxide (CaO) is a material that is being widely investigated in the context of CO2 capture. One such application is as a CO2 sorbent in the sorption-enhanced steam methane reforming processes (SERP). CO2 is captured in an adsorption mode, where the conversion of CH4 to H2 is also enhanced, and released later in a separate desorption mode. This work presents an analysis of the relation between different process conditions and parameters during both adsorption and desorption modes. The interrelation between these conditions and the sorbent properties as well as the targeted carbon capture ratio is analysed. Conditions relevant for capturing 85% of carbon in the feed on CaO are determined and interlinked. A steam-to-carbon ratio of 4.2 has been determined to be relevant under 600 °C and 17 bar adsorption conditions. Similarly, process conditions relevant for regenerating the sorbent are determined and interlinked. For purge steam-to-CO2 ratio of 1.8 at a desorption pressure of 1 bar, relevant desorption temperature has been calculated to be 820 °C. System simulations under these adsorption and desorption conditions resulted in a system efficiency of 50.8%. Effect of tuning process operating conditions on system efficiency as well as the efficiency penalty associated with the regeneration of the sorbent are investigated by process simulations using Aspen Plus®. Possible system heat integration routes to reduce the efficiency penalty are proposed and the results of the process simulations are presented. 相似文献
14.
H.A.J. van Dijk S. Walspurger P.D. Cobden R.W. van den Brink F.G. de Vos 《International Journal of Greenhouse Gas Control》2011,5(3):505-511
The feasibility of the sorption enhanced water gas shift (SEWGS) process under sour conditions is shown. The sour-SEWGS process constitutes a second generation pre-combustion carbon capture technology for the application in an IGCC. As a first critical step, the suitability of a K2CO3 promoted hydrotalcite-based CO2 sorbent is demonstrated by means of adsorption and regeneration experiments in the presence of 2000 ppm H2S. In multiple cycle experiments at 400 °C and 5 bar, the sorbent displays reversible co-adsorption of CO2 and H2S. The CO2 sorption capacity is not significantly affected compared to sulphur-free conditions. A mechanistic model assuming two different sites for H2S interaction explains qualitatively the interactions of CO2 and H2S with the sorbent. On the type A sites, CO2 and H2S display competitive sorption where CO2 is favoured. The type B sites only allow H2S uptake and may involve the formation of metal sulphides. This material behaviour means that the sour-SEWGS process likely eliminates CO2 and H2S simultaneously from the syngas and that an almost CO2 and H2S-free H2 stream and a CO2 + H2S stream can be produced. 相似文献
15.
Two sets of experiments on typical Class G well cement were carried out in the laboratory to understand better the potential processes involved in well leakage in the presence of CO2. In the first set, good-quality cement samples of permeability in the order of 0.1 μD (10?19 m2) were subjected to 90 days of flow through with CO2-saturated brine at conditions of pressure, temperature and water salinity characteristic of a typical geological sequestration zone. Cement permeability dropped rapidly at the beginning of the experiment and remained almost constant thereafter, most likely mainly as a result of CO2 exsolution from the saturated brine due to the pressure drop along the flow path which led to multi-phase flow, relative-permeability effects and the observed reduction in permeability. These processes are identical to those which would occur in the field as well if the cement sheath in the wellbore annulus is of good quality. The second set of experiments, carried out also at in situ conditions and using ethane rather than CO2 to eliminate any possible geochemical effects, assessed the effect of annular spaces between wellbore casing and cement, and of radial cracks in cement on the effective permeability of the casing-cement assemblage. The results show that, if both the cement and the bond are of good quality, the effective permeability of the assemblage is extremely low (in the order of 1 nD, or 10?21 m2). The presence of an annular gap and/or cracks in the order of 0.01–0.3 mm in aperture leads to a significant increase in effective permeability, which reaches values in the range of 0.1–1 mD (10?15 m2). The results of both sets of experiments suggest that good cement and good bonding with casing and the surrounding rock will likely constitute a good and reliable barrier to the upward flow of CO2 and/or CO2-saturated brine. The presence of mechanical defects such as gaps in bonding between the casing or the formation, or cracks in the cement annulus itself, leads to flow paths with significant effective permeability. This indicates that the external and internal interfaces of cements in wells would most probably constitute the main flow pathways for fluids leakage in wellbores, including both gaseous/supercritical phase CO2 and CO2-saturated brine. 相似文献
16.
Anna Korre Ji Quan Shi Claire Imrie Carlos Grattoni Sevket Durucan 《International Journal of Greenhouse Gas Control》2007,1(4):492-501
Laboratory studies and a number of field pilots have demonstrated that CO2 injection into coal seams has the potential to enhance coalbed methane (CBM) recovery with the added advantage that most of the injected CO2 can be stored permanently in coal. The concept of storing CO2 in geologic formations as a safe and effective greenhouse gas mitigation option requires public and regulatory acceptance. In this context it is important to develop a good understanding of the reservoir performance, uncertainties and the risks that are associated with geological storage. The paper presented refers to the sources of uncertainty involved in CO2 storage performance assessment in coalbed methane reservoirs and demonstrates their significance using extensive digital well log data representing the Manville coals in Alberta, Canada. The spatial variability of the reservoir properties was captured through geostatistical analysis, and sequential Gaussian simulations of these provided multiple realisations for the reservoir simulator inputs. A number of CO2 injection scenarios with variable matrix swelling coefficients were evaluated using a 2D reservoir model and spatially distributed realisations of total net thickness and permeability. 相似文献
17.
《International Journal of Greenhouse Gas Control》2007,1(2):223-235
Carbon dioxide contents of coals in the Sydney Basin vary both aerially and stratigraphically. In places, the coal seam gas is almost pure CO2 that was introduced from deep magmatic sources via faults and replaced pre-existing CH4. In some respects this process is analogous to sequestration of anthropogenic CO2. Laboratory studies indicate that CO2:CH4 storage capacity ratios for Sydney Basin coals are up to ∼2 and gas diffusivity is greater for CO2 by a factor of up to 1.5.Present-day distribution of CO2 in the coals is controlled by geological structure, depth and a combination of hydrostatic and capillary pressures. Under present-day P–T conditions, most of the CO2 occurs in solution at depths greater than about 650 m; at shallower depths, larger volumes of CO2 occur in gaseous form and as adsorbed molecules in the coal due to rapidly decreasing CO2 solubility. The CO2 has apparently migrated up to structural highs and is concentrated in anticlines and in up-dip sections of monoclines and sealing faults. CO2 sequestered in coal measure sequences similar to those of the Sydney Basin may behave in a similar way and, in the long term, equilibrate according to the prevailing P–T conditions.In situ CO2 contents of Sydney Basin coals range up to 20 m3/t. Comparisons of adsorption isotherm data measured on ground coal particles with in situ gas contents of Sydney Basin coals indicate that the volumes of CO2 stored do not exceed ∼60% of the total CO2 storage capacity. Therefore, the maximum CO2 saturation that may be achieved during sequestration in analogous coals is likely to be considerably lower than the theoretical values indicated by adsorption isotherms. 相似文献
18.
The oxyfuel process is one of the most promising options to capture CO2 from coal fired power plants. The combustion takes place in an atmosphere of almost pure oxygen, delivered from an air separation unit (ASU), and recirculated flue gas. This provides a flue gas containing 80–90 vol% CO2 on a dry basis. Impurities are caused by the purity of the oxygen from the ASU, the combustion process and air ingress. Via liquefaction a CO2 stream with purity in the range from 85 to 99.5 vol% can be separated and stored geologically. Impurities like O2, NOX, SOX, and CO may negatively influence the transport infrastructure or the geological storage site by causing geochemical reactions. Therefore the maximum acceptable concentrations of the impurities in the separated CO2 stream must be defined regarding the requirements from transportation and storage. The main objective of the research project COORAL therefore is to define the required CO2 purity for capture and storage. 相似文献
19.
《International Journal of Green Energy》2013,10(1):89-99
Abstract As one of the natural working fluids for the refrigeration system, CO2 has been attracting increasing attention over the last ten years. But CO2 has to work at the supercritical region for the so-called “condensation” process regarding the conventional refrigerants and evaporate at the two-phase region, and therefore results in larger throttling loss for the practical refrigeration application. Consequently, new technologies must be developed to improve the performance efficiency of the CO2 transcritical cycle, and make it to be equal or closer to that of the refrigeration system with the conventional refrigerants. In this study, an expander is employed in the CO2 transcritical cycle to replace the throttling valve, and as a result the throttling loss can be decreased significantly. The paper presents the development of a rolling piston expander and the activity items in the expander design, including the seal technology, the contact friction control, the suction design, etc. The performance experiments for the expander are conducted in the present testing system for the CO2 transcritical cycle. The results show that the recovery power of the expander is related to the revolution speed of the expander. The efficiency of the expander prototype is observed to be about 32%. 相似文献
20.
Paul M. Mathias Satish Reddy John P. O’Connell 《International Journal of Greenhouse Gas Control》2010,4(2):174-179
There is strong world-wide interest in developing new and improved processes for post-combustion capture of CO2, often using chemical absorption. Developers of new processes make positive claims for their proposals in terms of low energy consumption, but these are usually difficult to validate. This paper demonstrates that rigorous application of thermodynamic analysis and process simulation provides a powerful way to quantitatively estimate the energy requirements of CO2-capture processes by applying the methodology to the analysis and evaluation of the chilled-ammonia process. 相似文献