中国二氧化碳地质储存潜力评价与示范工程

2010—2012年,中国地质调查局水文地质环境地质调查中心承担完成的“全国二氧化碳地质储存潜力评价与示范工程计划项目”,全面建立了我国二氧化碳地质储存潜力与适宜性评价指标体系与评价技术方法,评价了主要沉积盆地的二氧化碳地质储存潜力与适宜性,完成了全国1∶500万评价图系和主要盆地评价图集编制,圈定出一批二氧化碳地质储存目标靶区;构建了深部咸水层二氧化碳地质储存工程选址、场地勘查与评价技术方法;与神华集团合作,在内蒙古鄂尔多斯市伊金霍洛旗成功实施了我国首个深部咸水层二氧化碳地质储存示范工程,基本形成了我国二氧化碳地质储存基本理论和技术方法体系。     

规模化深部咸水含水层CO2地质储存选址方法研究

本文依据中国沉积盆地CO2地质储存潜力评价结果,认为深部咸水含水层是实现规模化CO2地质储存的主体,进而对适宜CO2地质储存的深部咸水含水层属性进行了界定。提出了深部咸水含水层CO2地质储存选址原则,合理划分了选址工作阶段。建立了选址技术指标、安全性评价指标、经济适宜性和地面地质-社会环境选址指标4个指标层,60余个指标的选址指标体系,提出了基于层次分析(AHP)的多因子排序选址评价方法。本文的研究成果对中国深部咸水含水层CO2地质储存场地选址具有一定的指导意义。     

全国二氧化碳地质储存适宜性评价编图技术方法研究

将全国CO2地质储存潜力与适宜性评价工作划分为5个阶段,依次为区域级预测潜力(E级)评价、盆地级推定潜力(D级)评价、目标区级控制潜力(C级)评价、场地级基础储存量(B级)评价和灌注级工程储存量(A级)评价阶段.第一阶段编制的成果图件主要为全国1∶500万CO2地质储存成果图系;第二、三阶段主要编制沉积盆地CO2地质储存成果图集;第四、五阶段主要编制CO2地质储存示范工程成果图册.提出中国CO2地质储存潜力与适宜性评价和编图是一项有步骤、分阶段逐步完成的工程,评价及编图方法有待通过潜力与适宜性评价和编图的实践不断完善.     

四川盆地理论CO_2地质利用与封存潜力评估

结合CO_2地质利用与封存技术机理,在国际权威潜力评估公式的基础上,系统地提出了适合中国地质背景的次盆地尺度CO_2封存潜力评估方法及关键参数取值。同时,以四川盆地为例,依次开展了枯竭油田地质封存与CO_2强化石油开采、枯竭气田与CO_2强化采气、不可采煤层地质封存与CO_2驱替煤层气,以及咸水层地质封存技术的CO_2地质封存潜力。结果表明,四川盆地利用深部咸水层与枯竭天然气田CO_2地质封存潜力最大,期望值分别达154.20×10~8t和53.73×10~8t。其中,枯竭天然气田因成藏条件好、勘探程度高、基础建设完善,为四川盆地及其周边利用枯竭气田CO_2地质封存技术实现低碳减排提供了早期示范机会。CO_2地质利用与封存潜力评估方法,对进一步开展全国次盆地尺度理论封存潜力评估与工程规划具有重要意义。     

Effects of in-situ conditions on relative permeability characteristics of CO2-brine systems

Carbon dioxide capture and geological storage (CCGS) is an emerging technology that is increasingly being considered for reducing greenhouse gas emissions to the atmosphere. Deep saline aquifers provide a very large capacity for CO₂ storage and, unlike hydrocarbon reservoirs and coal beds, are immediately accessible and are found in all sedimentary basins. Proper understanding of the displacement character of CO₂-brine systems at in-situ conditions is essential in ascertaining CO₂ injectivity, migration and trapping in the pore space as a residual gas or supercritical fluid, and in assessing the suitability and safety of prospective CO₂ storage sites. Because of lack of published data, the authors conducted a program of measuring the relative permeability and other displacement characteristics of CO₂-brine systems for sandstone, carbonate and shale formations in central Alberta in western Canada. The tested formations are representative of the in-situ characteristics of deep saline aquifers in compacted on-shore North American sedimentary basins. The results show that the capillary pressure, interfacial tension, relative permeability and other displacements characteristics of CO₂-brine systems depend on the in-situ conditions of pressure, temperature and water salinity, and on the pore size distribution of the sedimentary rock. This paper presents a synthesis and interpretation of the results.     

Review: The potential impact of underground geological storage of carbon dioxide in deep saline aquifers on shallow groundwater resources

Underground geological storage of CO₂ in deep saline aquifers is considered for reducing greenhouse gases emissions into the atmosphere. However, some issues were raised with regard to the potential hazards to shallow groundwater resources from CO₂ leakage, brine displacement and pressure build-up. An overview is provided of the current scientific knowledge pertaining to the potential impact on shallow groundwater resources of geological storage of CO₂ in deep saline aquifers, identifying knowledge gaps for which original research opportunities are proposed. Two main impacts are defined and discussed therein: the near-field impact due to the upward vertical migration of free-phase CO₂ to surficial aquifers, and the far-field impact caused by large-scale displacement of formation waters by the injected CO₂. For the near-field, it is found that numerical studies predict possible mobilization of trace elements but concentrations are rarely above the maximum limit for potable water. For the far-field, numerical studies predict only minor impacts except for some specific geological conditions such as high caprock permeability. Despite important knowledge gaps, the possible environmental impacts of geological storage of CO₂ in deep saline aquifers on shallow groundwater resources appears to be low, but much more work is required to evaluate site specific impacts.     

神华碳封存示范项目中CO2注入分布模拟

CO2咸水层封存被广泛认为是一种具有大规模温室气体减排潜力的地学前缘技术。选取中国第一个全流程CCS项目为研究背景,结合工程实际情况,选取鄂尔多斯盆地为具体研究对象,提取相关参数,建立相应的地质模型,通过数值模拟研究咸水层多层统注时CO2在咸水中的主要封存机制、CO2在地层中的运移分布特征及其与注入能力的关系,并观测由于CO2注入引起的地层压力、CO2摩尔分数、酸碱度等的变化情况,为方案的进一步优化奠定基础。研究表明,CO2注入咸水层后,大部分进入储层上部,且注入能力越大时,注入的层位越多,注入量越大;CO2在咸水层中的存在形式有自由态、束缚态和溶解态。所有探索性研究的目的是给示范性项目的未来提供一个良好的基础优化方案。     

典型电厂海洋CO2地质储存场地选址适宜性评估

我国华东和东部沿海地区分布有大量的火电、水泥和炼油等CO₂排放源,但由于距离陆域大中型沉积盆地较远,限制了规模化的深部咸水层CO₂地质储存工程选址。本文以华能玉环电厂为实例,开展了东海陆架盆地瓯江凹陷场地选址适宜性评估。通过瓯江凹陷CO₂地质储存地质条件分析,初步圈定出了发育有利储盖层的目标靶区,并依次开展了地质安全性和经济适宜性分析。利用碳封存领导人论坛潜力评估公式,计算了目标靶区推荐储层的单位面积储存潜力;并在构建综合储集条件、地质安全性条件和经济适宜性条件的指标体系基础上,开展了GIS多源信息叠加评估,在丽水西次凹内筛选出两处较好的场地。研究对开展该区海域CO₂地质储存选址具有一定的探索意义。     

咸水层CO2地质封存地下利用空间评估方法研究

咸水层CO₂地质封存技术是我国实现碳中和目标的重要支撑技术,也是一项深部地下空间开发利用技术。咸水层CO₂地质封存工程利用的深部地下空间,需要在确定CO₂羽流、扰动边界和经济因素“三级边界”的基础上进行综合评估。以我国唯一的深部咸水层CO₂地质封存项目——国家能源集团鄂尔多斯碳捕集与封存(Carbon Capture and Storage, CCS)示范工程为实例,基于封存场地储层CO₂羽流监测以及扰动边界的推断预测结果综合评估,认为示范工程平面上4个1'×1'经纬度范围可作为地下利用空间平面边界,垂向上以纸坊组顶界(深度约958 m)为地下封存体顶部边界,以深度2 800 m为底板封隔层底界。提出的咸水层CO₂地质封存地下利用空间评估方法,能够为未来封存工程地下利用空间审批与监管提供一定参考,但也需要进一步结合已有法律法规及规模化封存工程实践完善提升。     

Simulation of CO2 plume movement in multilayered saline formations through multilayer injection technology in the Ordos Basin,China

Deep saline aquifers still remain a significant option for the disposal of large amounts of CO₂ from the atmosphere as a means of mitigating global climate change. The small scale Carbon Capture and Sequestration demonstration project in Ordos Basin, China, operated by the Shenhua Group, is the only one of its kind in Asia, to put the multilayer injection technology into practice. This paper aims at studying the influence of temperature, injection rate and horizontal boundary effects on CO₂ plume transport in saline formation layers at different depths and thicknesses, focusing on the variations in CO₂ gas saturation and mass fraction of dissolved CO₂ in the formation of brine in the plume’s radial three-dimensional field around the injection point, and interlayer communication between the aquifer and its confining beds of relatively lower permeability. The study uses the ECO2N module of TOUGH2 to simulate flow and pressure configurations in response to small-scale CO₂ injection into multilayer saline aquifers. The modelling domain involves a complex multilayer reservoir–caprock system, comprising of a sequence of sandstone aquifers and sealing units of mudstone and siltstone layers extending from the Permian Shanxi to the Upper Triassic Liujiagou formation systems in the Ordos Basin. Simulation results indicate that CO₂ injected for storage into deep saline aquifers cause a significant pressure perturbation in the geological system that may require a long duration in the post-injection period to establish new pressure equilibrium. The multilayer simultaneous injection scheme exhibits mutual interference with the intervening sealing layers, especially when the injection layers are very close to each other and the corresponding sealing layers are thin. The study further reveals that injection rate and temperature are the most significant factors for determining the lateral and vertical extent that the CO₂ plume reaches and which phase and amount will exist at a particular time during and after the injection. In general, a large number of factors may influence the CO₂–water fluid flow system considering the complexity in the real geologic sequence and structural configurations. Therefore, optimization of a CO₂ injection scheme still requires pursuance of further studies.     

Feasibility study of CO2 geological storage in China

It has been proved to be one effective means to reduce emissions of CO2 to mitigate the worsening global climate change through lots of projects and tests about CO2 geological storage. The sites that are suitable for CO2 geological storage include coal seams that can not be mined, deep saline aquifers, oil fields, and depleted gas fields. The emission of CO2 from fuel combustion is about 3.54 Gt in China in 2003, which is the second biggest in the world. Because the energy consumption in China mainly depends on fossil fuels for a long time in the future, China will become a country with the biggest emission of CO2 in the world, which will make China have to reduce the emissions of CO2 by some methods including geological storage. Based on lots of information about the reserves of coal seam methane and the rank of coal in the 68 coal basins in China, the total CO2 storage capacity in these coal basins was estimated according to the recovery coefficient and exchange ratio of CO2 to CHa.The total storage capacity in deep saline aquifers can be regarded as the total quantity of CO2 that can be dissolved in the saline aquifers at the depth from 1000m to 3000m under ground. The quantity can be estimated by multiplying the solubility of CO2 in the saline water and the volume of the appropriate aquifers. According to the reserve and quality of crude oil in 46 main oil basins in China, the CO2 storage capacity and the quantity of enhanced oil were calculated. The storage capacity of depleted gas fields can be derived from the reserve and depth of the gas fields. The total CO2 geological storage capacity is about 196.2 Gt CO2 that is as against 55.4 times the CO2 emission from fuel combustion in China in 2003. According to the results of the finished projects and tests about CO2-EOR and CO2-ECBM, the CO2 geological storage capacities in coal seams, deep saline aquifers, oil fields and depleted gas fields will be estimated.     

二氧化碳地质封存中的储存容量评估：问题和研究进展

二氧化碳地质封存被认为是一项非常有潜力的CO₂减排技术。其中对CO₂地质储存能力的评估可作为某一国家、某一区域或某一具体储层是否适合CO₂地质封存开展的判断依据之一。但目前的研究结果表明,对CO₂地质储存容量的评估并不是一个简单而直接的过程。介绍了由碳封存领导人论坛（CSFL）提出的用于不可采煤层、油气储层和深部咸水含水层中CO₂储存容量评估的方法。总结了影响CO₂地质储存容量评估的主要因素,为我国在CO₂地质封存领域研究的广泛合作提出了建议,有助于推动该技术在中国的深入开展。     

南海西部盐水层CO2埋存潜力评估

南海西部东方1-1、崖城13-1和乐东等气田具有CO2含量高的特点,每年从生产出的天然气中分离出大量的CO2。为了减少CO2在大气中的排放,考虑在莺歌海地区选择合适的盐水层埋存体,拟进行CO2地质埋存示范工程。根据CO2在盐水层中的各种埋存机理,并考虑盐水层构造特征对CO2运移分布的影响,提出了一种较为准确的CO2埋存潜力评估方法,并利用此方法对筛选出的5个备选盐水层进行了评估。评估结果表明,各盐水层埋存潜力巨大,都远远大于示范工程期限内预计的CO2埋存总量,并可将这些盐水层作为将来海南省及临近广东省人为CO2的埋存场所。南海西部东方1-1、崖城13-1和乐东等气田具有CO2含量高的特点,每年从生产出的天然气中分离出大量的CO2。为了减少CO2在大气中的排放,考虑在莺歌海地区选择合适的盐水层埋存体,拟进行CO2地质埋存示范工程。根据CO2在盐水层中的各种埋存机理,并考虑盐水层构造特征对CO2运移分布的影响,提出了一种较为准确的CO2埋存潜力评估方法,并利用此方法对筛选出的5个备选盐水层进行了评估。评估结果表明,各盐水层埋存潜力巨大,都远远大于示范工程期限内预计的CO2埋存总量,并可将这些盐水层作为将来海南省及临近广东省人为CO2的埋存场所。     

Europe’s longest-operating on-shore CO2 storage site at Ketzin, Germany: a progress report after three years of injection

The Ketzin pilot site, led by the GFZ German Research Centre for Geosciences, is Europe??s longest-operating on-shore CO₂ storage site with the aim of increasing the understanding of geological storage of CO₂ in saline aquifers. Located near Berlin, the Ketzin pilot site is an in situ laboratory for CO₂ storage in an anticlinal structure in the Northeast German Basin. Starting research within the framework of the EU project CO₂SINK in 2004, Ketzin is Germany??s first CO₂ storage site and fully in use since the injection began in June 2008. After 39?months of operation, about 53,000 tonnes of CO₂ have been stored in 630?C650?m deep sandstone units of the Upper Triassic Stuttgart Formation. An extensive monitoring program integrates geological, geophysical and geochemical investigations at Ketzin for a comprehensive characterization of the reservoir and the CO₂ migration at various scales. Integrating a unique field and laboratory data set, both static geological modeling and dynamic simulations are regularly updated. The Ketzin project successfully demonstrates CO₂ storage in a saline aquifer on a research scale. The results of monitoring and modeling can be summarized as follows: (1) Since the start of the CO₂ injection in June 2008, the operation has been running reliably and safely. (2) Downhole pressure data prove correlation between the injection rate and the reservoir pressure and indicates the presence of an overall dynamic equilibrium within the reservoir. (3) The extensive geochemical and geophysical monitoring program is capable of detecting CO₂ on different scales and gives no indication for any leakage. (4) Numerical simulations (history matching) are in good agreement with the monitoring results.     

Impacts of mineralogical compositions on different trapping mechanisms during long-term CO<Subscript>2</Subscript> storage in deep saline aquifers

Deep saline aquifers in sedimentary basins are considered to have the greatest potential for CO₂ geological storage in order to reduce carbon emissions. CO₂ injected into a saline sandstone aquifer tends to migrate upwards toward the caprock because the density of the supercritical CO₂ phase is lower than that of formation water. The accumulated CO₂ in the upper portions of the reservoir gradually dissolves into brine, lowers pH and changes the aqueous complexation, whereby induces mineral alteration. In turn, the mineralogical composition could impose significant effects on the evolution of solution, further on the mineralized CO₂. The high density of aqueous phase will then move downward due to gravity, give rise to “convective mixing,” which facilitate the transformation of CO₂ from the supercritical phase to the aqueous phase and then to the solid phase. In order to determine the impacts of mineralogical compositions on trapping amounts in different mechanisms for CO₂ geological storage, a 2D radial model was developed. The mineralogical composition for the base case was taken from a deep saline formation of the Ordos Basin, China. Three additional models with varying mineralogical compositions were carried out. Results indicate that the mineralogical composition had very obvious effects on different CO₂ trapping mechanisms. Specific to our cases, the dissolution of chlorite provided Mg²⁺ and Fe²⁺ for the formation of secondary carbonate minerals (ankerite, siderite and magnesite). When chlorite was absent in the saline aquifer, the dominant secondary carbon sequestration mineral was dawsonite, and the amount of CO₂ mineral trapping increased with an increase in the concentration of chlorite. After 3000 years, 69.08, 76.93, 83.52 and 87.24 % of the injected CO₂ can be trapped in the solid (mineral) phase, 16.05, 11.86, 8.82 and 6.99 % in the aqueous phase, and 14.87, 11.21, 7.66 and 5.77 % in the gas phase for Case 1 through 4, respectively.     

Establishment of an assessment method for site-scale suitability of CO2 geological storage

Geological storage of CO2 (known as geological sequestration) is increasingly seen as a viable strategy to reduce the release of greenhouse gases into the atmosphere. China has become one of the largest emitters of CO2 in the world. Therefore, alongside other emissions reductions measures, the deployment of geological storage projects to capture CO2 in China is essential. This paper focuses on the establishment of qualitative and quantitative assessment methods for site-scale suitability of CO2 geological storage in deep saline formation systems. This is based on numerical modelling prior to the development a specific geological storage project, providing a more accurate selection of preferential sites from a list of potential storage locations. However, the detailed design of specific geological storage projects was not con?sidered.     

Potential for deep geological sequestration of CO2 in Switzerland: a first appraisal

Possibilities to sequester anthropogenic CO₂ in deep geological formations are being investigated worldwide, but the potential within Switzerland has not yet been evaluated. This study presents a first-order appraisal based solely on geological criteria collated from the literature. The Swiss Molasse Basin (SMB) and the adjacent Folded Jura are the only realms of the country where CO₂ could conceivably be stored in saline aquifers. Evaluation of geological criteria at the basin-wide scale shows that the SMB–Jura has moderate potential (score of 0.6 on a scale from 0 to 1) when compared to basins elsewhere. At the intrabasinal scale, inspection of the stratigraphy reveals four regional candidate aquifers that are sealed by suitable caprocks: top Basement plus basal Mesozoic sandstones, all sealed by the Anhydrite Group; Upper Muschelkalk sealed by the Gipskeuper; Hauptrogenstein sealed by the Effinger Member, and Upper Malm plus Lower Cretaceous sealed by the Lower Freshwater Molasse. Nine geological criteria are defined to evaluate the storage potential of these and other smaller scale candidates. A numerical scoring and weighting scheme allows the criteria to be assessed simultaneously, permitting the storage potential to be depicted using the 0–1 scale in contoured maps. Approximately 5,000 km² of the central SMB exhibits potentials between 0.6 and 0.96. The Fribourg–Olten–Luzern area is the most favoured owing to the presence of several sealed aquifers within the preferred 800–2,500 m depth interval, and to its low seismicity, low geothermal gradient, low fault density, and long groundwater residence times. Smaller areas with good potential lie between Zürich and St. Gallen. In contrast, western Switzerland, the Jura and the southern SMB have markedly poorer potential. Considering only the portions of the aquifers with potential above 0.6, the theoretical, effective storage capacity of the basin is estimated to be 2,680 million tonnes of CO₂.     

Optimal selection of different CCS technologies under CO2 reduction targets

In China, carbon capture and storage (CCS) is recognized as one of the most promising technologies through which to achieve a large reduction in CO₂ emissions in future. The choice among different CCS technologies is critical for large-scale applications. With the aim of developing instructive policy suggestions for CCS development, this study proposed an interval programming model to select the optimal CCS technology among the different CCS technologies available in China. The analysis results indicate that the selection of CO₂ capture technologies should be based on the actual situation of the project and industry being targeted. If the government implements mandatory CO₂ emission reductions, storage in deep saline aquifers is the optimal choice for CO₂ sequestration when oil prices are low and the number of available CO₂ emission permits is large. In contrast, enhanced oil recovery is the optimal choice when oil prices increase and the availability of CO₂ emission permits decreases. It is critical that the government reduce the operating cost and the cost of CO₂ capture in particular.

     

Regional search, selection and geological characterization of a large anticlinal structure, as a candidate site for CO2-storage in northern Germany

This paper reports on the regional screening, selection and geological characterisation of a potential on-shore CO₂ storage site (saline aquifer) in north-eastern Germany. The main objective of this study was to identify and investigate a candidate storage site, capable to accommodate the total amount of approximately 400 million tons of CO₂. Such a volume is produced by a modern, lignite-fired power plant within its operation lifetime of approximately 40 years. Within north-eastern Germany, several saline aquifers of Triassic, Jurassic and Cretaceous age have been evaluated with respect to their regional occurrence, storage potential and basic reservoir properties. Subsequent to a ranking, considering different criteria, the anticlinal structure Schweinrich holding suitable saline aquifers of the uppermost Triassic and lowest Jurassic has been selected from a number of identified candidate sites. According to results of the geological site characterisation, including structural geological investigations and 3D reservoir modelling, the structure Schweinrich seems to be a suitable site for industrial large scale CO₂ storage. Further data acquisition (new wells and 3D seismics) and research (more detailed and comprehensive modelling) is needed in order to prove the structural integrity of the storage site and assure long-term safety.     

Feasibility of geoelectrical monitoring and multiphase modeling for process understanding of gaseous CO2 injection into a shallow aquifer

Potential pathways in the subsurface may allow upwardly migrating gaseous CO₂ from deep geological storage formations to be released into near surface aquifers. Consequently, the availability of adequate methods for monitoring potential CO₂ releases in both deep geological formations and the shallow subsurface is a prerequisite for the deployment of Carbon Capture and Storage technology. Geoelectrical surveys are carried out for monitoring a small-scale and temporally limited CO₂ injection experiment in a pristine shallow aquifer system. Additionally, the feasibility of multiphase modeling was tested in order to describe both complex non-linear multiphase flow processes and the electrical behavior of partially saturated heterogeneous porous media. The suitability of geoelectrical methods for monitoring injected CO₂ and geochemically altered groundwater was proven. At the test site, geoelectrical measurements reveal significant variations in electrical conductivity in the order of 15?C30?%. However, site-specific conditions (e.g., geological settings, groundwater composition) significantly influence variations in subsurface electrical conductivity and consequently, the feasibility of geoelectrical monitoring. The monitoring results provided initial information concerning gaseous CO₂ migration and accumulation processes. Geoelectrical monitoring, in combination with multiphase modeling, was identified as a useful tool for understanding gas phase migration and mass transfer processes that occur due to CO₂ intrusions in shallow aquifer systems.