世界地质储层二氧化碳理论埋存量评价技术研究

埋存CO2是避免气候变化的有效途径之一,地下埋存可供选择的主要方式包括枯竭油气藏埋存、深部盐水储层埋存、不能开采的煤层埋存以及深海埋存等。介绍了各种CO2埋存方式的埋存机理,分析了不同方式下CO2埋存量的各种计算方法。同时给出了IEA和IPCC评估的世界储层CO2埋存量,评估结果表明,深部盐水层可提供巨大的埋存潜力,在400～10000Gt之间;枯竭油气藏也具有很大的埋存潜力,可以埋存全部需埋存C02的40％。CO2地质储层埋存将对全球CO2减排起到举足轻重的作用。     

中国二氧化碳捕捉与封存(CCS)技术早期实施方案构建研究

一个完整的二氧化碳捕捉与封存(CCS)系统包含了捕捉、运输和封存三个环节,且每个环节又有多种技术选择,在CCS大规模推广的初期,如何根据本国国情,选择最合适的备选技术进行组合,构建最佳的实施方案,已成为CCS研究中一个亟待解决的问题.为此引入CCS链的概念,从排放源、捕捉技术、运输技术和封存技术4个方面分析比较CCS各备选技术的优势和不足.对于老电厂的CCS改造,超临界是最佳的实施对象;而对于新建电厂,IGCC是最佳的实施对象.燃烧后捕捉将是匹配煤粉(PC)电厂的捕捉技术,而燃烧前捕捉则应匹配新建IGCC电厂.管道运输将是我国早期实施CCS的运输方式.注二氧化碳驱油提高采收率(CO2-EOR)和深部盐水层封存将是我国早期实施CCS的首选封存技术.最终构建了4条CCS链作为我国早期的CCS实施方案,即超临界PC电厂+燃烧后捕捉+管道运输+EOR封存;超临界PC电厂+燃烧后捕捉+管道运输+深部盐水层封存;IGCC电厂+燃烧前捕捉+管道运输+EOR封存;IGCC电厂+燃烧前捕捉+管道运输+深部盐水层封存.     

德国政府通过二氧化碳捕集与封存法律草案

德国政府于2012年4月13日通过了二氧化碳捕集、运输与永久封存技术示范与应用法律草案。这为德国得到欧盟支持,开展二氧化碳捕集与封存(CCS)测试项目提供了先决条件。这份法律草案的主要内容包括:①将封存限制在示范用途:只有当封存设施在2016年底前提交申请,才能够得到许可,而且每个设备的年度封存量不能超过300×104t,每年全国的二氧化碳封存总量不能超过800×104t。②示范封存设施许     

世界二氧化碳减排政策与储层地质埋存展望

阐述了因温室气体排放所引起的全球气候变暖和环境问题,介绍了国际社会的各种二氧化碳减排政策,提出了利用二氧化碳埋存提高石油采收率的技术,分析了二氧化碳埋存方式及世界二氧化碳埋存量的评估值。     

二氧化碳汽车空调压缩机的热力性能模拟

二氧化碳汽车空调系统中压缩机是主要的耗能部件,对压缩机热力参数准确计算有利于其优化改进,通过建立二氧化碳汽车空调制冷压缩机稳态模型,对二氧化碳质量流量、压缩机输入功率和压缩机排气温度进行了仿真计算,在美国汽车空调协会制定的3个标准工况下,采用意大利Dorin生产的CD180H型单极定频活塞式二氧化碳压缩机进行实验研究,稳态模型对压缩机的性能预测和压缩机实验情况下对比分析表明:二氧化碳质量流量、压缩机输入功率和压缩机排气温度均随着压比增加而增加,二氧化碳流量和压缩机输入功率仿真值和实验值的绝对误差分别在7.3%和8.7%以内,排气温度仿真值和压缩机实验值的绝对误差在14.2%以内,模型预测值和实验值吻合较好,可以满足工程项目计算需要。     

低温地板辐射采暖埋管结构尺寸设计实验研究

建立低温地板辐射采暖的传热模型,通过实测及理论计算,得出各表面之间的对流及辐射换热量,通过对换热表面的合理简化,得出地板辐射采暖表面温度与埋管层厚度、埋管间距的关系,为地板辐射采暖设计时确定埋管结构尺寸提供依据。     

沸腾燃烧锅炉的埋管辐射换热及其试验

在沸腾燃烧锅炉内的埋管传热中,料层对埋管的辐射换热占有一定份额。目前在沸腾炉的埋管传热计算中,尚无合适的计算公式。在现有采用的热力计算方法中,只计算埋管的总放热系数,而无辐射放热系数的计算公式。本文通过对燃烧沸腾层的辐射热流测量,并通过理论分析,得到适合于燃用     

平原水库浸没地下水临界埋深分析

平原水库蓄水易产生水库浸没,危害周围农作物和建筑物,需确定平原水库地下水临界埋深。对于农作物,水库浸没导致农作物发生渍害和次生盐渍化,利用作物根系层厚度计算防止农作物发生渍害的临界埋深;引入矿化度级差计算防止土壤次生盐渍化的临界埋深,选取两者最大值作为农作物浸没临界埋深。对于建筑物,引入弹塑体结构计算模型,根据承载力与地基应力的关系计算承载力影响下的临界埋深,根据应力分层总和法确定受附加应力影响的临界埋深,最后利用层次分析法计算权重大小,综合考虑各因素确定建筑物浸没临界埋深。通过提出地下水临界埋深评价方法为减轻浸没危害、预测库区可能发生浸没的地区范围提供了依据。     

二氧化碳驱油技术

简单来说,二氧化碳驱油技术就是把二氧化碳注入油层中以提高采油率。国际能源机构评估认为,全世界适合二氧化碳驱油开发的资源约为3000×108～6000×108bbl。由于二氧化碳是一种在油和水中溶解度都很高的气体,当它大量溶解于原油中时,可使原油体积膨胀、黏度下降,还可降低油水间的界面张力。与其他驱油技术相比,二氧化碳驱油具有适用范围大、驱油成本低、采油率提高显著等优点。二氧化碳驱油技术是石油公司发展碳封存的重要技术路径,是实现二氧化碳资源利用和封存的最佳结合点之一。大     

富氧燃烧技术的研究进展与分析

分别介绍了富氧燃烧的原理、氧气的制取、对运行的影响和产物二氧化碳运输与封存等技术的基础上,进行了比较分析,提出了面对二氧化碳减排的严峻形势,在火力发电厂中应用富氧燃烧技术结合二氧化碳封存等技术是减少二氧化碳排放的一条行之有效的技术路径,具有较好的发展潜力.     

Sequestration of CO2 in geological media in response to climate change: capacity of deep saline aquifers to sequester CO2 in solution

Geological sequestration is a means of reducing anthropogenic atmospheric emissions of CO₂ that is immediately available and technologically feasible. Among various options, CO₂ can be sequestered in deep aquifers by dissolution in the formation water. The ultimate CO₂ sequestration capacity in solution (UCSCS) of an aquifer is the difference between the total capacity for CO₂ at saturation and the total inorganic carbon currently in solution in that aquifer, and depends on the pressure, temperature and salinity of the formation water. Assuming non-reactive aquifer conditions, the current carbon content is calculated using standard chemical analyses of the formation waters collected by the energy industry on the basis of the concentration of carbonate and bicarbonate ions. Formation water analyses performed at laboratory conditions are brought to in situ conditions using a geochemical speciation model to account for dissolved gasses that are lost from the water sample. To account for the decrease in CO₂ solubility with increasing water salinity, the maximum CO₂ content in formation water is calculated by applying an empirical correction to the CO₂ content at saturation in pure water. The UCSCS in an aquifer is calculated by considering the effect of dissolved CO₂ on the formation water density, the aquifer thickness and porosity to account for the volume of water in the aquifer pore space and for the mass of CO₂ dissolved in the water currently and at saturation. The methodology developed for estimating the ultimate CO₂ sequestration capacity in solution in aquifers has been applied to the Viking aquifer in the Alberta basin in western Canada. Considering only the region where the injected CO₂ would be a dense fluid, the capacity of the Viking aquifer to sequester CO₂ in solution in the formation water is calculated to be 100 Gt. Simple estimates then indicate that the capacity of the Alberta basin to sequester CO₂ dissolved in the formation waters at depths greater than 1000 m is on the order of 4000 Gt CO₂. The results also show that using geochemical models to bring the analyses of the formation waters to in situ conditions is not warranted when the current total inorganic carbon (TIC) in the aquifer water is very small by comparison with the CO₂ solubility at saturation. Furthermore, in such cases, the current TIC may even be neglected.     

CO2 sequestration in Ontario, Canada. Part II: cost estimation

As the Kyoto target set for Canada is to reduce GHG emission by 6% of the 1990 level by 2008–2012, several options are being considered to achieve this target. One of the possible options in Ontario is geological sequestration of captured CO₂ in saline aquifers, where CO₂ is expected to be stored for long geological periods, from 100 to several thousand years depending on the size, property and location of the reservoir. The preferred concept is to inject CO₂ into a porous and permeable reservoir covered with a cap rock located at least 800 m beneath the earth's surface where CO₂ can be stored under supercritical conditions. This paper evaluates the capital and operating cost for CO₂ sequestration in southwestern Ontario from a 500 MW coal fired power plant. The main focus is on the cost of sequestration (CO₂ transport and injection), and thus, the cost of capturing and pressurizing the CO₂ from the plant flue gas is not considered here.

A significant amount of capital investment is necessary to transfer CO₂ from a 500 MW fossil fuel power plant to the injection location and to store it underground. Major components of the cost include: cost of pipeline, cost of drilling injection wells and installing platforms, since the more plausible injection area is under Lake Erie. Many uncertainties are associated with cost estimation; several are identified and their impacts are considered in this paper. The estimated cost of sequestration of 14,000 ton/day of CO₂ at approximately 110 bar in southwestern Ontario is between 7.5 and 14 US$/ton of CO₂ stored.     

Thermo-economic analysis of a direct supercritical CO2 electric power generation system using geothermal heat

A comprehensive thermo-economic model combining a geothermal heat mining system and a direct supercritical CO₂ turbine expansion electric power generation system was proposed in this paper. Assisted by this integrated model, thermo-economic and optimization analyses for the key design parameters of the whole system including the geothermal well pattern and operational conditions were performed to obtain a minimal levelized cost of electricity (LCOE). Specifically, in geothermal heat extraction simulation, an integrated wellbore-reservoir system model (T2Well/ECO2N) was used to generate a database for creating a fast, predictive, and compatible geothermal heat mining model by employing a response surface methodology. A parametric study was conducted to demonstrate the impact of turbine discharge pressure, injection and production well distance, CO₂ injection flowrate, CO₂ injection temperature, and monitored production well bottom pressure on LCOE, system thermal efficiency, and capital cost. It was found that for a 100 MW_e power plant, a minimal LCOE of $0.177/kWh was achieved for a 20-year steady operation without considering CO₂ sequestration credit. In addition, when CO₂ sequestration credit is $1.00/t, an LCOE breakeven point compared to a conventional geothermal power plant is achieved and a breakpoint for generating electric power generation at no cost was achieved for a sequestration credit of $2.05/t.     

Spray characteristics and controlling mechanism of fuel containing CO2

This paper presents studies of spray characteristics and controlling mechanism of fuel containing CO₂. Using diesel fuel containing CO₂ gas, experiments were conducted on diesel hole-type nozzles and simple nozzles. The steady spray and transient spray characteristics were observed and measured by instantaneous shadowgraphy, high-speed photography, phase Doppler anemometry (PDA) and LDSA respectively. The effects of CO₂ concentration in the fuel, the injection pressure, the nozzle L/D ratio, surrounding gas pressure and temperature on the atomization behavior and spray pattern were evaluated. The results show that the injection of fuel containing CO₂ can greatly improve the atomization and produce a parabolic-shaped spray; and the CO₂ gas concentration, surrounding gas pressure, temperature and nozzle configuration have dominant influences on spray characteristics of the fuel containing CO₂. New insight into the controlling mechanism of atomization of the fuel containing CO₂ was provided.     

Expulsive force in the development of CO2 sequestration: application of SC-CO2 jet in oil and gas extraction

With the rapid development of global economy, an increasing amount of attention has been paid to the emission of greenhouse gases, especially CO₂. In recent years, dominated by the governments around the world, several significant projects of CO₂ sequestration have been conducted. However, due to the huge investment and poor economic effects, the sustainability of those projects is not satisfactory. Supercritical CO₂ (SC-CO₂) has prominent advantages in well drilling, fracturing, displacement, storage, plug and scale removal within tubing and casing, which could bring considerable economic benefits along with CO₂ sequestration. In this paper, based on physicochemical properties of SC-CO₂ fluid, a detailed analysis of technical advantages of SC-CO₂ applied in oil and gas development is illustrated. Furthermore, the implementation processes of SC-CO₂ are also proposed. For the first time, a recycling process is presented in which oil and gas are extracted and the CO₂ generated could be restored underground, thus an integrated technology system is formed. Considering the recent interests in the development of enhancing hydrocarbon recoveries and CO₂ sequestration, this approach provides a promising technique that can achieve these two goals simultaneously.     

Basic experimental results of liquid CO2 injection intothe deep ocean

CO₂ disposal in the deep ocean is expected to be an effective option for mitigating the increase in CO₂ on the earth. The authors have investigated the behaviour of liquid CO₂ using test facilities which can simulate the pressure and temperature of the deep ocean. Phase equilibrium data of the CO₂ -seawater system and the conditions of CO₂ clathrate formation were confirmed. In addition, the authors measured the pH value of seawater saturated with CO₂ at high pressure. The data presented in this paper are considered indispensable for evaluating the possibility of CO₂ disposal in the deep ocean     

CO2单井增强地热系统取热性能研究

为提高闭式单井系统取热性能,提出一种CO2单井增强地热系统（CO2-SEGS）。建立井筒流动换热和储层热-流-固耦合的数学模型,考虑CO2可压缩性以及井纵向压力传递特性,对比分析了水和CO2在SEGS中的取热性能,研究系统取热性能与封隔间距、井筒保温的关系。结果表明：（1）额定循环流量下,井口生产温度从134.09℃降低至116.06℃;CO2在采出过程中降压膨胀做功,产生明显的温降效应,中心管井口温度比底部低约57℃。（2）井筒不同位置处CO2的密度、热容差异很大,当循环流量小于50 kg/s时,依靠浮升力作用,SEGS可实现自主循环运行,无需额外泵功。（3）当水和CO2的流量分别为15 kg/s和40 kg/s时,两者年均取热速率近似相等,CO2的采出温度比水低约40℃,而压力损耗远小于水。（4）SEGS取热性能与封隔间距以及中心管保温性能呈正相关。研究结果可为SEGS系统的开发提供参考。     

A study of safe CO2 storage capacity in saline aquifers: a numerical study

An effective way of reducing greenhouse gas content in the atmosphere is carbon dioxide (CO₂) geo‐sequestration in saline aquifers. The main objective of this study is to develop a 3‐D numerical model to identify the optimum CO₂ storage capacity in saline aquifers by studying the factors affecting it and the possibility of the injected CO₂ back‐migrating into the atmosphere. A 1000m×1000m×184 m saline aquifer, lying 800 m below the ground surface, was therefore considered to develop a model using the COMET 3 reservoir simulator. The effects of injecting CO₂ properties (injection pressure) and the aquifer's properties (depth, temperatures and salinity) on the CO₂ storage capacity were examined first. According to the results of the model, CO₂ storage capacity increases with increasing injection pressure and salinity and decreasing depth and temperature, and 100% variations in injection pressure, depth, temperature and salinity levels cause the CO₂ storage capacity to be changed by 54%, 36%, 18% and 1.8%, respectively. The next stage of the study involved the determination of cap rock failure due to CO₂ injection pressure and the identification of the factors influencing it. A detailed parametric study was conducted, with changes to the depth, temperature and salinity with respect to injection pressure, to detect the effects of these factors on the optimum CO₂ injection pressure. According to the results, optimum CO₂ injection pressure clearly depends on the aquifer depth and the effects of salinity and temperature are negligible. An increment of 0.8 to 1.4 km in aquifer depth causes the optimum injection pressure to be increased from 19.55 to 42 MPa, which is about 10⁵ and 10⁷ higher than the effects of temperature (20 to 110 °C increment) and salinity level (100,000 to 160,000 ppm increment), respectively. The model can be used effectively in field studies to safely enhance CO₂ storage capacity in saline aquifers. Copyright © 2012 John Wiley & Sons, Ltd.     

水合物法分离CO2工艺研究进展

随着温室效应加剧,CO₂减排行动已迫在眉睫。水合物法分离CO₂工艺作为一种发展前景广阔的新型CO₂分离技术,为CO₂减排提供了一种解决思路。水合物法分离CO₂工艺相比于化学吸收、物理吸附、深冷分离和膜分离等技术具有分离效率高、过程简单无副产物、条件温和的优势,为减缓CO₂排放增加对环境造成的影响提供了一个中短期解决方案,以此为前提将允许人类继续使用化石燃料直至可再生能源技术广泛应用。本文综合分析了国内外的相关文献,介绍了水合物法分离CO₂工艺的基本原理,并比较了水合物法分离CO₂不同工艺的优劣之处,为进一步优化水合物法分离CO₂工艺提供指导。     

Why does CO2 hydrate disposed of in the ocean in the hydrate-formation region dissolve in seawater?

The fate of CO₂ hydrate disposed of in the ocean is analyzed based on thermodynamic theory. It is found that CO₂ hydrate and seawater form a stable system only when (a) the system pressure p and temperature T fall within the hydrate-formation region in the ocean (i.e. p > 4.5MPa and T < 283 K) and (b) seawater is saturated or supersaturated with respect to CO₂. At ocean depths below 440 m, the pressure and temperature required for system stability are satisfied. However, since seawater is highly unsaturated with respect to CO₂, the requirement for full thermodynamic stability cannot be met because the hydrate and seawater are not in chemical equilibrium and the chemical potential for CO₂ in the hydrate is larger than that in seawater. Therefore, the hydrate is unstable and dissolves in seawater. Thus, CO₂ hydrate disposed of in the ocean may not be a long-lived entity in the ocean as was predicted previously by many investigators. The results of our study have been confirmed by laboratory simulations.