CO2地质封存时移垂直地震监测技术

神华CO2捕获和封存（carbon capture and storage,CCS）示范项目是我国首个全流程煤基CO2捕获和在低孔低渗深部咸水层进行多层注入的CO2封存示范项目,意在通过时移垂直地震（VSP）监测CO2地质封存状况。介绍了CO2地质封存时移VSP技术和监测效果。通过注气前后3次VSP观测,得到了高品质时移VSP资料,研究了一致性处理技术、矢量波场分离和多波成像技术,获得了高分辨率的多波时移VSP剖面,通过深度域标定和多种属性解释对比,分析了注气前后VSP地震响应特征,预测了CO2地下运移范围,达到CCS项目预期监测目标。结果证明,时移VSP技术是监测CO2地质封存与运移的有效技术手段。     

Long‐Term Reaction Characteristics of CO2–Water–Rock Interaction: Insight into the Potential Groundwater Contamination Risk from Underground CO2 Storage

CO₂ sequestration into saline aquifers is considered to be one of the most promising options for reducing industrial CO₂ emissions to the atmosphere. However, there are still many uncertainties regarding the storage of CO₂ in the subsurface because of a lack of knowledge about CO₂–water–rock interaction within CO₂ reservoirs and the potential risk of CO₂ leakage. In this study, we construct a semi‐open type experimental system that can reproduce the interactions under conditions close to those of actual CO₂ reservoirs. Using the system, we conduct CO₂–water–rock interaction experiments for 8 months to monitor the long‐term reaction and the mobilization of harmful metal elements. Altered tuffaceous rock is used in the experiment because these tuffaceous rock formations (called “Green Tuff”) are a potential candidate for CO₂ storage in Japan. The results show that the major‐element water composition will converge to the point where host rock dissolution and secondary mineral precipitation are balanced; then, the interaction will proceed under a certain groundwater composition. In addition, we found that groundwater contamination by some metal elements (Ni, Ba, and Mn) may reach unsafe levels for drinking water as a result of CO₂‐water–rock interaction.     

Natural 222Rn as a tracer of mixing and volatilization in a shallow aquifer during a CO2 injection experiment

This study aims to evaluate the application of ²²²Rn in groundwater as a tracer for monitoring CO₂ plume migration in a shallow groundwater system, which is important to detect potential CO₂ leakage in the carbon capture and storage (CCS) project. For this research, an artificial CO₂-infused water injection experiment was performed in a shallow aquifer by monitoring hydrogeochemical parameters, including ²²²Rn. Radon in groundwater can be a useful tracer because of its sensitivity to sudden changes in subsurface environment. To monitor the CO₂ plume migration, the data were analysed based on (a) the influence of mixing processes on the distribution of ²²²Rn induced by the artificial injection experiment and (b) the influence of a carrier gas role by CO₂ on the variation of ²²²Rn. The spatio-temporal distributions of radon concentrations were successfully explained in association with horizontal and vertical mixing processes by the CO₂-infused water injection. Additionally, the mixing ratios of each monitoring well were calculated, quantitatively confirming the influence of these mixing processes on the distribution of radon concentrations. Moreover, one monitoring well showed a high positive relationship between ²²²Rn and Total dissolved inorganic carbon (TIC) by the carrier gas effect of CO₂ through volatilization from the CO₂ plume. It indicated the applicability of ²²²Rn as a sensitive tracer to directly monitor CO₂ leakage. When with a little effect of carrier gas, natural ²²²Rn in groundwater can be used to compute mixing ratio of CO₂-infused water indicative of CO₂ migration pathways. CO₂ carrier gas effect can possibly increase ²²²Rn concentration in groundwater and, if fully verified with more field tests, will pose a great potential to be used as a natural tracer for CO₂.     

The threat to climate change mitigation posed by the abundance of fossil fuels

This article analyses the trends in primary demand for fossil fuels and renewables, comparing regions with large and small domestic fossil fuel reserves. We focus on countries that hold 80% of global fossil fuel reserves and compare them with key countries that have meagre fossil fuel reserves. We show that those countries with large domestic fossil fuel reserves have experienced a large increase in primary energy demand from fossil fuels, but only a moderate or no increase in primary energy from renewables, and in particular from non-hydro renewable energy sources (NHRES), which are assumed to represent the cornerstone of the future transformation of the global energy system. This implies a tremendous threat to climate change mitigation, with only two principal mitigation options for fossil-fuel-rich economies if there is to be compliance with the temperature goals of the Paris Agreement: (1) leave the fossil fuels in the ground; and (2) apply carbon capture and storage (CCS) technologies. Combinations of these two options to exploit their respective possibilities synergistically will require strong initiatives and incentives to transform a certain amount of the domestic fossil fuel reserves (including the associated infrastructure) into stranded assets and to create an extensive CCS infrastructure. Our conclusion is that immediate and disruptive changes to the use of fossil fuels and investments in non-carbon-emitting technologies are required if global warming is to be limited to well below 2°C. Collective actions along value chains in business to divert from fossil fuels may be a feasible strategy.

Key policy insights

• The main obstacle to compliance with any reasonable warming target is the abundance of fossil fuels, which has maintained and increased momentum towards new fossil-fuelled processes.

• So far, there has been no increase in the share of NHRES in total global primary energy demand, with a clear decline in the NHRES share in India and China.

• There is an immediate need for the global community to develop fossil fuel strategies and policies.

• Policies must account for the global trade flow of products that typically occurs from the newly industrialized fossil fuel-rich countries to the developed countries.

     

Research Progress of 4D Multicomponent Seismic Monitoring Techniquein Carbon Capture and Storage

Carbon Capture and Storage (CCS) technology is currently recognized as the most effective way to mitigate greenhouse gas. CO₂ geological storage is the key technique in CCS, and monitoring the safety of CO₂ geological storage runs through the whole CCS project from CO₂ injection and after closure. 4D seismic monitoring technique is the most effective way to monitor the leakage of CO₂ and to confirm the safety of CO₂ sequestration. Traditional 4D seismic technology predicts saturation of CO₂ and pressure distribution in reservoir by comparing two vintages seismic amplitude and travel time from two or repeated 3D seismic data before and after CO₂ injection or between two different injection stages. 4D multicomponent seismic monitoring has a great potential to be explored. Because shear wave velocity is sensitive to pressure, we may discriminate pore pressure distribution by using 4D multicomponent seismic information. For anisotropy reservoir, we may confirm the change of reservoir fissures and fractures as well as reservoir and caprock stress status before and after CO₂ injection through comparing difference of travel time and amplitude of PS₁ and PS₂ wave in two vintages seismic acquisition. Furthermore, we will find out potential CO₂ leakage risk area more accurately and evaluate the safety of CO₂ sequestration more reliablely by combining rock physics experiment and dipole sonic log data with 4D multicomponent seismic monitoring.     

Carbon capture and storage in developing countries: A comparison of Brazil, South Africa and India

The ambition to introduce carbon capture and storage (CCS) technology in developing countries raises particular considerations and challenges, where, most fundamentally, pressing socio-economic needs imply that there are other political priorities than GHG mitigation. This suggests that the interest in, and viability of, large-scale deployment of CCS in developing countries has to be analyzed as a strategic issue in the overall context of national development. But what are then the strategic concerns that may influence developing countries’ decisions to pursue large-scale deployment of CCS technology? The present article takes a first step in answering this question by comparing CCS policies and ongoing activities in Brazil, India and South Africa.     

An International Relations perspective on the global politics of carbon dioxide capture and storage

With the publication of the IPCC Special Report on Carbon dioxide Capture and Storage (CCS), CCS has emerged as a focal issue in international climate diplomacy and energy collaboration. This paper has two goals. The first goal is to map CCS activities in and among various types of intergovernmental organisations; the second goal is to apply International Relations (IR) theories to explain the growing diversity, overlap and fragmentation of international organisations dealing with CCS. Which international organisations embrace CCS, and which refrain from discussing it at all? What role do these institutions play in bringing CCS forward? Why is international collaboration on CCS so fragmented and weak? We utilise realism, liberal institutionalism and constructivism to provide three different interpretations of the complex global landscape of CCS governance in the context of the similarly complicated architecture of global climate policy. A realist account of CCS's fragmented international politics is power driven. International fossil fuel and energy organisations, dominated by major emitter states, take an active role in CCS. An interest-based approach, such as liberal institutionalism, claims that CCS is part of a “regime complex” rather than an integrated, hierarchical, comprehensive and international regime. Such a regime complex is exemplified by the plethora of international organisations with a role in CCS. Finally, constructivism moves beyond material and interest-based interpretations of the evolution of the institutionally fragmented architecture of global CCS governance. The 2005 IPCC Special Report on CCS demonstrates the pivotal role that ideas, norms and scientific knowledge have played in transforming the preferences of the international climate-change policy community.     

Time and temperature dependency of carbon dioxide triggered metal(loid) mobilization in soil

Assessing the influence of CO₂ on soil and aquifer geochemistry is a task of increasing interest when considering risk assessment for geologic carbon sequestration. Leakage and CO₂ ascent can lead to soil acidification and mobilization of potentially toxic metals and metalloids due to desorption or dissolution reactions. We studied the CO₂ influence on an Fe(III) (oxyhydr)oxide rich, gleyic Fluvisol sampled in close vicinity to a Czech mofette site and compared the short-term CO₂ influence in laboratory experiments with observations on long-term influence at the natural site. Six week batch experiments with/without CO₂ gas flow at 3 different temperatures and monitoring of liquid phase metal(loid) concentrations revealed two main short-term mobilization processes. Within 1 h to 1 d after CO₂ addition, mobilization of weakly adsorbed metal cations occurred due to surface protonation, most pronounced for Mn (2.5–3.3 fold concentration increase, mobilization rates up to 278 ± 18 μg Mn kg_soil⁻¹ d⁻¹) and strongest at low temperatures. However, total metal(loid) mobilization by abiotic desorption was low. After 1–3 d significant Fe mobilization due to microbially-triggered Fe(III) (oxyhydr)oxide dissolution began and continued throughout the experiment (up to 111 ± 24 fold increase or up to 1.9 ± 0.6 mg Fe kg_soil⁻¹ d⁻¹). Rates increased at higher temperature and with a higher content of organic matter. The Fe(III) mineral dissolution was coupled to co-release of incorporated metal(loid)s, shown for As (up to 16 ± 7 fold, 11 ± 8 μg As kg_soil⁻¹ d⁻¹). At high organic matter content, re-immobilization due to resorption reactions could be observed for Cu. The already low pH (4.5–5.0) did not change significantly during Fe(III) reduction due to buffering from sorption and dissolution reactions, but a drop in redox potential (from > +500 mV to minimum +340 ± 20 mV) occurred due to oxygen depletion. We conclude that microbial processes following CO₂ induction into a soil can contribute significantly to metal(loid) mobilization, especially at optimal microbial growth conditions (moderate temperature, high organic carbon content) and should be considered for carbon sequestration monitoring and risk assessment.     

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。     

碳捕获和封存技术认知、政策现状与减排潜力分析

在综合大量相关资料的基础上,研究总结了碳捕获和封存（CCS）技术的发展现状、示范项目进展和相关的国际法规政策,分析了其大规模应用的障碍,并将CCS技术与提高能效、发展可再生能源等减排技术方案进行了对比。分析认为,一方面我国需审慎评估CCS技术推广使用可能产生的负面影响;另一方面我国也需要适当加大对CCS关键技术的研发投入,避免在技术上受制于人。此外,有关CCS推广的财税政策的推出,需要视CCS技术的实际发展情况而定。我国还需要根据现实情况,重点考虑如何对现有火电厂进行改造,为CCS技术未来的大规模推广打下基础。