Microanalysis of natural and engineered CO2 mineralisation at CarbFix2 site, Iceland

冰岛 CarbFix2 站点天然和工程二氧化碳矿化的微量分析

• 批准号: 2425483
• 金额: --
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2425483
• 关键词: Microanalysis; natural; engineered; CO2; mineralisation

CO2 capture and storage (CCS) is the only industrial scale technology that can directly reduce the CO2 emissions produced by the combustion of fossil fuels or industrial process emissions. Given global reliance on fossil fuels for energy and industrial manufacturing needs, CCS is an essential technology for the global drive to reach net zero CO2 emissions to the atmosphere4. The success of geologic CO2 storage critically depends on the long-term security of the storage site. Buoyant gas phase CO2 stored in sedimentary reservoirs requires long duration monitoring of storage. Alternatively, secure storage can be guaranteed through the permanent conversion of injected CO2 into new carbonate minerals within the storage site.Several tests of the sequestration that occurs when CO2 is injected into reactive basalts have recently been undertaken, notably the CarbFix1 project, located at the Hellisheidi geothermal field in Iceland[1]. Measurements of dissolved inorganic carbon and tracers injected with the CO2 indicate that mineralisation of >95 % of the injected CO2 (175 tonnes) was achieved within two years1. However, feasibility of the method at an industrial scale is still uncertain, as the key question of how long viable injectivity can be maintained is unknown. To address this question, the CarbFix2 experiment was launched in 2014, and currently 10,000 tonnes of CO2 and 5,000 tonnes of H2S are being injected per year into the geothermal field[2]Key research questions:-Identify where natural CO2 mineralisation has occurred in the field prior to injection based on observations made during drilling and tracer tests by Reykjavik Energy.-Resolve the conditions under which natural CO2 precipitation took place during growth of individual crystals using world-class microbeam analysis and geochemical modelling.-Establish baseline geochemical fingerprints prior to engineered injection of CO2 and H2S-Identify isotopic signatures of CarbFix1 carbonates from downhole samples.-Undertake field visit to surface exposures of natural analogues. Well-studied Jurassic ophiolite complexes in Liguria (Italy) host ophicalcites of carbonate mineralised ocean floor, which provide spatial information and constraints on the preservation of mineralisation pathways and geochemical fingerprints over time.-Reproduce the mineralization process on downhole cutting samples experimentally and image it with synchrotron-based X-ray microtomograph. From these experiments, dissolution and re-precipitation of minerals will be mapped and quantified.-4D microtomography experiments, varying temperature and salinity, will assess if CO2 mineralisation can be enhanced through purposeful injection strategies into hotter or colder parts of the reservoir with changed brine salinity.Methodology and timetable:This project will utilise the world-class ion microprobe (SIMS) instruments within the School of GeoSciences (Cameca 1270 and new Cameca IMS 7f-geo). You will make micro-analytical traverses across individual crystals from borehole cuttings and from mineralised basalt core samples. The micrometre growth zones within each crystal, like the rings on a tree, record the isotope and trace element signatures of porewater during the crystal growth. The growth duration, temperature, CO2 and water origins of natural carbonates will be reconstructed.These analyses will be complemented by mineralisation experiments in a novel x-ray transparent reaction cell that allows monitoring fluid-rock interaction with time-resolved synchrotron x-ray microtomography. These will use downhole cuttings samples to directly map and quantify dissolution and re-precipitation of minerals at reservoir conditions[3]. The knowledge generated will be used to ascertain how CO2 mineralisation can be enhanced through varied injection strategies and inform how to accurately incorporate such controls into predictive models of CO2 mineralisation in this reservoir.

二氧化碳捕集与封存（CCS）是唯一可以直接减少化石燃料燃烧或工业过程排放产生的二氧化碳排放的工业规模技术。鉴于全球能源和工业制造需求对化石燃料的依赖，CCS 是全球实现大气二氧化碳净零排放的一项重要技术4。二氧化碳地质封存的成功关键取决于封存地点的长期安全。储存在沉积物储层中的浮力气相二氧化碳需要长期监测储存。或者，可以通过将注入的二氧化碳永久转化为封存地点内的新碳酸盐矿物来保证安全封存。最近对将二氧化碳注入活性玄武岩时发生的封存进行了多项测试，特别是位于位于冰岛Hellisheidi地热田[1]。对注入 CO2 的溶解无机碳和示踪剂的测量表明，注入的 CO2（175 吨）的 95% 以上在两年内实现了矿化1。然而，该方法在工业规模上的可行性仍不确定，因为可行的注入能力能够维持多长时间的关键问题尚不清楚。为了解决这个问题，CarbFix2 实验于 2014 年启动，目前每年向地热田注入 10,000 吨 CO2 和 5,000 吨 H2S[2]关键研究问题：-确定在地热田中发生天然 CO2 矿化的位置根据雷克雅未克能源公司在钻探和示踪剂测试期间进行的观察，在注入之前对现场进行了分析。-解决了在生长过程中发生自然二氧化碳沉淀的条件使用世界一流的微束分析和地球化学建模来分析单个晶体。-在工程注入 CO2 和 H2S 之前建立基线地球化学指纹-从井下样品中识别 CarbFix1 碳酸盐的同位素特征。-对天然类似物的表面暴露进行实地考察。利古里亚（意大利）经过充分研究的侏罗纪蛇绿岩杂岩含有碳酸盐矿化海底的蛇绿岩，这为矿化路径和地球化学指纹随时间的推移提供了空间信息和约束。-通过实验重现井下切割样品的矿化过程并对其进行成像基于同步加速器的 X 射线显微断层扫描仪。通过这些实验，将绘制和量化矿物质的溶解和再沉淀。-4D 显微断层扫描实验（不同的温度和盐度）将评估是否可以通过有目的地将改变的盐水注入储层较热或较冷的部分来增强二氧化碳矿化方法和时间表：该项目将利用地球科学学院世界一流的离子微探针（SIMS）仪器（Cameca 1270 和新的 Cameca IMS 7f-地理）。您将对钻孔钻屑和矿化玄武岩岩心样本中的单个晶体进行微观分析。每个晶体内的微米生长区域，就像树上的年轮一样，记录了晶体生长过程中孔隙水的同位素和微量元素特征。天然碳酸盐的生长持续时间、温度、二氧化碳和水来源将被重建。这些分析将通过新型 X 射线透明反应池中的矿化实验进行补充，该反应池允许通过时间分辨同步加速器 X 射线显微断层扫描监测流体-岩石相互作用。这些将使用井下岩屑样本来直接绘制和量化储层条件下矿物的溶解和再沉淀[3]。所产生的知识将用于确定如何通过不同的注入策略来增强二氧化碳矿化，并告知如何准确地将此类控制纳入该储层二氧化碳矿化的预测模型中。