Spectral Induced Polarization of Carbonates during Exposure to Reactive Gases under Reservoir Conditions (part II)

该项目的第二阶段的目标是在高压和高温下与反应气体（如CO2）相互作用时，对含碳酸盐岩石基质的多孔介质的光谱复杂电学特性进行进一步的实验研究和模型开发。为此目的，我们继续在弗莱堡工业大学地球物理学家和工艺工程师的良好合作下进行基础实验室研究。来自柏林工业大学和巴塞罗那大学的研究人员支持该项目。碳酸盐岩储层由于拥有丰富的石油和天然气资源而成为人们关注的焦点，因此也是提高石油采收率和二氧化碳封存的目标。然而，由于碳酸盐孔隙空间极不均匀，且碳酸盐基质具有反应性，因此对地球科学提出了巨大的挑战。由于电磁（EM）方法对孔隙含量特别敏感，因此已被证明是一种具有重要价值的监测技术。尽管硅质储层和碳酸盐储层的监测任务是相同的，但关于碳酸盐储层电性的岩石物理知识仍然相当粗糙。在项目的第一阶段，我们对固体和破碎碳酸盐岩的岩石物理性质进行了全面的论证和系统的研究。我们已经对碳酸盐岩的高压反应动力学有了基本的系统理解和必要的工具。已经检索到的庞大数据集允许评估孔隙空间和表面性质对碳酸盐电导率的影响。根据这些结果，我们选择了合适的碳酸盐和粒度，并按计划开始了高压实验。在第二个项目阶段，我们将继续系统地研究在实验室条件下观察到的效果，使用光谱诱导极化（SIP）方法和高压磁悬浮天平在温度为15°C至70°C，压力为0.5至30 MPa时的反应动力学测量。低压/低温状态覆盖浅层含水层，高压/高温状态代表2500 - 3000米深度的储层。最后，我们的目标是在二氧化碳和储层条件下建立碳酸盐岩长期地表蚀变过程中SIP与反应动力学之间的模型关系。整个项目将为了解碳酸盐岩中的SIP以及活性气体（特别是CO2）与活性岩石基质的相互作用提供重要数据。由于我们使用破碎样品的独特方法，我们降低了系统的复杂性，并专注于电化学相互作用，它们的电气表现和模型描述。这也允许在碳酸盐岩储层中使用电磁方法评估监测方案。

The aim of the second phase of this project is the further experimental investigation and the model development of the spectral complex electrical properties of porous media with a carbonatic rock matrix during interaction with reactive gases (e.g. CO2) at elevated pressure and temperature. For this purpose, we continue to conduct a fundamental laboratory study in a well-proven cooperation of geophysicists and process engineers at the TU Freiberg. Researchers from the TU Berlin and the University of Barcelona support the project.Carbonatic reservoirs have come into focus since they host huge resources of oil and natural gas and, consequently, are also targets for enhanced oil recovery EOR and carbon dioxide sequestration endeavors. However, carbonates provide great challenges to the geosciences due to their extremely heterogeneous pore space and the reactive nature of the carbonatic matrix. Electromagnetic (EM) methods have proven to be of great value as monitoring techniques as they are specifically sensitive to the pore content. Although the monitoring tasks involved are the same for both siliceous and carbonatic reservoirs, the petrophysical knowledge of the electrical properties of carbonates is still rather crude.During the first phase of the project, we have overall demonstrated and systematically investigated the petrophysical properties of solid and crushed carbonate rocks. We have developed a fundamental system understanding and the necessary tools to tackle the high pressure reaction kinetics of carbonate rocks. The already retrieved huge data set allows for assessing the influence of pore space and surface properties on the electrical conductivity of carbonates. Based on these results we chose a suitable carbonate and particle size and started the high-pressure experiments as planned.In the second project phase we will continue to systematically investigate the observed effects under laboratory conditions using the spectral induced polarization (SIP) method and reaction kinetics measurements with a high-pressure magnetic suspension balance at temperatures between 15°C and 70°C and pressures between 0.5 and 30 MPa. The low pressure/ low temperature regime covers shallow aquifers, high pressure/ temperature regimes represent reservoirs down to 2500 – 3000 m depth. Finally we aim at the development of a model-based relation between SIP and reaction kinetics during long-term surface alteration for carbonates under CO2 and reservoir conditions.The overall project will contribute important data to the fundamental understanding of SIP in carbonates and the interaction of reactive gases (especially CO2) with reactive rock matrices. Due to our unique approach of using crushed samples we reduce the complexity of the system and focus on the electro-chemical interactions, their electrical manifestation, and model description. This also allows for the assessment of monitoring options with EM methods in carbonatic reservoirs.