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

该项目第二阶段的目标是进一步的实验研究和模型开发，研究在高温高压条件下，碳酸盐岩为基质的多孔介质与反应气体(如二氧化碳)相互作用时的光谱复合电学性质。为此，我们继续在德州大学弗莱贝格分校与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。来自柏林理工大学和巴塞罗那大学的研究人员支持这一项目。碳酸盐岩储集层因为拥有巨大的石油和天然气资源而受到关注，因此也是提高石油采收率和二氧化碳封存努力的目标。然而，碳酸盐岩由于其极不均匀的孔隙空间和碳酸盐基质的活性性质，给地球科学带来了巨大的挑战。电磁(EM)方法已被证明是非常有价值的监测技术，因为它们对孔隙含量特别敏感。尽管硅质和碳酸盐岩储层的监测任务是相同的，但对碳酸盐岩电性的岩石物理知识仍然相当粗糙。在第一阶段的项目中，我们全面论证和系统地研究了固体和破碎碳酸盐岩的岩石物理性质。我们对碳酸盐岩高压反应动力学有了基本的系统认识和必要的工具。已经检索到的巨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。基于这些结果，我们选择了合适的碳酸盐和颗粒大小，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实验室条件下观察到的效果，使用谱激发极化(SIP)方法和高压磁悬浮天平在15°C到70°C和0.5到30兆帕之间的高压磁悬浮天平进行反应动力学测量。低压/低温状态覆盖浅层含水层，高压/温度状态代表2500-3000米以下的储集层。最后，我们致力于建立二氧化碳和储层条件下碳酸盐岩表面长期蚀变过程中表面反应与反应动力学之间的基于模型的关系。整个项目将为基本理解碳酸盐中的表面反应以及活性气体(尤其是二氧化碳)与活性岩石基质的相互作用提供重要的数据。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，重点放在电化学相互作用、它们的电学表现和模型描述上。这也允许使用EM方法评估碳酸盐岩储集层的监测选择。

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.