Creep of CarbFix basalt: influence of rock–fluid interaction
Creep of CarbFix basalt: influence of rock–fluid interaction
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DOI：
10.5194/se-13-137-2022
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发表时间：
2022-01
期刊：
影响因子：
3.4
通讯作者：
Tiange Xing;H. Ghaffari;U. Mok;M. Peč
中科院分区：
文献类型：
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作者：
Tiange Xing;H. Ghaffari;U. Mok;M. Peč
抽象的。地质固碳提供了永久的CO2储存，以缓解目前大气中CO2的高浓度。玄武岩中的CO2矿化已被证明是最安全的储存选择之一。为了成功地实施和未来的改进，这项技术，在反应流体的存在下，储层岩石的时间依赖性变形行为需要详细研究。我们进行了负载步进蠕变实验玄武岩从CarbFix网站（冰岛）在几个孔隙流体条件（干燥，H2O饱和和H2O + CO2饱和）在温度，T = 80 ℃和有效压力，Peff=50 MPa，在此期间，我们收集了机械，声学和孔隙流体化学数据。我们观察到在低至失效强度11%的应力下的瞬时蠕变。声发射（AE）与应变积累强烈相关，表明蠕变变形是一个脆性的过程，与显微组织观察。AE的发生率和幅度在液体饱和实验中高于干燥条件。我们推断，蠕变变形的主要机制是时间和应力依赖的亚临界裂纹。我们的研究结果表明，含水流体的存在下发挥一阶控制玄武质岩石的蠕变变形，而流体的组成只起次要作用的研究条件下。
Abstract. Geological carbon sequestration provides permanent CO2 storage to mitigate the current high concentration of CO2 in the atmosphere. CO2 mineralization in basalts has been proven to be one of the most secure storage options. For successful implementation and future improvements of this technology, the time-dependent deformation behavior of reservoir rocks in the presence of reactive fluids needs to be studied in detail. We conducted load-stepping creep experiments on basalts from the CarbFix site (Iceland) under several pore fluid conditions (dry, H2O saturated and H2O + CO2 saturated) at temperature, T≈80 ∘C and effective pressure, Peff=50 MPa, during which we collected mechanical, acoustic and pore fluid chemistry data. We observed transient creep at stresses as low as 11 % of the failure strength. Acoustic emissions (AEs) correlated strongly with strain accumulation, indicating that the creep deformation was a brittle process in agreement with microstructural observations. The rate and magnitude of AEs were higher in fluid-saturated experiments than in dry conditions. We infer that the predominant mechanism governing creep deformation is time- and stress-dependent subcritical dilatant cracking. Our results suggest that the presence of aqueous fluids exerts first-order control on creep deformation of basaltic rocks, while the composition of the fluids plays only a secondary role under the studied conditions.