Injected CO₂ streams may have geochemical reactivity to different rock types in a CO₂ storage complex depending on solubility and formation water chemistry. The Precipice Sandstone and Evergreen Formation are a low-salinity reservoir–seal pair in the Surat Basin, Australia, targeted for potential CO₂ storage. The kinetic geochemical CO₂ reactivity of different rock facies from three regions were predicted over 30 and 1000 year time periods. No material CO₂ mineral trapping in the quartz-rich Precipice Sandstone reservoir was predicted, owing to the low rock reactivity. Predicted CO₂ mineral trapping in the Evergreen Formation was more variable due to different amounts of more reactive feldspars, clays, calcite and siderite. Predicted mineral trapping as siderite and ankerite was between 0.03 and 8.4 kg m^–3 CO₂, and mainly depends on chlorite and plagioclase content. Predicted pH was between 5 and 7.5 after 1000 years. Pyrite precipitation was also predicted with SO₂ present in the injectate. QEMSCAN and SEM-EDS (scanning electron microscopy and energy-dispersive spectroscopy) spot imaging of samples from the seal containing natural fractures filled by siderite, pyrite, clays, ankerite, calcite, barite and apatite represent a natural analogue for natural mineral trapping. These are in good agreement with our model predictions. This study suggests that, from a geochemical perspective, the Precipice Sandstone is a suitable storage reservoir, whereas mineral trapping would occur in the overlying Evergreen Formation.

Supplementary material: Additional model inputs, characterization and model images, and an excel file of QEMSCAN mineral and porosity components, are available at https://doi.org/10.6084/m9.figshare.c.5395393

Thematic collection: This article is part of the Geoscience for CO₂ storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

取决于溶解度和地层水化学性质，注入的CO ₂物流可能对CO ₂储存复合物中的不同岩石类型具有地球化学反应性。悬崖砂岩和常绿地层是澳大利亚苏拉特盆地的一个低盐度储层-密封层，其目标是潜在的CO ₂储存。在30年和1000年的时间段内，预测了三个地区不同岩石相的动力学地球化学CO ₂反应性。由于岩石的低反应性，没有预测到在富含石英的Precipice砂岩储层中有任何CO ₂矿物的捕集。预测的CO ₂由于不同数量的更具活性的长石，粘土，方解石和菱铁矿，常绿组中的矿物捕获更具可变性。预测的矿物捕获为菱铁矿和方铁矿为0.03至8.4 kg m ^–3 CO ₂，并且主要取决于亚氯酸盐和斜长石含量。1000年后，预计的pH值在5至7.5之间。还用SO ₂预测了黄铁矿的沉淀存在于注射剂中。QEMSCAN和SEM-EDS（扫描电子显微镜和能量色散光谱）对来自海豹的样品进行斑点成像，其中包含由菱铁矿，黄铁矿，粘土，方铁矿，方解石，重晶石和磷灰石填充的天然裂缝，代表了天然矿物捕集的天然类似物。这些与我们的模型预测非常吻合。这项研究表明，从地球化学的角度来看，悬崖砂岩是一个合适的储集层，而矿物捕获将发生在上覆的常绿地层中。

补充材料： https://doi.org/10.6084/m9.figshare.c.5395393提供了附加的模型输入，特征和模型图像以及QEMSCAN矿物和孔隙度成分的excel文件。

专题收集：本文是可用于以下位置的Geoscience for CO ₂储存集合的一部分：https://www.lyellcollection.org/cc/geoscience-for-co2-storage