Carbon dioxide (CO₂) as supercritical (scCO₂) or foamed (CO₂-Foam) fluid has been tested many times as a fracturing fluid, though it has not yet proven viable. Many challenges have been identified with scCO₂ as a fracturing fluid, including poor additive solubility, low viscosity, and limited accessibility. However, CO₂ is known to adsorb to organic matter (OM) and displace methane (i.e., enhanced coal bed methane [ECBM] operations), or to mobilize oil as in tertiary enhanced oil recovery. In this study we augment the efficacy of the kerogen control fluid (KCF) for stimulating unconventional rock formations by alternating aqueous oxidizing fracturing fluid with CO₂ injection or by combining oxidizers directly with CO₂ as a new additive. To this end, KCF-CO₂ tests were designed to treat OM and extend the depth of permeability enhancement. We report the first attempt to combine oxidizer with CO₂ in the presence of source shale rocks at elevated temperature and pressure. Scanning electron microscopy imaging of the treated shale sample surfaces demonstrate potential porosity and permeability enhancement, though some mineral and organic deposits are also observed, which may prove to be detrimental. Meanwhile, alternating water-based KCF with CO₂ provides a potential improvement to the KCF as predicted by early lab results on OM. The KCF-CO₂ concept has no equivalent to date in unconventional hydraulic fracturing operations. This technology will contribute to reducing the footprint of anthropogenic CO₂ and enhancing its permanent sequestration in unconventional stimulated reservoirs, compliant with our global clean energy initiative of carbon capture, utilization, and storage.

中文翻译：

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氧化剂-CO2系统对水力压裂非常规烃源岩的化学力学影响

作为超临界 ( scCO ₂ ) 或泡沫 (CO ₂ -Foam) 流体的二氧化碳 (CO ₂ )已作为压裂液进行了多次测试，尽管尚未证明它是可行的。_{使用 scCO 2}作为压裂液已经确定了许多挑战，包括添加剂溶解度差、粘度低和可及性有限。然而，众所周知，CO ₂会吸附到有机物 (OM) 上并置换甲烷（即强化煤层气 [ECBM] 操作），或者在三次强化采油中使石油流动。_{在这项研究中，我们通过将含水氧化压裂液与 CO 2}交替来提高干酪根控制液 (KCF) 对非常规岩层的刺激效果注入或通过将氧化剂直接与作为新添加剂的 CO _2结合。为此，设计了 KCF-CO ₂试验来处理 OM 并延长渗透增强的深度。我们报告了在高温高压下源页岩存在的情况下将氧化剂与 CO ₂结合的首次尝试。处理过的页岩样品表面的扫描电子显微镜成像显示潜在的孔隙度和渗透率增强，尽管也观察到一些矿物和有机沉积物，这可能被证明是有害的。同时，正如早期实验室对 OM 的结果所预测的，将水基 KCF 与 CO _{2交替提供了对 KCF 的潜在改进。}KCF-CO ₂迄今为止，在非常规水力压裂作业中，这一概念尚无等效。该技术将有助于减少人为 CO ₂的足迹并增强其在非常规增产储层中的永久封存，符合我们的碳捕获、利用和储存的全球清洁能源倡议。