To evaluate the effectiveness of the acidic and oxidation reactions of stimulating organic-rich shale during fracturing, we conducted imbibition experiments using the oxidant (Na₂S₂O₈), under no confining pressure conditions. The chemical-induced fracturing process of Na₂S₂O₈ with Marcellus shale samples was tested and evaluated by these methods: the mass changes before and after imbibition tests were measured; mineral phase alternation and total organic carbon (TOC) before and after Na₂S₂O₈ aqueous solutions treatment were measured, and the initiation and propagation of induced fractures, the bubble density and pH changes of the Na₂S₂O₈ solutions were monitored. Results show that pervasive macro-fractures formed in response to acidic and oxidative dissolutions. The decrease of calcite, illite, pyrite, and TOC content after different concentrations of Na₂S₂O₈ treatments verified that these components reacted with Na₂S₂O₈ aqueous solutions. Na₂S₂O₈ reacted with calcite (CaCO₃), dolomite (CaMg(CO₃)₂ and illite through “acidic dissolution”. Besides, Na₂S₂O₈ reacted with OM and pyrite through oxidation to form CO₂ as well. The combined effect of acidic and oxidation reactions caused the fracture initiation and propagation, where the acidic reaction of calcite was dominant while oxidation reactions were secondary. Gypsum (CaSO₄⸱2H₂O) crystallization was formed after Na₂S₂O₈ imbibition and the crystallization-induced stress was one of the favorable reasons to initiate the chemical-induced fractures. Compared with HCl, Na₂S₂O₈ has improvements on the chemical-induced fracturing of Marcellus shale samples. The results indicate that adding Na₂S₂O₈ with a proper concentration in hydraulic fracturing fluids has favorable potential to enhance the recovery of oil and gas for organic-rich shale through initiating chemical-induced fractures.

为了评估压裂过程中富集有机页岩的酸性和氧化反应的有效性，我们在无限制压力条件下使用氧化剂（Na ₂ S ₂ O ₈）进行了吸水实验。用这些方法测试和评估了Na ₂ S ₂ O ₈与Marcellus页岩样品的化学诱导压裂过程：测量了吸水试验前后的质量变化；Na ₂ S ₂ O ₈之前和之后的矿物相变和总有机碳（TOC）测量了水溶液的处理量，并监测了诱发裂缝的产生和扩展，Na ₂ S ₂ O ₈溶液的气泡密度和pH变化。结果表明，普遍的大裂缝是在酸性和氧化溶解作用下形成的。不同浓度的Na ₂ S ₂ O ₈处理后方解石，伊利石，黄铁矿和TOC含量的减少证明了这些成分与Na ₂ S ₂ O ₈水溶液反应了。Na ₂ S ₂ O ₈与方解石（CaCO ₃），白云石（CaMg（CO ₃）₂和伊利石通过“酸性溶解”。此外，Na ₂ S ₂ O ₈与OM和黄铁矿也通过氧化反应生成CO ₂。断裂的萌生和扩展，其中方解石的酸性反应占主导地位，而氧化反应是次要的。石膏（硫酸钙₄ ⸱2H ₂ O）结晶用Na后形成₂小号₂ ö ₈吸液和结晶引起的应力是有利的一个化学性骨折的原因与氯化钠相比₂ S ₂ O ₈改善了Marcellus页岩样品的化学诱导压裂。结果表明，在水力压裂液中添加适当浓度的Na ₂ S ₂ O ₈，具有良好的潜力，可通过引发化学诱导的裂缝来提高富含有机物的页岩的油气采收率。