Natural gas, the largest source for electricity generation in the US, is produced via hydraulic fracturing. Fracturing uses water mixed with chemical additives to free natural gas from the shale formation. While downhole, these fluids contact small formation particles produced during well-perforation and remain in contact with the particles until the fluids return to the well surface. We performed experiments to investigate the physical and chemical interactions between Marcellus shale particles and fluid at high temperature (80 °C). The treatments in this study include incubating shale particles in solutions containing individual organic and inorganic additives used during fracturing (hydrochloric acid, persulfate, LEB-10X, WGA, FRS, Revert Flow (RF), and BXL). The particles exhibited a measurable influence on flowback fluid chemistry when treated with chemical additives. An optimized methodology was developed for laser-based Particle Size Analysis (PSA) with a wet-dispersion unit, which was then used to measure changes in particle size after treatment. The PSA results indicate that mixing speeds >2800 rpm can cause particle breakage and low speeds are required for PSA of shales. We observed no difference in particle size across treatments after incubation, indicating that clay swelling likely occurs during incubation. The influence of contact time was investigated for the inorganic treatments (persulfate and HCl containing treatments) given that these treatments resulted in higher concentrations of element release and precipitation compared to the organics additives tested. The results show that contact time is an essential consideration in shale transformation studies. Our findings link changing water chemistry to specific fracturing additives and provide key information for understanding the fluid-rock interactions.

天然气是美国最大的发电来源，它是通过水力压裂生产的。压裂使用混合了化学添加剂的水将页岩层中的天然气释放出来。在井下时，这些流体与在射孔过程中产生的小地层颗粒接触，并保持与颗粒接触，直到流体返回井表面为止。我们进行了实验，以研究高温（80°C）下Marcellus页岩颗粒与流体之间的物理和化学相互作用。这项研究中的处理方法包括在包含压裂过程中使用的有机和无机添加剂（盐酸，过硫酸盐，LEB-10X，WGA，FRS，回流（RF）和BXL）的溶液中培养页岩颗粒。当用化学添加剂处理时，这些颗粒对回流流体的化学性质具有可测量的影响。针对带有湿分散单元的基于激光的粒度分析（PSA），开发了一种优化的方法，然后将其用于测量处理后的粒度变化。PSA结果表明，> 2800 rpm的混合速度可能会导致颗粒破裂，而页岩的PSA需要低速。我们观察到孵育后各处理的粒径没有差异，表明在孵育过程中可能发生粘土溶胀。考察了接触时间对无机处理（过硫酸盐和含HCl的处理）的影响，因为与所测试的有机物添加剂相比，这些处理导致元素释放和沉淀的浓度更高。结果表明，接触时间是页岩转化研究中必不可少的因素。我们的发现将不断变化的水化学与特定的压裂添加剂联系在一起，并为了解流体-岩石相互作用提供了重要信息。