Large amounts of aqueous-based fluids used in hydraulic fracturing of tight formations are not fully recovered immediately after treatment, resulting in increased water saturation, water blockage, clay swelling, reduced relative permeability, and long-lasting formation damage that impedes production. To enhance flowback fluid recovery, nano-emulsion based flowback aids were developed for oil-bearing sandstone and carbonate formations. The flowback aids were formulated using a blend of high-temperature stable ester-based solvents, alcohols, and surfactants to form optically clear nano-emulsions. All the developed flowback aids demonstrated low surface tension (22–30 mN/m) and interfacial tension (<6 mN/m), which is necessary for reducing capillary pressure. The particle size of the nano-emulsions was found to be 5–15 nm. The flowback aids were able to prevent the formation of the emulsion with crude oil. It has been found that nano-emulsions formulated using non-ionic and anionic surfactants worked better for sandstone, whereas non-ionic and cationic surfactant-based formulations worked better for carbonate. These formulations not only provide quick aqueous fluid displacement in column tests but also greatly enhance the rate of oil flow in core flow experiments conducted with broken slickwater fracturing fluids. It was determined that in the absence of a flowback aid, the regained permeability was around 40%, whereas with flowback aids it was increased to 65%–75%. The paper demonstrates the effectiveness of flowback enhancers to quickly recover the injected aqueous fracturing fluid, thereby reducing water saturation, which in turn enhances productivity, and shows the benefit of applying chemistry for low permeability oil reservoirs.

中文翻译：

---

通过独特的回流化学增强致密砂岩和碳酸盐油藏的恢复渗透率和流体回流

致密地层水力压裂中使用的大量水基流体在处理后没有立即完全恢复，导致含水饱和度增加、堵水、粘土膨胀、相对渗透率降低和长期地层损害，阻碍生产。为了提高返排液采收率，针对含油砂岩和碳酸盐地层开发了基于纳米乳液的返排助剂。使用高温稳定的酯基溶剂、醇和表面活性剂的混合物配制回流助剂，以形成光学透明的纳米乳液。所有开发的回流助剂都表现出低表面张力（22-30 mN/m）和界面张力（<6 mN/m），这是降低毛细管压力所必需的。发现纳米乳液的粒径为 5-15 nm。回流助剂能够防止与原油形成乳液。已经发现，使用非离子和阴离子表面活性剂配制的纳米乳液对砂岩效果更好，而基于非离子和阳离子表面活性剂的配方对碳酸盐效果更好。这些配方不仅在柱测试中提供快速的水流体驱替，而且在使用破碎的滑溜水压裂液进行的岩心流动实验中大大提高了油的流动速率。经测定，在没有返排助剂的情况下，重新获得的渗透率约为 40%，而在使用返排助剂的情况下，它增加到 65%–75%。该论文展示了返排增强剂在快速回收注入的含水压裂液方面的有效性，从而降低了水饱和度，从而提高了生产率，