Viscoelastic surfactants (VES) are often used as viscous diverters in acidizing stimulation to prolong the acid consumption time and maximize zonal coverage of the acid for improving well productivity. However, the ceiling temperature of commercial VES cannot exceed 120 °C in practical use because of the poor thermal stability and fragile molecular structure, hindering their implementation in high-temperature oil reservoirs, i.e., ≥150 °C. Here we synthesized a novel C-tailed diamine, -erucaminopropyl--dimethylamine (EDPA), and examined comparatively its rheological behavior, assemblies morphology and molecular stability in 20 wt% HCl with a commercial VES, erucyl dimethyl amidopropyl betaine (EDAB). The feasibility of EDPA for acidizing stimulation was assessed by acid etching of carbonate rock with its HCl solution at 150 °C. Rheological results showed that the 2.5 wt% EDPA–20 wt% HCl solution maintains stable viscosity of 90 mPa s at 150 °C for 60 min, while that of 2.0 wt% EDAB HCl solution is just 1 mPa s under identical conditions. H NMR spectra and cryo-TEM observations revealed that the chemical structure and self-assembled architectures of EDPA remained intact in such context, but the EDAB suffered from degradation due to the hydrolysis of the amide group, accounting for the poor heat-resistance and acid-tolerance. The reaction rate of 2.5 wt% EDPA HCl solution with carbonate rock was one order of magnitude lower than that of 20 wt% HCl solution at 150 °C, underpinning the potential of EDPA to be used in the high-temperature reservoirs acidizing. This work improved the thermal tolerance of VES in highly concentrated HCl solution, paving a feasible way for the acidization of high-temperature reservoir environments (∼150 °C).

中文翻译：

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一种坚固的粘弹性表面活性剂，可耐受高达 150 °C 的 20% HCl，用于油井增产

粘弹性表面活性剂（VES）通常在酸化增产中用作粘性分流剂，以延长酸消耗时间并最大化酸的层位覆盖，从而提高油井产能。然而，由于热稳定性差和分子结构脆弱，商用VES在实际使用中的上限温度不能超过120℃，阻碍了其在高温油藏中的实施，即≥150℃。在此，我们合成了一种新型 C 尾二胺，芥子氨基丙基二甲胺 (EDPA)，并与商业 VES 芥基二甲基酰胺丙基甜菜碱 (EDAB) 比较了其在 20 wt% HCl 中的流变行为、组装形态和分子稳定性。通过在 150 °C 的 HCl 溶液中对碳酸盐岩进行酸蚀，评估了 EDPA 用于酸化增产的可行性。流变学结果表明，2.5 wt% EDPA–20 wt% HCl 溶液在 150 °C 下保持 60 分钟稳定的粘度为 90 mPa s，而 2.0 wt% EDAB HCl 溶液在相同条件下仅为 1 mPa s。H NMR 谱和冷冻 TEM 观察表明，EDPA 的化学结构和自组装结构在这种情况下保持完整，但 EDAB 由于酰胺基团的水解而遭受降解，导致其耐热性和耐酸性较差。 -宽容。在 150 ℃ 下，2.5 wt% EDPA HCl 溶液与碳酸盐岩的反应速率比 20 wt% HCl 溶液低一个数量级，增强了 EDPA 在高温油藏酸化中的应用潜力。这项工作提高了VES在高浓度HCl溶液中的耐热性，为高温油藏环境（~150℃）的酸化铺平了可行的途径。