适用于低渗透高盐油藏的醇醚磺酸盐与甜菜碱表面活性剂复配增注体系

Compound Injection System of Alcohol Ether Sulfonate and Betaine Surfactant for Reservoirs with Low Permeability and High Salinity

张国庆 龚卓婷 易 晓 王正良 郑延成

ZHANG Guoqing GONG Zhuoting YI Xiao WANG Zhengliang ZHENG Yancheng

低渗油藏具有孔喉半径小、渗透能力低、吸水能力差等特点，导致化学驱油效果不理想。针对该问题，在十 二醇中引入环氧丙烷和环氧乙烷，并经磺化得到醇醚磺酸盐（DP6E6S），构建了DP6E6S与C16羧基甜菜碱（PNC） 表面活性剂的复配体系，评价了该体系的表/界面性能、老化性、吸附性、润湿性和乳化性能，并通过岩心流动实 验研究了复配体系的增注性能。结果表明，PNC与DP6E6S具有较强的协同作用，与单一表面活性剂相比，可以 有效降低临界胶束浓度和表面张力，提高乳液的稳定性和抗吸附性能。PNC与DP6E6S复配物质的量比为1∶1 和2∶3的表面活性剂体系具备较强的抗老化性能，能在较宽的盐度范围（5%～10%）内将油水界面张力维持至 10-3 mN/m，在60 ℃下老化30 d后的油水界面张力无明显变化。随着盐度增加，由复配表面活性剂制得的乳液会 经历从Winsor I到Winsor Ⅲ再到Winsor Ⅱ的相转变过程，中相乳液体积较大，乳液稳定性好。NaCl加量为8% 时，配比为1∶1和2∶3的复配表面活性剂乳液的平均粒径均达到最小值，分别为7.52、10.01 μm。此外，该配比下 的复配表面活性剂溶液还具有良好的增溶效果，油增溶量分别高达68、64 mL/g。具有低界面张力和高润湿角的 PNC/DP6E6S复配体系有利于低渗透储层的降压增注。与水驱相比，配比为1∶1和2∶3的表面活性剂体系的降 压率分别可达到28.9%和23.9%，采收率提高21.85百分点和18.92百分点。PNC、DP6E6S配比为1∶1的复配表面 活性剂体系降低毛细管力的能力强于配比为2∶3的体系，降压增注效果更好。

Low permeability reservoirs have the characteristics of small pore throat radius，low permeability and poor water absorption，resulting in unsatisfactory chemical flooding effect. Aiming at this problem，propylene oxide and ethylene oxide were introduced into dodecyl alcohol and sulfonated to obtain alcohol ether sulfonate（DP6E6S）. Then，a compound system of DP6E6S and C16-carboxybetaine（PNC）surfactant was constructed. The surface/interface，aging，adsorption，wettability and emulsification properties of the system were evaluated. Finally，the injection enhancement performance of compound system was explored by core flow experiment. The results showed that PNC and DP6E6S exhibited strong synergistic effect. Compared with a single surfactant，the compound system effectively reduced the critical micellar concentration and surface tension，while enhanced the stability and adsorption resistance of emulsion. The PNC/DP6E6S surfactant system with a molar ratio of 1∶1 and 2∶3 demonstrated strong anti-aging properties. It could maintain the oil-water interfacial tension to 10-3 mN/m in a wide range of salinity（5%—10%）. After aging at 60 ℃ for 30 days，the oil-water interfacial tension had no obvious change. With the increase of salinity，the emulsion prepared by the compound surfactant would undergo phase transition from Winsor I to Winsor Ⅲ and then to Winsor Ⅱ. The medium phase emulsion exhibited a larger volume and better stability. The average particle sizes of the compound surfactant emulsion with ratios of 1∶1 and 2∶3 reached the minimum value（7.52 and 10.01 μm）at NaCl concentration of 8%. In addition，the compound surfactant solution at these ratios also demonstrated excellent solubilization effect，with oil solubilization up to 68 and 64 mL/g，respectively. The PNC/DP6E6S compound system，with low interfacial tension and high wettability angle，was beneficial for reducing pressure and increasing injection in low permeability reservoir. Compared with water flooding，the depressurization rate of 1∶1 and 2∶3 surfactants could reach 28.9% and 23.9%，respectively，meanwhile the recovery efficiency could be increased by 21.85 percentage points and 18.92 percentage points. The ability of the compound surfactant system with a 1∶1 ratio of PNC to DP6E6S in reducing capillary forces was superior to that with a 2∶3 ratio，resulting in better pressure drop reduction and enhanced oil recovery.

10.19346/j.cnki.1000-4092.2023.03.015