两性离子表面活性剂和纳米颗粒为起泡剂的高稳定性超临界二氧化碳泡沫封窜体系

Highly Stable Supercritical CO₂ Foam with Zwitterionic Surfactant and Nanoparticle as Foaming Agents for Channeling Blocking

李伟涛 李宗阳 张 东 张传宝 李友全

LI Weitao LI Zongyang ZHANG Dong ZHANG Chuanbao LI Youquan

胜利油田低渗透油藏具有埋藏深（＞3000m）、温度高（＞120℃）、非均质性强等特点，针对低渗透油藏CO2 驱波及效率低、常规泡沫高温调驱性能变差等问题，构建了由两性离子表面活性剂（HSD）和改性SiO2 纳米颗粒 为起泡剂的高稳定性超临界CO2 泡沫体系。研究了该体系在高温下的起泡性能和耐温性能；分别评价了纳米 SiO2 对超临界CO2 泡沫体系流变特性、封堵特性以及调驱性能的影响；最后探讨了纳米颗粒强化超临界CO2 泡沫 的稳定机理。结果表明，高稳定性超临界CO2 泡沫体系表现出良好的起泡性能和耐高温特性，随着体系中纳米颗粒浓度的增加，泡沫半衰期先增加后降低。在110℃下，0.5%的纳米颗粒可使泡沫析液半衰期由17min提高到40min，稳定性提高了近1.5倍。在相同的剪切速率下，体系的表观黏度随纳米颗粒浓度的增加而增加，稠度系数由0.073增至1.220。在岩心封堵实验中，泡沫在多孔介质中的稳态表观黏度随纳米颗粒浓度的增加而增 加，封堵强度逐渐增强；超临界CO2 泡沫呈“颗粒状”堆叠排放，泡沫直径为10～20μm。超临界CO2 泡沫具有较 好的调驱性能，能封堵高渗透通道，迫使后续注入的CO2 进入低渗透基质中，从而提高采收率。表面活性剂分子吸附在纳米SiO2 表面使其具有了界面活性，进而纳米SiO2 吸附到气液界面上，提高了泡沫稳定性。

Low permeability reservoirs in Shengli oilfield are characterized with deep burial depth（＞3000 m），high temperature （>120 ℃），and strong heterogeneity. Aiming at the problems of low sweep efficiency of CO2 flooding and poor profile control performance of conventional foam，a highly stable supercritical CO2 foam system with zwitterionic surfactant（HSD）and modified SiO2 nanoparticles as foaming agents was developed. The foaming performance and temperature resistance of the system at high temperature were studied. The effects of nano-SiO2 on the rheological properties，plugging properties and profile control performance of supercritical CO2 foam system were evaluated respectively. Finally，the stabilization mechanism of nanoparticle reinforced supercritical CO2 foam was discussed. The results showed that the highly stable supercritical CO2 foam system had good foaming performance and temperature resistance. With increasing dosage of nanoparticle in the system，the half-life of foam gradually increased first and then decreased. At 110 ℃，0.5% nanoparticle could increase the half-life of foam drainage from 17 min to 40 min，and then the stability was improved by nearly 2.5 times. At the same shearing rate，the apparent viscosity of the system increased with the increase of nanoparticle concentration，and then the consistency coefficient increased from 0.073 to 1.220. In the core flooding experiment，the steady-state apparent viscosity of foam in porous media increased with the increase of nanoparticle concentration，thereby increasing the plugging strength. Supercritical CO2 foam was stacked and discharged in“granular”shape. The foam size was 10—20 μm. Supercritical CO2 foam had good profile control and displacement performance，which could block high permeability channels and compel subsequent injected CO2 into low permeability matrix，thus improving oil recovery. Surfactant molecules adsorbed on the surface of nano-SiO2 ，which made it have interfacial activity，and then nano-SiO2 adsorbed on the gas-liquid interface to improve the stability of foam.

10.19346/j.cnki.1000-4092.2024.01.014