摘要
纳米乳液作为一种纳米级胶体分散体系,因其优异的界面性能以及提高采收率效果被广泛应用于非常规油藏开发。基于低能乳化法制备了水包油型纳米乳液体系,通过室内实验明确纳米乳液静态吸附性能、润湿反转性能以及自发渗吸的内在联系,并分析纳米乳液在致密砂岩油藏中的渗吸增产作用机理。实验结果表明:纳米乳液的平均粒径小于10nm,满足进入致密砂岩绝大部分孔喉的粒径要求,在致密孔喉内能充分扩散运移,从而扩大渗吸作用范围。纳米乳液的临界胶束质量分数为0.015%,能够有效降低油水界面张力至2 mN/m左右。纳米乳液的吸附等温线符合Langmuir吸附模型,其润湿反转机理以吸附机理为主。纳米乳液能够增溶原油,并通过乳化作用进一步分散原油,减小乳状液中油滴尺寸,减弱油滴通过孔喉时的贾敏效应,降低渗流阻力。岩心润湿性会影响渗吸采收率,随着岩心亲水性增强而增加,不同润湿性岩心自发渗吸时孔隙动用程度存在差异,加入纳米乳液能显著提高油湿岩心内小孔渗吸采收率。同时,增加纳米乳液浓度与边界开放程度可以提高渗吸采收率,这主要是由于致密砂岩自发渗吸受毛细管力主导,边界开放程度增加能够扩大纳米乳液接触面积,纳米乳液浓度增加能够增强润湿反转作用与乳化作用,从而增强自发渗吸效果。
Nanoemulsion,as a kind of nanoscale colloidal dispersion system,has been widely applied in unconventional oil reser-voir development due to its outstanding interfacial properties and enhanced oil recovery effects.Water-in-oil type nanoemulsion sys-tems are prepared based on the low-energy emulsification method.The intrinsic relationships among the static adsorption,wettabil-ity alteration,and spontaneous imbibition of nanoemulsion are determined by laboratory experiments,elucidating the mechanism of imbibition and production enhancement of nanoemulsion in tight sandstone oil reservoirs.The laboratory results show that the av-erage droplet size of nanoemulsion is less than 10 nm,which can meet the droplet size requirement of entering most of the pore throat of tight sandstone and can fully diffuse and migrate in the tight pore throat,thus expanding the imbibition range.The critical micelle mass fraction of the nanoemulsion is 0.015%,which can effectively reduce the oil-water interfacial tension to about 2 mN/m.The adsorption isotherm of the nanoemulsion conforms to the Langmuir adsorption model,and the wettability alteration mecha-nism is mainly adsorption.The nanoemulsion can dissolve the crude oil,further disperse the crude oil through emulsification,re-duce the size of oil droplets in the emulsion,and weaken the Jamin effect when oil droplets pass through the pore throat,reducing seepage resistance.Core wettability will affect the spontaneous imbibition recovery,and the imbibition recovery will increase with the increase in core hydrophilicity.There are differences in the oil recovery at the pore scale in different wettability core spontaneous imbibition,and the addition of nanoemulsion can significantly improve the recovery of small pores in the oil-wet core.Meanwhile,increasing nanoemulsion concentration and boundary openness can improve the spontaneous imbibition recovery efficiency.This is mainly because tight sandstone imbibition is dominated by capillary force,increasing boundary openness can expand the contact area of nanoemulsion,and increasing nanoemulsion concentration can improve the wettability alteration and emulsification,thus improving the effect of spontaneous imbibition.
作者
袁帅
周福建
李源
梁星原
梁天博
姚二冬
YUAN Shuai;ZHOU Fujian;LI Yuan;LIANG Xingyuan;LIANG Tianbo;YAO Erdong(National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing City,102249,China;Key Laboratory of Petroleum Engineering Education Ministry,China University of Petroleum(Beijing),Beijing City,102249,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing City,100083,China)
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2024年第1期126-136,共11页
Petroleum Geology and Recovery Efficiency
基金
国家自然科学基金面上项目“分离压微尺度效应作用下的压裂液渗吸提高采收率机理”(52274051)
国家自然科学基金青年基金项目“致密油储层压裂后渗吸动用程度微观控制机理研究”(52204059)。
关键词
致密砂岩
纳米乳液
润湿反转
静态吸附
自发渗吸
tight sandstone
nanoemulsion
wettability alteration
static adsorption
spontaneous imbibition
