羧基纳米纤维素乳液性能测试及驱油效率研究  

Experimental Study on Performance and Oil Displacement Efficiency of CCNF Emulsions

作　　者：袁杰[1] 刘德新[1] 何娟 贾寒[1] Yuan Jie;Liu Dexin;He Juan;Jia Han(School of Petroleum Engineering,China University of Petroleum(East China))

机构地区：[1]中国石油大学(华东)石油工程学院

出　　处：《石油机械》2023年第1期78-85,146,共9页China Petroleum Machinery

基　　金：国家自然科学基金重点项目“高效耐盐两亲聚合物超分子包合驱油体系增效方法及作用机理”(52130401);国家自然科学基金项目“特低渗油藏壁面流体层调控机理与方法”(51974344)。

摘　　要：为了开发稳定、绿色、高效的乳液驱油体系,选取3种不同长径比羧基纳米纤维素(CCNF-1、CCNF-2和CCNF-3)作为乳化剂,进行乳液驱油试验研究。通过透射电子显微镜观察了不同长径比羧基纳米纤维素的形貌,采用光学显微镜和乳液稳定性分析测试仪考察了不同长径比羧基纳米纤维素乳液的稳定性,应用旋转流变仪评价了不同长径比羧基纤维素水分散液和乳液的流变行为,最后通过岩心驱替试验评价了羧基纳米纤维素乳液的驱油潜力。研究结果表明:3种不同长径比的羧基纳米纤维素均能与正辛烷形成稳定的Pickering乳液;在质量分数为0.4%时,CCNF-2具有最好的乳化性能;同时CCNF-2稳定的乳液稳定性也最好,在180 min内,乳液稳定性指数(TSI)仅增长了0.50。稳态流变测试还表明,CCNF-2水分散液及其稳定的乳液黏度最大。由于CCNF-2具有最大的长径比,其分子之间相互纠结缠绕导致其黏度增大。此外,CCNF-2的羧基与排列或交联的CCNF-2之间有更多的氢键可以增强在油水界面吸附层的三维网络结构的强度。岩心驱替结果表明,CCNF-2乳液具有更好的驱油潜力,乳液注入阶段采收率提高14.7%。因此CCNF-2乳液可作为绿色驱油剂用来提高采收率。研究结果对油田现场化学驱油提高采收率具有一定的指导意义。Three types of carboxylated cellulose nanofibers(CCNFs) with varied length-to-diameter(L/D) ratios(CCNF-1,CCNF-2 and CCNF-3) were selected as emulsifiers to develop stable, green and high-efficiency emulsion oil-displacing systems, and the emulsion-based oil displacement tests were performed.The morphologies of CCNFs with varied L/D ratios were observed via transmission electron microscopy, and the corresponding emulsion stability was investigated via optical microscopy and the emulsion stability test device.Also.The rheology of the aqueous dispersion and emulsion of the CCNFs were evaluated via the rotary rheometer.Finally, the oil displacing potential of the CCNFs is assessed via the core flooding test.The results show that all three CCNFs can form stable Pickering emulsions with normal octane.CCNF-2 presents the optimal emulsion performance with the mass fraction of 0.4%,and it also delivers the highest emulsion stability during tests-with the turbiscan stability index(TSI) increased by only 0.50 within 180 min.The steady rheological test indicates that the aqueous dispersion and emulsion of CCNF-2 have the highest viscosity.The higher viscosity of CCNF-2 is because the CCNF-2 is associated with the highest L/D ratio, and the molecules intertwine with each other.In addition, among carboxyl groups of the CCNF-2 and the arranged or cross-linked CCNF-2 exist more hydrogen bonds, which strengthen the three-dimensional network structure of the adsorption layer at the oil-water interface.The core flooding test demonstrates that CCNF-2 has higher oil displacing potential, and the recovery factor is increased by 14.7% during the emulsion injection.To sum up, CCNF-2 carboxyl nanocellulose emulsion is a green oil-displacing agent for enhanced oil recovery.

关 键 词：化学驱油 羧基纳米纤维素 Pickering乳液 长径比 稳定性 

分 类 号：TE357[石油与天然气工程—油气田开发工程]