摘要
介绍了低渗透水驱油藏电化学导流驱油这种提高油井产量和采收率的新方法 ,简介了驱油机理 :电渗效应 ,电泳效应 ,外加电场改变储层孔隙结构和粘土矿物性质 ,电解及电解产物的作用 ,岩石润湿性改变。详细介绍了在外加电场作用下岩心水驱油实验程序。在低渗透的油藏岩心和人造岩心上外加电场 ,用不同矿化度和离子组成的水驱替模拟油 (饱和和驱替岩心使用同一种水 ) ,得到了以下实验结果。驱替水矿化度和二价离子含量影响驱油效果 ,在电场强度一定时 ,随水矿化度增加 ,油采收率和油相相对渗透率的升高幅度及产水率和水相相对渗透率的降低幅度呈现先增大后减小的规律 ,在一个最佳矿化度范围内驱油效果最佳 ,这一最佳矿化度范围对于两组实验岩心 (孔隙度 16 .6 %— 17.0 %和N2 气测渗透率 9.9× 10 -3 — 10 .4× 10 -3 μm2 ;孔隙度 14.8%— 14.9%和N2 气测渗透率 9.9× 10 -3 — 10 .8× 10 -3 μm2 )分别为 5 0 0 0 0— 70 0 0 0mg/L和 30 0 0 0— 5 0 0 0 0mg/L ;驱替水中钙镁离子含量增加导致驱油效率降低。对实验结果作了分析、讨论。
Electrochemical guiding flow (ECGF) as a novel method for increasing well productivity and improving oil recovery of water flooding low permeability reservoirs is presented. The mechanisms involved in ECGF are introduced briefly: electroosmosis, electrophoresis, changes in pore structure and clay mineral nature under an electric field (EF) applied; electrolysis and functioning of electrolysates, and rock wetability alteration. The experimental procedure of water flooding oily cores under applied electric field is described in some detail. In the experiments conducted on reservoir and artificial cores under EF, brines of different salinity and Ca 2+ +Mg 2+ content are used to displace a model oil and following results are obtained. The salinity and Ca 2+ +Mg 2+ content of the flooding brine exert notable influence on oil displacement; under EF of given strength the increment of oil recovery and relative permeability for oil phase as well as the decrement of water cut and relative permeability for water phase, as a rule, enlarge at the first step and then drop down with the brine salinity rising and there exists an optimum salinity range in which oil recovery efficiency is the highest. The optimum salinity is ranged 50 000-70 000 mg/L for one set of experimental cores (porosity 16.6-17.0% and N 2 permeability 9.9×10 -3 -10.4×10 -3 μm 2) and 30 000-50 000 mg/L for another (porosity 14.8-14.9% and N 2 permeability 9.9×10 -3 -10.8×10 -3 μm 2); increasing Ca 2+ +Mg 2+ in the brine leads to decreasing its displacing efficiency for oil. The experimental results obtained are analyzed and discussed.
出处
《油田化学》
CAS
CSCD
北大核心
2001年第4期320-325,共6页
Oilfield Chemistry
基金
国家自然科学基金资助项目"外加电场作用下孔隙渗流机理与理论研究"(批准号 5 98740 2 0 )
关键词
电化学导流
低渗透油藏
水驱
增产措施
电化学方法
储层
地层水矿化度
驱油机理
Electrochemical Guiding Flow
Low Permeability Reservoirs
Water Flooding
Reservoir Stimulation
Electrochemical Method
Formation Water Salinity
Oil Displacement Mechanisms
