埕北油田弱碱三元复合驱可行性实验研究

Experimental study on feasibility of the weak base ASP flooding in Chengbei Oilfield

埕北油田具有原油黏度高、油层渗透能力强和非均质性严重等特点，水驱开发效果差，剩余油储量大，而生产平台工作时间已达到设计使用寿命，急需高效、快速的提高采收率技术。针对埕北油藏地质、流体性质和开发现状，利用仪器检测和理论分析方法，开展了聚合物溶液、三元复合体系和改性三元复合体系性质和调驱效果实验研究。结果表明，与三元复合体系相比较，添加入Cr^3＋后得到的改性三元复合体系在黏度和界面张力性质方面几乎没有发生变化，但其阻力系数和残余阻力系数有了较大幅度提高。在化学费用相近条件下，“调剖＋三元复合驱”和改性三元复合驱要比三元复合驱增油效果好，采收率增幅可以达到15％以上。推荐埕北油田采用弱碱三元复合驱，三元复合体系配方组成为“大庆超高”聚合物（CP=1600～1800mg／L）＋弱碱Na2CO3（CA=0．6％～1．0％）＋重烷基苯石油磺酸盐（Cs=0．10％～0．15％）＋有机铬（聚：Cr^3＋=120：1～240：1）”，段塞组合方式为“0．025～0．05 PV Cr^3＋聚合物凝胶＋0．12～0．15PV三元复合体系”。

Characteristics of Chengbei Oilfield is high oil viscosity, high permeability, and serious heterogeneity which resulted in bad water flooding effect and a large reserve volume of remaining oil. At present, the working time of producing platform has met its design lifetime, so it is necessary to develop high efficient technique to enhance oil recovery. Aiming at the reservoir geologic characteristics, fluid property and present developing situation, making use of the instrument detection and theoretical analysis, property of the polymer solution, ASP multisystem, modified ASP multisystem and its effect on profile control and oil displacement was studied. The results showed that the addition of Cr^3＋ has little influence on the viscosity and interracial tension of ASP multisystem, but there is an apparent increase in resistance factor and residual resistance factor. Under the condition of the similar cost, the ＂adjusting entry profile ＋ ASP multisystem＂ and modified ASP multisystem have better effect on enhancing oil recovery than the conventional ASP multisystem, and recovery ratio is increased by more than 15%. Therefore, the weak base ASP multisystem is recommended to adopt in Chengbei Oilfield, its composition is as follows： ＂the polymer （Daqing Chaogao） （Cp = 1 600-- 1 800 mg/L） ＋ weak base Na2CO3（CA = 0.6% -- 1.0% ） ＋ heavy alkyl benzene mahogany sulfonate （Cs = 0.10 % -- 0.15 % ） ＋ chromium （polymer： Cr^3＋ = 120 ： 1 240： 1）＂, and its slug array mode is ＂0. 025 --0.05 PV Cr3＋ polymer gel ＋ 0.12--0.15 PV ASP multisystem ＂