江汉油田高盐油藏低界面张力泡沫驱提高采收率研究

Enhanced Oil Recovery Technique of Foam Flooding with Low Interfacial Tension for High Salinity Reservoir in Jianghan Oilfield

为提高江汉油田高盐中低渗油藏注水开发后期的原油采收率,用起泡剂和稳泡剂配制了泡沫体系,通过考察起泡剂类型、浓度及稳泡剂浓度对泡沫体系发泡体积和半衰期的影响优选了泡沫体系配方,研究了泡沫体系的耐油性、耐盐性及耐老化性,对泡沫驱注入参数进行了优化,通过对并联岩心的驱油实验考察了泡沫体系的封堵能力。研究结果表明,起泡剂和稳泡剂质量分数均为0.4%时,泡沫体系的发泡能力良好,发泡体积为110 mL,半衰期为427 min,泡沫体系与原油的界面张力较低(10^(-2)mN/m数量级);泡沫体系耐油性较好,在含油量为30%时的半衰期为40 min;耐盐性良好,在矿化度为300 g/L或钙镁离子为5 g/L时的半衰期大于350 min;耐老化性良好,在70℃下老化100 d的发泡体积和半衰期变化较小;低界面起泡剂氮气驱最佳注入参数为:气液比1.5∶1、注入段塞0.4 PV、注入速度1.2 mL/min,在此条件下泡沫体系可提高单管岩心采收率7.51%、并联岩心采收率10.04%,对王场油田高盐非均质油层具有良好的调驱效果。

In order to enhance the oil recovery of medium porosity reservoir in post water flooding of Jianghan oilfield with high salinity, a foam system composed of foam agent and foam stabilizer was developed. The formula of foam system was optimized, by investigating the effect of foam agent type, concentration and the foam stabilizer concentration on foam volume and half-life. The oil resistance, salt tolerance and aging resistance of foam system were evaluated and the injection parameters for foam flooding were optimized. The sealing ability of foam system was investigated through the parallel core displacement experiment. The experiment results showed that the foaming ability of foam system composed of 0.4% foam agent and 0.4% foam stabilizer was good with 110 mL foam volume and 427 rain half-life. The interfacial tension between foam system and crude oil was lower （10-2 mN/m）. Foam system had good oil resistance. The half-life was 40 min when the oil content of foam system was 30%. The half-life of foam system was greater than 350 min when the salinity was 300 g/L or the concentration of calcium and magnesium ions was 5 g/L, indicating good salt tolerance. The foam volume and half-life changed a little after the foam system aging at 70℃ for 100 days, showing good aging resistance. The optimum injection parameter of nitrogen foam flooding with low interracial tension was obtained as follows： 1.5：1 gas-liquid ratio, 0.4 PV injection volume, 1.2 mL/min injection rate. The oil recovery ratio increased 7.51% in single core and 10.04% in dual cores by foam system under optimum conditions. There were better profile modification in Wangchang oilfield with high salinity and heterogeneous oil reservoir.