双河油田IV5-11层系复合驱油体系实验研究

Laboratory research of oil displacement compound system for layer IV5-11,Shiianghe oilfield

根据双河油田IV5-11层系的油藏特征,利用正交实验法,对聚合物质量浓度、表面活性剂种类及其质量分数进行筛选,得到了由质量浓度为1500mg/L的ZL-Ⅱ、质量分数为0.3%的QY-3组成的二元复合驱油体系及由质量浓度为1500mg/L的ZL-Ⅱ、质量分数为0.3%的QY-3和1.0%的Na2CO3组成的三元复合驱油体系,这2个体系均能与双河模拟油形成超低界面张力且粘度适中。利用均质与非均质人造岩心及微观非均质仿真模型,对所选复合驱油体系进行物理模拟驱油实验;并在模拟油藏具有代表性的3倍渗透率级差条件下,优选了三元复合驱油体系注入方式。实验结果表明,在均质条件下,三元复合驱油体系提高采收率程度明显高于二元复合驱油体系;在非均质条件下,随着非均质性的增强,三元复合驱油体系与二元复合驱油体系提高采收率的差距逐渐缩小,但前者始终高于后者;对于同一驱油体系,随着非均质性的增强,驱油效率先增大后减小,渗透率级差为3倍时的采收率最高。综合分析可知,三元复合驱油体系好于二元复合驱油体系,在其注入前后分别注入0.05倍孔隙体积交联聚合物保护段塞的注入方式,三元复合驱油体系提高采收率比不加保护段塞时提高了4%。

Based on the reservoir properties of layer Ⅳ5-11 in Shuanghe oilfield,the polymer mass concentration,surfactant types and mass fraction are selected through orthogonal test method.The binary system and ASP system are obtained.And,the binary system is composed of ZLⅡ whose mass concentration is 1500 mg/L and QY-3 whose mass fraction is 0.3%.The ASP system is composed of ZL-Ⅱ whose mass concentration is 1500 mg/L,QY-3 and Na2CO3 whose mass fraction is respectively 0.3% and 0.1%.These two systems all can form ultra-low interfacial tensions for the Shuanghe oil,and all can achieve moderate viscosity.Using homogeneous and nonhomogeneous artificial core and microscopic heterogeneity simulation model,the displacement experiments of selected compound flooding systems are conducted.And,when the reservoir permeability difference is 3 which is representative conditions,the ASP system injection mode may be optimized.The results show that the EOR effect of ASP system is obviously better than that of binary system in homogeneous conditions.And,in heterogeneity conditions,as the heterogeneity increased,the EOR effects difference between ASP system and binary system decreased.But,the EOR effect of ASP system is still better than that of binary system.For the same oil displacement system,as the heterogeneity increased,the oil recovery will increase firstly and then decrease,and the EOR performance reaches peak when the permeability difference is 3.Through comprehensive analyses,the ASP system is better than binary system.And,when injected 0.05 PV cross-link polymer slug both before and after ASP,the oil recovery after ASP flooding will be increase by 4% compared to corresponding un-plug.