聚合物驱不可入孔隙体积效应的室内研究及应用评价

基于聚合物互溶驱替和弥散渗流原理,利用双段塞浓度剖面法测定了聚合物溶液在长庆油田侏罗系延10储层6块岩心上的不可入孔隙体积(IPV),考察其对聚驱效果的影响。结果表明,聚合物溶液在6块岩心上的IPV值为20.6%~27.9%,平均为24.8%。岩心渗透率越高,IPV值越小,二者呈明显的线性负相关关系。IPV值与孔隙度无明显对应关系。不可入孔隙体积的大小反映聚合物分子线团与储层孔喉大小的匹配程度。M区块延10油藏聚合物驱试验结果表明,考虑聚合物驱过程中不可入孔隙体积效应的存在,在矿场注入工艺设计时适当提高注入量和增加前置保护段塞,有利于提升驱油效果。聚合物驱方案设计时考虑不可入孔隙体积效应是必要的。

Experimental study and application evaluation of inaccessible pore volume for polymer flooding

Based on the principle of polymer miscible displacement and diffusion percolation,the inaccessible pore volume (IPV) is determined by using double polymer flooding slug profile method from 6 drilling cores in Changqing Jurassic Yan-10 reservoir,and its influence on polymer flooding effect is thereby investigated.Studied results indicate that the value of IPV for 6 drilling cores ranges from 20.6％ to 27.9％ with average value of 24.8％.It reveals that the bigger the permeability of the drilling cores is,the smaller the IPV value is.The two parameters between the value of IPV and drilling core permeability show a significant negative linear correlation without significant relationship between the value of IPV and drilling core porosity.Inaccessible pore volume reflects the matching degree between the size of polymer molecular mass and reservoir pore throat size.Polymer flooding test of Yan-10 reservoir in M Block shows that the existence of inaccessible pore volume effect in the process of polymer flooding is conducive to enhance oil displacement efficiency by increasing the injection volume or increasing the protection slug properly in field injection process design.Therefore,it is necessary to consider the inaccessible pore volume effect in the development of polymer flooding scheme.