大庆油区强碱三元复合驱后储层孔喉结构变化  

Reservoir pore-throat structure changes after strong base ASP flooding in Daqing oilfield

作　　者：何金钢[1,2] 宋考平[1] 康少东 杨晶[1] 董秀龙 

机构地区：[1]东北石油大学提高油气采收率教育部重点实验室,黑龙江大庆163318 [2]中国石油大庆油田有限责任公司,黑龙江大庆163000 [3]中国石油大庆油田有限责任公司采油一厂,黑龙江大庆163000

出　　处：《油气地质与采收率》2015年第4期97-102,108,共7页Petroleum Geology and Recovery Efficiency

基　　金：国家自然科学基金重点项目"低渗透油层提高驱油效率的机理研究"(50634020);国家油气重大专项"复杂油气田地质与提高采收率技术"(2009ZX05009-004-01);东北石油大学研究生创新科研项目"基于多尺度描述的三元复合驱后剩余油分布及储层物性变化规律研究"(YJSCX2014-019NEPU)

摘　　要：为了了解强碱三元复合驱后储层孔喉结构变化规律,利用常规压汞、恒速压汞、扫描电镜和铸体薄片分析方法,对大庆油区强碱三元复合驱前、后岩样孔喉结构变化进行定性和定量研究。结果表明:强碱三元复合驱后颗粒边界经过强碱溶蚀呈锯齿状,颗粒去棱角化明显,长石溶蚀严重,同时能够观察到大量溶蚀孔隙,粘土矿物中大量的书架状高岭石被溶蚀,且在粘土矿物表面出现次生石英。白色云雾状垢沉淀充填在孔隙中造成孔喉结构发生变化,部分孔隙阻塞,使强碱三元复合驱后岩心喉道半径平均值均较水驱岩心下降6.528%,孔隙半径平均值下降3.360%,孔喉比分布范围更大,平均增加12.839%,最终含油饱和度较水驱岩心低,最终含油饱和度系数较小,且强碱损害前、后残余油饱和度和最终含油饱和度的变化率均随着岩心渗透率的增加而减小。强碱三元复合驱后渗透率级差由水驱的5.567增加到5.691,岩心非均质性增强使发生指进和窜流的可能性增大。强碱三元复合驱后的储层孔喉结构变差将极大地影响后续水驱和进一步提高采收率方法的实施,也使得薄差层的动用难度进一步增加。Pore-throat structure before and after strong base ASP flooding in Daqing oilfield was researched qualitatively and quantitatively using mercury injection,rate-controlled mercury injection,SEM and casting thin sections analysis. The results show that grain boundaries are dissolved and zigzag-like with unclear edges and corners,and feldspar is dissolved seriously by alkali after base ASP flooding. A large number of dissolution pores were observed. Kaolinite is dissolved and secondary quartz formed on clay mineral surface at the same time. White cloud-like scale deposits filling in pores result in changes in pore structure and partial pores are plugged. Average core throat radius dropped by 6.528% and average pore radius dropped by 3.360%. Pore-throat ratio had wider distribution and increased by 12.839% averagely. The final oil saturation was lower than that of water drive core and its final oil saturation coefficient was smaller. The residual oil saturation and ultimate oil saturation decreased with the increase of core permeability before and after strong base damage. Permeability ratio changed from 5.567 to 5.691 after the strong base ASP flooding. The stronger core heterogeneity brings more possibility of fingering and channeling. The poor pore throat structure will greatly influence the subsequent water flooding and the implementation of enhancing oil recovery method,and also bring about difficulties in thin and poor layers.

关 键 词：强碱三元复合驱 孔喉结构 恒速压汞 扫描电镜 铸体薄片 

分 类 号：TE357[石油与天然气工程—油气田开发工程]