二元复合体系动用不同模态孔隙结构的剩余油

Effect of modes of pore structure on pore-scale residual oil displacement in polymer/surfactant flooding

刘哲宇 魏秋帆 张菁 张德福 吕建荣 李宜强 2

中国石油大学（北京）油气资源与探测国家重点实验室，北京 102249 中国石油大学（北京）石油工程学院，北京 102249 中国石油新疆油田分公司勘探开发研究院，新疆　克拉玛依 834000

State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China Research Institute of Exploration and Development, Xinjiang Oilfield Company, PetroChina, Karamay 834000, China

按照已有的分类结果选取３种孔隙结构的天然岩心，利用核磁共振原位驱替实验，通过信号幅度的变化研究水驱、二元复合驱过程中各种孔隙结构岩心中的剩余油变化规律，并利用核磁成像观测孔隙中的剩余油位置，明确从各个孔隙采出的油量对总采收率的贡献程度。结果表明：从单模态到复模态孔隙结构岩心的孔隙发育情况和孔喉连通性逐渐变差，水驱油效果变差，二元复合驱提高采收率幅度升高；对于单模态岩心，二元复合驱阶段从中小孔隙中采出的油量对总采收率的贡献较水驱阶段增加，1~3　μm的孔隙得到了有效动用；对于双模态和复模态孔隙结构岩心，二元复合驱阶段仍以动用大中孔隙为主。

According to the existing classification result, three natural cores with similar permeability but different pore structures were selected for nuclear magnetic resonance(NMR) in-situ flooding experiments. The distribution and migration patterns of residual oil in different flooding processes were evaluated by quantitatively analyzing the change of the signal amplitude. Meanwhile, the nuclear magnetic imaging was used to investigate the distribution of residual oil in pores and thus the contribution of recovered oil from different pore structures to overall oil recovery were evaluated. Results show that: from the single modal core to the complex modal core, the porosity evolution and pore-throat connectivity were gradually deteriorated, and the water flooding efficiency got worse, while the SP flooding efficiency increased. For the single modal core, compared to the water flooding, residual oil in small and medium pores of 1￣3 μm could be mobilized during SP flooding. But for bimodal core and complex modal core, the oil is mainly extracted from the large and medium pores.

10.6056/dkyqt201903014