Experimental investigation of microscopic/macroscopic efficiency of polymer flooding in fractured heavy oil five-spot systems

This paper concerns on experimental investigation of biopolymer/polymer flooding in fractured five-spot systems. In this study, a series of polymer injection processes were performed on five-spot glass type micromodels saturated with heavy crude oil. Seven fractured glass type micromodels were used to illustrate the effects of polymer type/concentration on oil recovery efficiency in presence of fractures with different geometrical properties (i.e., fractures orientation, length and number of fractures). Four synthetic polymers as well as a biopolymer at different levels of concentration were tested. Also a micromodel constituted from dead-end pores with various geometrical properties was designed to investigate microscopic displacement mechanisms during polymer/water flooding. The results showed that polymer flooding is more efficient by using hydrolyzed synthetic polymers with high molecular weight as well as locating injection well in a proper position respect to the fracture geometrical properties. In addition, by monitoring of microscopic efficiency, pulling, stripping, and oil thread flow mechanisms were detected and discussed. The results showed that flow rate, fluid type, polymer concentration, and geometrical properties of pores influence the efficiency of mentioned mechanisms. Furthermore, it was detected that polymer's velocity profile play a significant role on oil recovery efficiency by influencing both macroscopic and microscopic mechanisms. This study demonstrates different physical and chemical conditions that affect the efficiency of this enhanced oil recovery method