Study on the Efficiency of Different Polymers Used in Polymer Injection (Flooding) Operations in Enhanced Oil Recovery of Heavy Oil Reservoirs

Only 10% of Iran's oil reservoirs have a sandy structure and the rest have a carbonate structure. Therefore, a relatively large part of the oil in these reservoirs is heavy and can not be extracted by conventional methods. For this reason, methods called enhanced recovery are used to increase the recovery factor of oil reservoirs. Enhanced recovery is performed by secondary and tertiary methods, which include thermal and chemical methods and gas injection are among the tertiary methods. One of the chemical methods is polymer flooding. For many years, polymers have been used to control the mobility of injected water and to enhanced recovery of oil reservoirs. By increasing the viscosity of polymers, they reduce the mobility of water, increase the stability of the kinematic profile, reduce the phenomenon of finger injection of the injected fluid, and finally increase the oil production from the reservoir. In this paper, first the application of polymers in oil reservoirs, then the types of polymers used in the discussion of enhanced oil recovery, including polyacrylamides, alkali-surfactant-polymer, xanthanes, polysaccharides, and hydroxyethyl cellulose have been investigated. In addition, destructive factors of polymer structure, factors affecting polymer flooding, different injection patterns, screening criteria, and in general parameters affecting the succesful operation and its general dimensions, as well as, simulation of polymer flooding in one of the Iranian oil fields are investigated.