Selection of polymer flooding agent for tertiary oil recovery in oilfields

Oilfield Chemicals, thermal medium or fluid that can be mixed with crude oil into the oil reservoir, changing the physical property of crude oil in the oil reservoir and increasing the oil reservoir pressure, so as to improve the ultimate oil recovery of the oil field, this mining method is called tertiary oil recovery, also known as enhanced oil recovery. The main technologies of tertiary oil recovery include thermal oil recovery, gas miscible flooding, chemical flooding and other oil recovery technologies. Other oil recovery technologies include microbial flooding, ultrasonic flooding, electromagnetic flooding and so on. The tertiary oil recovery methods such as polymer flooding and ternary compound flooding are another effective method to enhance oil recovery after water flooding.

 

Tertiary oil recovery

Polymer flooding is an oil flooding method that injects a water-soluble polymer solution with a certain relative molecular weight into the reservoir to change the ratio of oil water flow and expand the swept volume. Successful polymer flooding schemes generally increase recovery by 7% to 15%. In oilfield polymer flooding engineering, there are two kinds of commonly used polymers: one is synthetic polymer, mainly by acrylamide monomer polymerization of polyacrylamide, commonly used is partially hydrolyzed polyacrylamide; The other is a natural polymer, and the most used is yellow wrap.

 

Polyacrylamide

However, the polymer commonly used in the actual production of tertiary oil recovery is polyacrylamide, because in the polymer, although the natural polymer yellow adhesive has better shear resistance and acid resistance, the price of yellow adhesive is relatively expensive. Therefore, polyacrylamide is generally used except in harsh oil formations. Polyacrylamide is known as polyacrylamide and is abbreviated as PAM. Partially hydrolyzed polyacrylamide is commonly used in oil displacement, where the English word for hydrolysis is Hydrolization, so the partially hydrolyzed polyacrylamide is abbreviated as HPAM.

The main mechanism that polyacrylamide can improve oil recovery is to increase the water-phase viscosity, improve the water-oil mobility ratio, and expand the swept volume. At the same time, due to the viscoelasticity of polyacrylamide solution, the oil displacement efficiency can also be improved.