In the oilfield industry, polymers are widely used in many areas:

1. Drilling mud: Polymers have multiple functions: viscosity modifiers, fluid loss reducers, bentonite expanders, and swelling inhibitors for 

water-sensitive clays. The selection of polymers ranges from low to medium molecular weight, and from moderate to very high anionicity.

2. Enhanced oil recovery (EOR): Injecting an aqueous solution with viscosity adjusted by a moderately anionic polymer to displace in-situ oil. The 

molecular weight of the polymer depends on the reservoir permeability and the viscosity of the in-situ oil.

3. Drag reduction: Using high molecular weight, moderately anionic polymers, due to their cohesive properties, can reduce friction and turbulence 

during high-velocity water injection.

4. Water sealing: This involves injecting a polymer solution to prevent water from flowing into the well. This polymer solution then forms a gel 

through in-situ cross-linking. The water permeability of the reservoir is altered through polymer adsorption on the rock without affecting oil 

permeability.

5. Oilfield produced water treatment: Polymers are often used in more conventional applications, such as centrifugal separation of oil and water, and 

water treatment before reinjection or discharge.