Choosing the right polymer for a specific reservoir and applying it at the right time is extremely important in maximizing oil recovery with polymer flooding. ZL was established in 1995, with a strong focus in polyacrylamide R&D and manufacturing for the enhanced oil recovery industry. We use our expertise, on-site experiences, and understanding of the reservoir to help our customers design the most cost effective program for their specific reservoir conditions. ZL works closely with E&P operators around the globe in every phase of a polymer flooding project, starting in the lab with polymer chemistry design and evaluation, pilot testing, and full field implementation.
Choosing the Right Polymer
Permeable low temperature reservoirs with low salinity formation water
Type I Polymers
Highly permeable formations with low bottom hole temperatures and low salinity formation water as typically ideal candidates for polymer flooding treatments. A hydrolyzed PAM (HPAM) is commonly used for such reservoirs.
A suitable chemistry for this reservoir type should have:
1) Linear structure
2) High viscosity in injection water targeted for use and in the presence of the formation water
3) Good dissolution with the injection brine targeted for use
4) Minimal adsorption tendency on formation rock
Permeable high temperature reservoirs with high salinity formation water
Type II and III Polymers
Reservoirs with high salinity formation water creates a challenging environment for most Type I Polymers, as they are not able to maintain a linear chain structure, which is needed for viscosity build and retention if it is to propagate effectively through the formation. High salinity also impacts the dissolution of HPAM, as in such environments it will take much longer to reach a full dissolution state, which would result in higher facility CAPEX requirements, and increased risk of injectivity issues over time.
High reservoir temperatures creates additional challenges for Type I Polymers, as polymer stability in-situ is impacted. Higher temperatures drives chemical reactions between polymers and divalent and/or multi-valent ions present in the formation water. High temperatures drives the hydrolyzes of such polymers which will change its viscosity behavior with the changing degree of hydrolysis.
Polymers need to be carefully selected for this type of reservoir to ensure technical success of a polymer flooding project. Polymers that are suitable for this type of reservoirs, ZLPAM Type II and III should have the following characteristics:
1) Linear structure
2) Low surface viscosity
3) Gradual viscosity build and retention in presence of formation water and higher temperatures
4) Good long term stability over time
5) Good dissolution with injection brine targeted for use
6) Minimal adsorption on reservoir rock
7) Good polymer displacement efficiency in the reservoir
8) Minimal emulsion tendencies with formation fluid
SP and ASP Flooding
Polymers for SP and ASP Fooding
Polymers selected for use in SP and ASP flooding should be compatible with surfactant and alkaline. ZL offers suitable polymers for both SP flooding and ASP flooding.
Offshore Polymer Flooding
TYPE IV and V Polymers
Application and deployment of polymer floods in offshore oil fields, is typically much more challenging compared to onshore. Limitations of deck space and weight, limited water source and waste water treatment facilities, large well spaces are often why implementation of a successful EOR program can be executed.
ZL's Type IV and V dry polymers includes polymer chemistries that are tolerant in high temperature and salinity environments and require little facility deck space and weight, such as ZL's ter-polymer chemistry, created using a micro block template. These polymers are able to quickly and fully dissolve in sea water and in high salinity water injection sources, eliminating the need for mixing and maturation tanks on the platform. Additionally, such polymers have good long term stability in-situ providing enhanced sweep efficiency and higher oil recovery.