Enhanced Oil Recovery (EOR) helps operators squeeze more oil from mature fields, often boosting recovery by 10–20%.
But when the water used in polymer flooding contains very high salinity, things get complicated fast. Salt, especially calcium and magnesium ions, can weaken or even destroy polymer performance.
That’s why choosing the right polymer is one of the most critical steps in designing a successful EOR project.
In this blog post, we’ll look at why salinity matters, what makes some polymers better than others, and how UV-RAFT polymerization is changing the game.
Understanding How High Salinity Affects Polymers
When polymers are injected into reservoirs, they thicken water to push oil toward production wells. But in high-salinity water, their molecular chains shrink or break down. This leads to:
- Loss of viscosity → water moves too quickly, bypassing oil.
- Precipitation → polymers clump and block injectors.
- Faster degradation → shorter lifespan in the reservoir.
The end result? Higher chemical costs, lower oil recovery, and inefficient operations are issues.
What a “Good Polymer” Looks Like for Harsh Reservoirs
A high-performance polymer for EOR should be able to:
- Stay stable at high salinity levels (up to 150,000 ppm or more)
- Keep its viscosity even under pressure and temperature.
- Resist shear forces during pumping and injection.
- Work at lower concentrations to save costs.
Traditional polymers often struggle with one or more of these requirements. That’s where advanced chemistry steps in.
Common Polymer Options for Saline Fields
1. Sulfonated PAM (AMPS Copolymers)
Sulfonated PAM is a popular choice because it performs well in salty conditions.
Advantages:
- High resistance to calcium and magnesium
- Good thermal stability
- Cost-effective
Limitations:
- Viscosity can still drop in highly saline conditions.
2. Hydrophobically Associating Polymers (HAPs)
These polymers have small hydrophobic “anchors” that create temporary networks in water, keeping viscosity strong.
Advantages:
- Lower dosage needed
- Good viscosity control
- Useful for offshore operations with limited space
Limitations:
- Sensitive to shear during handling.
3. UV-RAFT PolyPAM
UV-RAFT (Reversible Addition–Fragmentation Chain Transfer) polymerization lets scientists build very uniform, high-performance polymer chains.
Advantages:
- Excellent brine tolerance up to 200,000 ppm
- Needs 20–40% less polymer for the same viscosity
- High thermal and shear stability
- Consistent performance over time
This technology doesn’t just improve the polymer; it improves the economics of EOR projects.
Best Practices for High-Salinity EOR Projects
Even the best polymer won’t work well without proper planning. To get the most out of your EOR project:
- Precondition the injection water to avoid ionic shock.
- Run lab and core flood tests to determine the best dosage.
- Monitor viscosity regularly to catch performance drops early.
- Adjust injection rates to maintain optimal mobility control.
These steps can help reduce waste, improve oil recovery, and extend project life.
Why Polymer Choice Matters for the Bottom Line
A strong, stable polymer can make a massive difference in overall project performance:
- Less chemical usage → lower costs.
- Fewer operational disruptions → better uptime.
- Better sweep efficiency → higher oil recovery.
In short, it’s not about using more polymer; it’s about using the right one.
Conclusion
High-salinity reservoirs used to be a significant barrier to polymer flooding. But with technologies like UV-RAFT PolyPAM, operators can now overcome these challenges.
This next generation of polymers delivers stronger performance at lower dosages, even in the harshest environments.
As oilfields become more complex, smarter chemistry is what will keep projects profitable and efficient.