From Drilling Stability to Enhanced Oil Recovery: PHPA Polymer Solution in a High-Salinity Oilfield
From Drilling Stability to Enhanced Oil Recovery: PHPA Polymer Solution in a High-Salinity Oilfield
Project Overview
A mature onshore oilfield in Central Asia faced operational challenges during both the drilling and production phases. The reservoir contained reactive shale formations and high-salinity formation water, creating instability during drilling and reduced efficiency during water flooding.
To address these issues, the operator implemented a tailored PHPA (Partially Hydrolyzed Polyacrylamide) polymer solutionfor both drilling fluid optimization and subsequent Enhanced Oil Recovery (EOR) Polymer Flooding.
Phase 1: Drilling Fluid Optimization
Background
During the drilling stage, the field encountered:
- Reactive shale formations prone to swelling and sloughing
- High salinity formation water (TDS approx. 65,000 ppm)
- Elevated torque and drag in directional sections
- Inconsistent mud rheology under circulation
Frequent borehole instability increased non-productive time (NPT) and raised operational costs.
Technical Challenge
The drilling fluid required a polymer additive capable of:
- Stabilizing reactive shale
- Maintaining viscosity in brine systems
- Reducing fluid loss
- Improving lubrication under high salinity conditions
Standard polymers showed partial viscosity degradation and insufficient Shale Inhibition performance.
Solution: Oilfield Grade PHPA Polymer
A high molecular weight PHPA polymer was introduced into the water-based mud system at a concentration of 0.2–0.3%.
Key mechanisms included:
- Polymer adsorption on shale surfaces to reduce hydration
- Encapsulation of drill cuttings to prevent dispersion
- Improved mud cake integrity to reduce filtrate invasion
- Formation of lubricating film to lower friction
Drilling Results
After implementation:
✓ Borehole Stability significantly improved
✓ Mud viscosity remained stable despite high salinity
✓ Torque and drag reduced by approximately 15%
✓ Non-productive time decreased by 12%
✓ No major shale sloughing incidents reported
The drilling phase was completed with improved efficiency and reduced operational risk.
Phase 2: Enhanced Oil Recovery (Polymer Flooding)
Following successful drilling operations, the field entered a tertiary recovery stage due to increasing water cut levels.
Reservoir Conditions
- Reservoir temperature: 78–85°C
- Formation water salinity: 60,000–70,000 ppm
- Mature water flooding with declining sweep efficiency
- Water cut above 85% in several production wells
The operator required a salt-resistant PHPA polymer for mobility control.
EOR Polymer Flooding Strategy
The same PHPA polymer platform was optimized for injection at concentrations between 0.1% and 0.25%, depending on permeability zones.
Objectives included:
- Increasing injection water viscosity
- Improving mobility ratio
- Expanding sweep efficiency
- Reducing early water breakthrough
EOR Performance Results
Within 9 months of Polymer Flooding:
✓ Oil production increased by approximately 8–12% in pilot wells
✓ Water cut stabilized and slightly reduced in targeted zones
✓ Injection profile became more uniform
✓ Sweep efficiency improved in heterogeneous sections
Reservoir monitoring confirmed improved displacement front stability and reduced channeling.
Technical Analysis
The success of the PHPA polymer solution was attributed to:
- High molecular weight structure for effective viscosity building
- Controlled hydrolysis degree for salt tolerance
- Strong adsorption properties for shale stabilization
- Stability across freshwater and brine systems
- Shear-resistant polymer chain structure during injection
This integrated approAch demonstrated the versatility of PHPA polymer in both drilling and EOR applications.
Client Feedback
According to the field technical manager:
"The PHPA polymer delivered stable performance under high salinity conditions and provided measurable improvements in both drilling stability and oil recovery. The adaptability of the polymer across different project phases reduced complexity and optimized operational efficiency."
Conclusion
This case study demonstrates how a properly selected PHPA Polyacrylamide Polymer can provide value throughout the lifecycle of an oilfield project:
- Improved drilling fluid performance
- Enhanced Borehole Stability
- Reduced operational risk
- Effective mobility control in Polymer Flooding
- Increased oil recovery in mature reservoirs
The project highlights the importance of selecting a salt-resistant, temperature-stable oilfield-grade PHPA polymer for integrated upstream applications.
Technical Support & Further Information
For detailed TDS, reservoir matching analysis, or customized polymer recommendations, contact Bluwat Chemicals. Our technical team supports oilfield operators with polymer selection, viscosity design, and application optimization.