The following is the detailed role, usage, dosage and operation suggestions of polyacrylamide (PAM) in oilfield applications, subdivided according to different scenarios, for oilfield engineers' reference:

Enhanced Oil Recovery (polymer flooding)
effect
Viscous flow control: By improving the displacement water viscosity, reduce the water-oil mobility ratio, expand the sweep volume.
Improve displacement efficiency: Reduce the "pointing" phenomenon of the highly permeable layer and drive the crude oil in the low permeable area.

Usage
1. Solution preparation:
- Use anionic PAM (molecular weight 10 million to 25 million Da, hydrolysis degree 20% to 30%).
- When dissolving, it is necessary to slowly add to the mixing tank (speed 200~400 rpm) to avoid agglomeration, and the dissolution time is 1~2 hours.
- Formulation concentration: 1000~2500 mg/L (adjusted according to formation permeability).
2. Injection process:
- Continuous or slug injection through injection Wells, slug volume is usually 0.1-0.3PV (pore volume).
- The injection pressure should be lower than the formation rupture pressure (monitoring real-time pressure changes).

dosage
- Conventional reservoir: solution concentration 1000-2000 mg/L, injection rate 0.1-0.2PV.
- High temperature and high salt oil reservoir: salt-resistant PAM (containing sulfonic acid groups) is selected, and the concentration is increased to 2000-2500 mg/L.

Matters needing attention
- Prevent loss of viscosity by avoiding contact with high-priced metal ions (e.g. Ca² +, Mg² +).
- Filter the solution (5~10 μm filter) before injection to prevent particles from clogging the formation.

2. Drilling fluid additives
effect
- Increase viscosity and reduce fluid loss: improve mud viscosity, reduce fluid loss, and stabilize wellbore walls.
- Lubricate the drill: reduce the friction resistance between the drill bit and the wall.

Usage
1. Type selection:
- Non-ionic PAM (molecular weight 3 million to 8 million Da) is used in water-sensitive formations.
- Partially hydrolyzed anionic PAM (HPAM) for high solid phase mud.
2. Adding method:
- Directly added to the mud circulation system, preferally pre-dissolved in the slurry tank.
- Used in combination with bentonite and filtration reduction agent (such as PAC-LV).

dosage
- Viscosifier: 0.1%~0.5% (mass ratio, measured by mud volume).
- Fluid loss reducer: 0.05%~0.2%.

Matters needing attention
- Excessive addition may result in excessive mud viscosity and affect pumping efficiency.
- In high temperature environment (>120℃), temperature-resistant PAM (such as AMPS copolymer) should be selected.

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Third, produced sewage treatment
effect
Flocculation suspension: accelerate the sedimentation of oil and solid particles and purify water quality.
Demulsification: promote the agglomeration of emulsified oil droplets and improve the separation efficiency of oil and water.

Usage
1. Drug selection:
Oily sewage: cationic PAM (molecular weight 8 million to 12 million Da, charge density 20% to 40%).
Highly mineralized water: non-ionic or salt-resistant anionic PAM.
2. ** Dosing process ** :
- In the sedimentation tank inlet or in front of the air flotation device, mixed with inorganic flocculants (such as PAC).
Dosing concentration: 5~50 mg/L (adjusted according to water quality).

dosage
Conventional sewage: 20~30 mg/L (PAM), with 100~200 mg/L PAC.
High oil sewage: up to 30~50 mg/L, need to be optimized on site.

Matters needing attention
- The water temperature should be 25~50℃ during dissolution, and the dissolution time should be extended at low temperature.
- Avoid dosing with oxidant (e.g. ClO⁻) to prevent degradation.

Fourth, profile control and water plugging
effect
Blocking the highly permeable layer: The flow channel is blocked by gels or particles, forcing the displacement fluid to divert.
Control water and increase oil: reduce water production rate and improve oil well productivity.

Usage
1. System selection:
Weak gel profile control: PAM + aluminum citrate (crosslinking agent), gel formation time of 4~48 hours.
Particle plugging agent: PAM microspheres (particle size 0.1~10 μm, expansion factor 5~20 times).
2. Injection process:
Slug injection: pre-solution (5%-10% pore volume) → plugging agent (0.05%-0.2% PV) → post-solution.
The injection pressure is controlled at 70%~90% of the fracture pressure.

dosage
Gel systems: concentrations of PAM 3000~5000 mg/L and cross-linkers (Al³) 50~200 mg/L.
Microsphere plugging agent: injection concentration 0.5%~2% (mass fraction), dosage 50~200 m³/ well.

Matters needing attention
- The formation time should match the formation temperature (delayed crosslinker should be used in high-temperature reservoirs).
- The near well area should be cleaned before injection to prevent contamination.

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Five, fracturing fluid thickening agent
effect
Sand carrying: Increase fracturing fluid viscosity and suspend proppant.
Reduce resistance: reduce pipeline friction, reduce pump pressure.

Usage
1. Formula design:
Linear adhesive fracturing fluid: HPAM (molecular weight 5 million to 10 million Da) + anti-swelling agent (KCl).
Crosslinked fracturing fluid: HPAM + Borax (crosslinking agent, suitable for low temperature).
2. Preparation process:
Preparation of base solution: After PAM is dissolved, drainage aid and anti-swelling agent are added, and the viscosity is controlled by 50~100 mPa·s.
The crosslinker is mixed online before pumping.

dosage
Linear glue: PAM concentration 0.3%~0.8% (mass fraction).
Crosslinking system: PAM concentration 0.2%~0.5%, crosslinking agent 0.05%~0.2%.

Matters needing attention
High temperature reservoirs (>90℃) need to add temperature stabilizers (such as sodium thiosulfate).
After pressing, it is necessary to thoroughly break the glue (such as oxidizing glue breaking agent such as ammonium persulfate) to prevent damage to the crack conductivity.

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Sixth, anti-scale and slow
effect
Scaling suppression: Crystals such as CaCO₃ and BaSO₄ are dispersed to prevent line clogs.
Corrosion mitigation: adsorption film, isolation of corrosive medium.

Usage
1. Dosing method:
Continuous injection: PAM solution is injected into the produced liquid pipeline through a dosing pump (dosing point is located at the wellhead or gathering station).
Mixed with scale inhibitors (such as HEDP) and corrosion inhibitors (imidazoline).
2. Type selection:
Low molecular weight PAM (100,000 ~ 500,000 Da) is used to disperse scale crystals.

dosage
Anti-scale agent: PAM concentration 10~50 mg/L, with scale inhibitor 20~100 mg/L.
Corrosion inhibitor: PAM concentration 5~20 mg/L (auxiliary film formation).

Matters needing attention
- Regularly monitor the scale thickness and corrosion rate of the pipeline, and adjust the dosage concentration.
- Avoid direct mixing with cationic agents to prevent precipitation.

Seven, dosage and type selection quick reference table
| Application scenario | Recommended Type | Typical dosage | Key parameters |
| polymer flooding | salt-resistant anionic HPAM | 1000-2500 mg/L | molecular weight >18 million Da, hydrolysis degree 25%-30% |
| drilling fluid viscosity | non-ionic PAM | 0.1%~0.5% | molecular weight 3 million ~8 million Da |
| sewage treatment | cationic CPAM | 5~50 mg/L | charge density 20%~40% |
| Profile control and water plugging (gel) | Crosslinking HPAM | 3000~5000 mg/L | Gel forming time 4~48 hours (controllable delay) |
| fracturing fluid | linear adhesive HPAM | 0.3%~0.8% | viscosity 50~100 m Pa·s (170 s⁻¹) |
| anti-fouling | low molecular weight anion PAM | 10~50 mg/L | molecular weight 100,000 ~ 500,000 Da |
8. Operation standards and safety
1. Dissolution operation:
- Use clean water (avoid salt/impurities), stirring speed ≤500 rpm to prevent shear degradation.
- The solution temperature is recommended to be 25~50℃, and it needs to be preheated in winter.
2. Environmental requirements:
- Choose PAM products with low residual monomer (<0.05%), and discharge the waste solution after treatment.
3. Safety protection:
- Wear goggles and gloves during operation to avoid dust inhalation.

The above are the core application scenarios and engineering parameters of PAM in the oilfield, and the actual use needs to be combined with reservoir physical properties (temperature, salinity, permeability) and field test optimization and adjustment.