Polyacrylamide (PAM), with its thickening, flocculating, drag-reducing, and profile-adjusting properties, is widely used in oilfield drilling, well completion, oil production, and water treatment. Its core value lies in improving operational efficiency, protecting reservoirs, and enhancing oil recovery. The following are its main application scenarios, mechanisms of action, and key technical points:

1. Drilling Fluid Additive
PAM ensures safe and efficient drilling by adjusting drilling fluid rheology, reducing filtration loss, and stabilizing shale.

**Viscosity Enhancement and Cutting Carrying:** Increases drilling fluid viscosity and suspension capacity, efficiently carrying cuttings and preventing settling during circulation shutdowns, optimizing rheology to adapt to different operating conditions.

**Filtration Loss Reduction and Wellbore Stabilization:** Forms a dense filter cake on the wellbore, reducing filtrate intrusion, inhibiting clay hydration and swelling, and lowering the risk of well collapse and stuck pipe.

**Shale Inhibitor:** Partially hydrolyzed polyacrylamide (PHPA) adsorbs clay particles, preventing water molecules from entering the interlayer, making it particularly suitable for water-sensitive shale formations.

Flocculation and purification: Removes inferior solid phases from drilling fluid, reduces reservoir damage, and achieves green drilling.

2. Tertiary Oil Recovery (EOR) Polymer Flooding
Polymer flooding is a core technology for improving oil recovery, expanding swept volume by improving mobility ratio.

Mobility control: Increases injected water viscosity, reduces aqueous phase permeability, slows fingering/tongueing, and improves planar and vertical swept efficiency.

Expanded swept volume: Enables uniform propagation of the displacement fluid, contacting more remaining oil, increasing recovery by 8%-25% (conventional HPAM approximately 8%-12%, hydrophobic associative types can reach 18%-25%).

Temperature and salt resistance modification: Partially hydrolyzed polyacrylamide (HPAM): Suitable for medium-low salinity (<10⁴ mg/L), medium-low temperature (<90℃) sandstone reservoirs, with a degree of hydrolysis of 20%-30%.

Hydrophobic Associating Polyacrylamide (HAPAM): Introduced with hydrophobic groups, it withstands temperatures up to 120℃ and salt concentrations up to 20×10⁴ mg/L, making it suitable for high-salt or high-temperature heavy oil reservoirs at sea.

Implementation Process: Pre-plug → Main polymer slug → Subsequent protection slug, combined with profile control and water shut-off to enhance the effect.

3. Fracturing Fluid Additives

PAM is used for drag reduction in slickwater and thickening of cross-linked fracturing fluids, improving fracturing efficiency and protecting the reservoir.

Drag Reduction Agent: Anionic PAM reduces friction in slickwater (by 60%-80%), increasing flow rate and reducing pump pressure, suitable for large-scale volumetric fracturing.

Thickening and Props Carrying: Cross-linked PAM (such as boron-cross-linked HPAM) forms a highly viscoelastic gel, suspending proppant and creating a complex fracture network. It can be controlled to degrade after operation, reducing damage.

Clay Stabilization and Swell Prevention: Inhibits clay swelling during proppant flowback, maintaining fracture conductivity.

4. Water Shutdown and Profile Control: Blocks high-permeability flow channels, improves the injection profile, and enhances water drive efficiency.

Profile Control: By selectively blocking high-permeability layers, it forces injected water to flow towards low-permeability layers, expanding the affected area.

Water Shutdown: Forms gel or sediment in the production section, reducing water cut and extending the waterless production period.

Process Types:
Polymer Gel Water Shutdown: PAM forms a gel with crosslinking agents (chromium, aluminum, phenolic, etc.), providing high sealing strength and long-lasting effectiveness.

Foam-Polymer Composite Water Shutdown: Suitable for high-temperature, high-salinity formations, reducing filtration loss and improving sealing selectivity.

Application Timing: High water-cut wells with a water cut > 85%, or well groups with low water drive efficiency.