I. Polyacrylamide (PAM) for Drilling
Polyacrylamide (PAM) is a water-soluble polymer with both stability and multifunctionality. It is normally a white powder or granules. Because its molecular chain is rich in active amide groups, it can be adapted to the drilling needs of different oilfield formations by adjusting key parameters such as molecular weight (generally 1.0×10⁶～5.0×10⁶ for drilling applications) and degree of hydrolysis. As a core additive in drilling fluid systems, it features low dosage (typically added at 0.5%～1.2%), excellent effects, and adjustable temperature and salt resistance. It can significantly improve the safety and efficiency of drilling operations and is an indispensable “technological aid” in oilfield development.
II. Core Roles in Drilling
Adhesion and Cutting Carrying: An “Efficient Transport Vehicle” for Cuttings
During drilling, broken cuttings can easily become stuck downhole, leading to stuck drill bits and drill bit wear. PAM (Polymerized Aluminum Ammonium Dioxide) increases the viscosity of the drilling fluid, giving it strong suspension and carrying capacity. Simultaneously, its unique shear-dilution properties—viscosity decreases under the shearing action of the high-speed rotation of the drill bit, reducing flow resistance; viscosity recovers rapidly during ascent, ensuring that cuttings do not settle and are efficiently transported to the surface, guaranteeing smooth drilling and reducing energy consumption.
Anti-Collapse and Well Protection: A “Safety Shield” for the Wellbore
Drilling deep wells and complex formations (such as shale formations) presents a common challenge in the industry, as rock formations are prone to hydration, expansion, and collapse upon contact with water. PAM molecules can adsorb onto the surface of the rock in the wellbore, forming a dense and uniform filter cake. This effectively prevents drilling fluid filtrate from seeping into the formation, inhibiting rock expansion and disintegration, reducing the risk of well collapse, and protecting underground oil and gas reservoirs from contamination, significantly improving wellbore stability.
Lubrication and Drag Reduction: Equipment “Maintenance Agent”
When drilling fluid circulates in downhole pipelines, it rubs against the pipe walls and drill bits, consuming a significant amount of power and accelerating equipment wear. PAM’s polymer chains can form a lubricating film on metal surfaces, reducing frictional resistance. Especially in long-distance drilling scenarios such as horizontal wells, it can reduce pump pressure by 20%–30%, saving energy, extending the service life of drill bits and pipelines, and lowering maintenance costs.
III. Selection and Usage Considerations
- Molecular Weight Matching: For shallow, loose formations, medium molecular weight PAM (1.0×10⁶–3.0×10⁶) is suitable, focusing on flocculating rock cuttings; for deep, dense formations, high molecular weight products (3.0×10⁶–5.0×10⁶) are required to enhance viscosity and prevent collapse.
- Resistance to Deterioration: Ordinary PAM can be used in conventional formations; for high-temperature (100–200℃) and high-salinity formations, hydrophobic associative or AMPS copolymer-modified products are required to resist damage from high-valence cations (calcium and magnesium ions) and maintain performance stability.
- Correct Use: Prepare a 1% aqueous solution first, thoroughly stir to dissolve, and then add to the mud pit. Avoid direct mixing with bentonite, which can cause clumping. The functional emphasis can be adjusted according to the mud’s specific gravity—for specific gravity less than 1.07, it focuses on settling rock cuttings; for specific gravity greater than 1.10, it focuses on thickening and stabilizing flow. It must also meet relevant industry quality standards.
IV. Industry Applications and Trends
PAM is widely used in the oilfield sector. It is not only an essential component of drilling operations but also plays a crucial role in tertiary oil recovery in older oilfields. By increasing the viscosity of the injected fluid and expanding the swept volume, it can increase crude oil recovery by 10%–30%, contributing to increased oilfield production and efficiency.
With increasingly stringent environmental requirements, PAM is developing towards green and intelligent technologies: Bio-based PAM uses renewable raw materials to replace petroleum-based monomers, reducing carbon emissions; photosensitive and temperature-sensitive controllable degradation products can achieve targeted degradation after downhole operations, reducing environmental pressure; combining digital technology for precise dosage control ensures effectiveness while reducing wastewater treatment costs, achieving a win-win situation of high efficiency and environmental protection.
V. Cross-industry Application Value
Besides oilfield drilling, PAM, with its flocculation, thickening, and stabilizing properties, is also widely used in wastewater treatment (flocculation and clarification of industrial wastewater and domestic sewage), agriculture (soil retention, slow release of water and fertilizer), construction (thickening and crack resistance of cement mortar), and pharmaceuticals and daily chemicals (thickening agent for cosmetics, drug slow-release carrier), becoming a universally applicable polymer material across industries, demonstrating its diverse application value and role.