Polyethylene glycol is a kind of non-ionic surfactant, has the properties of a general polymer, and also has the general characteristics of nonionic surfactants
1. Cloud point effect
After reaching a certain temperature, the polyethylene glycol solution will form turbidized microemulsion. The insoluble polyethylene glycol will block the pore throat of mud shale and prevent drilling fluid from entering the formation, so as to isolate drilling fluid from mud shale and stabilize the well wall.
At temperatures below the cloud point, aqueous solutions of polyethylene glycol and KCl remain inhibitive because their compounds prevent clay particles from coming into direct contact with water and prevent the hydration and dispersion of shale.
When the temperature is higher than the cloud point of solution, the higher the temperature is, the more polyethylene glycol will be precipitated, and the stronger the inhibition effect will be generated by plugging the cracks on the surface of clay particles.
When the temperature decreases, thepolyethylene glycol is completely dissolved.
2. Adsorption properties of clay
Temperature has the greatest influence on the adsorption capacity of polyethylene glycol, and the adsorption capacity increases with the increase of temperature.
When the cloud point temperature is below, the adsorption property of it on clay is similar to that of negative and cationic polymer treatment agent. When the cloud point temperature is above, the adsorption capacity on clay increases with the increase of temperature.
3 Interface activity
As a surfactant, polyethylene glycol has the critical micelle mass percentage and interfacial activity, which can significantly reduce the oil-water interfacial tension.
The increase of temperature or inorganic salt content has a synergistic effect on reducing the interfacial tension of oil and water
4. Interaction between polyols and organic macromolecules
Polyethylene glycol has good compatibility and can be used with different water-based drilling fluid systems.
When the inorganic salts are present, the viscosity of polymer aqueous solution is increased slightly.
The interaction between polyalcohol and organic macromolecules determines that polyethylene glycol is a non-ionic oligomer, which can be compatible with various electrical treatment agents.
5. Low fluorescence characteristics
The fluorescence level of 2% polyethylene glycoll was determined by fluorescence analyzer.It was much lower than the fluorescence level of drilling fluid lubricant
