1.Surfactants for heavy oil extraction
Due to the high viscosity and poor fluidity of heavy oil, its exploitation is faced with numerous difficulties. To recover such heavy oil, aqueous solutions of surfactants are sometimes injected into the downhole. This process converts the high-viscosity heavy oil into oil-in-water (O/W) emulsions with low viscosity, which can then be pumped to the surface. The surfactants used in this heavy oil emulsification and viscosity reduction method include sodium alkyl sulfonate, polyoxyethylene alkyl alcohol ether, polyoxyethylene alkyl phenol ether, polyoxyethylene polyoxypropylene polyene polyamine, and sodium polyoxyethylene alkyl alcohol ether sulfate.
The oil-in-water emulsions produced need to be dehydrated to separate the water component, which also requires the use of certain industrial surfactants as demulsifiers. These demulsifiers are water-in-oil (W/O) emulsifiers, with commonly used types including cationic surfactants, naphthenic acids, asphaltenic acids, and their polyvalent metal salts.
For special types of heavy oil that cannot be exploited by conventional pumping units, steam injection is required for thermal recovery. To enhance the efficiency of thermal recovery, surfactants are needed. Injecting foam—i.e., injecting high-temperature-resistant foaming agents together with non-condensable gases—into steam injection wells is one of the commonly adopted techniques. The frequently used foaming agents include alkylbenzene sulfonate, α-olefin sulfonate, petroleum sulfonate, sulfonated polyoxyethylene alkyl alcohol ether, and sulfonated polyoxyethylene alkyl phenol ether.
Given their high surface activity and stability against acids, alkalis, oxygen, heat, and oil, fluorinated surfactants are considered ideal high-temperature foaming agents. In addition, to facilitate the passage of dispersed oil through formation pore throats or promote the displacement of oil from formation surfaces, surfactants known as film diffusing agents are employed, with the commonly used type being polyoxyalkylated phenolic resin polymer surfactants.
2.Surfactants for Waxy Crude Oil Recovery
For the recovery of waxy crude oil, wax prevention and wax removal operations must be carried out on a regular basis, where surfactants serve as both wax inhibitors and wax removers.
Surfactants for wax prevention fall into two categories: oil-soluble surfactants and water-soluble surfactants. The former exert their wax-inhibiting effect by modifying the surface properties of wax crystals, with petroleum sulfonates and amine-type surfactants being the commonly used types. Water-soluble surfactants function by altering the characteristics of wax-depositing surfaces (such as the surfaces of oil tubing, sucker rods and related equipment). Available options include sodium alkyl sulfonates, quaternary ammonium salts, alkane polyoxyethylene ethers, aromatic hydrocarbon polyoxyethylene ethers, as well as their sodium sulfonate derivatives.
Surfactants for wax removal are also divided into two types based on their application scenarios. Oil-soluble surfactants are incorporated into oil-based wax removers, while water-soluble surfactants—including sulfonate-type, quaternary ammonium salt-type, polyether-type, Tween-type and OP-type surfactants, as well as sulfate-esterified or sulfonated Peregal-type and OP-type surfactants—are used in water-based wax removers.
In recent years, both domestic and international industries have organically integrated wax removal with wax prevention technologies, and combined oil-based and water-based wax removers to develop hybrid wax removers. Such products employ aromatic hydrocarbons and mixed aromatic hydrocarbons as the oil phase, and emulsifiers with wax-removing properties as the water phase. When the selected emulsifier is a nonionic surfactant with an appropriate cloud point, the temperature below the wax-depositing section of the oil well can reach or exceed its cloud point. As a result, the hybrid wax remover demulsifies before entering the wax-depositing section, separating into two components that act synergistically to remove wax.
Post time: Jan-04-2026