1. Surfactant for heavy oil exploitation

Due to the high viscosity and poor fluidity of heavy oil, it brings many difficulties to exploitation. In order to exploit these heavy oils, it is sometimes necessary to inject an aqueous solution of surfactants into the well to convert the high-viscosity heavy oil into a low-viscosity oil-in-water emulsion and pump it to the surface. Surfactants used in this thick oil emulsification and viscosity reduction method include sodium alkyl sulfonate, polyoxyethylene alkyl alcohol ether, polyoxyethylene alkyl phenol ether, polyoxyethylene polyoxypropylene polyene polyamine, polyoxyethylene Ethylene alkyl alcohol ether sulfate sodium salt, etc. The extracted oil-in-water emulsion needs to separate the water and use some industrial surfactants as demulsifiers for dehydration. These demulsifiers are water-in-oil emulsifiers. Commonly used are cationic surfactants or naphthenic acid, asphaltene acid and their polyvalent metal salts. For special heavy oil, conventional pumping unit extraction methods cannot be used, and steam injection is required for thermal recovery. To improve the thermal recovery effect, surfactants are required. Injecting foam into the steam injection well, that is, injecting high-temperature foaming agent and non-condensable gas is one of the commonly used modulation methods.

Commonly used foaming agents are alkylbenzene sulfonate, α-olefin sulfonate, petroleum sulfonate, sulfonated polyoxyethylene alkyl alcohol ether and sulfonated polyoxyethylene alkyl phenol ether, special gemini surfactants, etc. Because fluorine-containing surfactants have high surface activity and are stable to acid, alkali, oxygen, heat and oil, fluorine-containing surfactants are ideal high-temperature foaming agents. In order to make the dispersed oil easy to pass through the pore throat structure of the formation, or to make the oil on the surface of the formation easy to be driven out, it is necessary to use a surfactant called a thin film diffusing agent. Commonly used are gemini surfactants and alkylated phenolic resins.

 

2. The exploitation of waxy crude oil with surfactants requires frequent wax control and wax removal. Surfactants act as wax inhibitors and wax removers. Oil-soluble surfactants and water-soluble surfactants are used for wax prevention. The former plays a role of wax prevention by changing the properties of the wax crystal surface. Commonly used oil-soluble surfactants are petroleum sulfonates and amine surfactants. Water-soluble surfactants play a wax preventive role by changing the properties of waxing surfaces (such as tubing, sucker rods and equipment surfaces). Usable surfactants are sodium alkyl sulfonate, quaternary ammonium salt, alkane polyoxyethylene ether, aromatic polyoxyethylene ether and their sodium sulfonate salts. Surfactants for wax removal are also divided into two aspects, oil-soluble for oil-based wax removers, water-soluble sulfonate type, quaternary ammonium salt type, polyether type, Tween type, OP type surfactant, Sulfate ester salted or sulfonated flat addition type and OP type surfactants are used as water-based wax removers. In recent years, both domestic and overseas have organically combined wax removal and prevention, as well as oil-based wax remover and water-based wax remover, to produce a hybrid wax remover. This wax removing agent uses aromatic hydrocarbons and mixed aromatic hydrocarbons as the oil phase, and an emulsifier with wax removal function as the water phase. When the selected emulsifier is a nonionic surfactant with an appropriate cloud point, it can be made to reach or exceed its cloud point at the temperature below the waxing section of the oil well, so that the mixed wax remover can Before entering the waxing section, the emulsion is broken, and two kinds of wax removing agents are separated, and they play the role of wax removing at the same time.

 

3. Surfactant used to stabilize clay

The stabilized clay component prevents clay minerals from swelling and prevents clay mineral particles from migrating. It can be used to prevent clay from swelling, such as amine salt type, quaternary ammonium salt type, pyridine salt type, imidazoline salt and other cationic surfactants. Non-ionic-cationic surfactants containing fluorine are available to prevent the migration of clay mineral particles.

 

4. Surfactants used in acidification measures

In order to improve the acidification effect, a variety of additives are generally added to the acid solution. Any surfactant that can be compatible with acid and easily adsorbed by the formation can be used as an acidification retarder. Such as fatty amine hydrochloride, quaternary ammonium salt, pyridine salt in cationic surfactants and polyoxyethylene sulfonated, carboxymethylated, phosphate salted or sulfate salted in amphoteric surfactants Base phenol ether and so on. Some surfactants, such as dodecyl sulfonic acid and its alkyl amine salts, can emulsify the acid in oil to produce an acid-in-oil emulsion. This emulsion is used as an acidification industrial liquid and also has a slowing effect.

 

Some surfactants can be used as anti-emulsifiers for acidified liquids. Surfactants with branched structures such as polyoxyethylene polyoxypropylene propylene glycol ether and polyoxyethylene polyoxypropylene pentaethylene hexaamine can be used as acidification anti-emulsifiers. Some surfactants can be used as depletion aids, such as amine salt type, quaternary ammonium salt type, pyridine salt type, non-ionic, amphoteric and fluorinated surfactants.