The crude oil extracted from oil Wells is mainly composed of hydrocarbons, which contain paraffin in varying degrees and quantities. With the gradual decrease of mining pressure and temperature and continuous precipitation of gas, the solubility of wax in crude oil is also decreasing, and finally it is accumulated and deposited on the surface of the pipe wall. This "waxing" problem will seriously affect the production capacity of oil Wells and the quality of crude oil. So what are the reasons for this phenomenon?
1. Reasons for wax deposition in oil Wells
The external factors influencing oil well waxing include pressure, temperature, water in crude oil, colloid and asphaltene, mechanical impurities, oil flow velocity, pipe wall characteristics and so on. Among them, temperature and pressure changes are important influencing factors.
Oil well dewaxing and wax prevention technology and measures
1. Physical dewaxing and wax prevention
The so-called physical paraffin removal and paraffin prevention method mainly refers to the method of removing the paraffin which is adhered to the oil pipe wall and oil rod of an oil well through some effective physical measures.
1.1 thermal paraffin removal
Thermal dewaxing method mainly USES the principle of thermodynamics to increase the temperature of the fluid flow in the oil pipe and its deposition surface, so as to melt the paraffin deposited on the wall of the oil well pipe.
1.2 mechanical paraffin removal
Mechanical dewaxing method mainly USES special tools to scrape the paraffin adhered to the oil well tubing wall and carry it away by liquid flow, so as to achieve the purpose of dewaxing. Mechanical paraffin removal method has the advantages of simplicity, convenience and low cost.
1.3 strong magnetic wax-proof equipment
The strong magnetic wax-proof equipment makes use of the magnetic field to weaken the polymerization performance of paraffin molecules or molecular groups.
1.4 ultrasonic wax-proof technology
Under the action of ultrasonic wave, mechanical vibration will accelerate the relative motion of crude oil molecules, which will increase the friction between crude oil molecules, thus causing the long chain of paraffin hydrocarbon and asphaltene macromolecular chain to break, through the destruction of molecular groups to affect the speed and number of paraffin deposition.
2. Chemical paraffin removal and wax prevention
2.1 chemical wax repellent
The application of some chemical paraffin inhibitor in oil pipe can effectively inhibit the precipitation, aggregation and deposition of paraffin crystals on the surface of oil well. The three most commonly used wax-proofing agents are surfactants, polycyclic aromatic hydrocarbons and polymeric wax-proofing techniques. Surfactants can be divided into oil solubility and water solubility, and their mechanism of action is different.
2.2 chemical paraffin remover
Chemical dewaxing method mainly USES the heat energy generated in the process of chemical reaction to remove the blockage of paraffin wax. For example, aluminum, sodium hydroxide, magnesium and hydrochloric acid react to produce a lot of heat. Its drawback is not economic, the effect is poorer. At present, the dewaxing agents used in chemical dewaxing mainly include oil-based dewaxing agents, emulsion dewaxing agents and water-based dewaxing agents.
In a word, oil well dewaxing and wax prevention play a vital role in oil well exploitation.