Application of demulsification technology in oil fields

Demulsification refers to the complete breakdown of an emulsion, resulting in two immiscible phases. During oil extraction, changes in formation pressure, temperature, flow rate, and other factors can cause emulsions in crude oil to rupture, leading to the separation of oil, water, gas, and other components. This phenomenon is known as “demulsification.”

1. Demulsification mechanism

Demulsifiers are substances that disrupt the emulsion state of liquids and separate the phases. Their mechanism of action primarily involves reducing surface tension, disrupting the emulsion film, and altering surface charge. Surface tension is the intermolecular force on the liquid surface, maintaining the liquid’s surface morphology. Demulsifiers reduce the surface tension of the dispersed phase by altering it, causing the dispersed phase to aggregate, reducing droplet diameter, and promoting phase separation. Furthermore, they disrupt the emulsion film between the dispersed and continuous phases, formed by surfactants or colloidal particles, which stabilizes the emulsion. Demulsifiers can disrupt the emulsion film structure, making it unstable and thus achieving phase separation. Additionally, during emulsification, the surfactants or colloidal particles on the emulsion film surface carry charges, forming an electrical double layer. This creates electrostatic attraction between the dispersed and continuous phases, stabilizing the emulsion. Demulsifiers can alter the surface charge of the emulsion film, disrupting the electrical double layer structure, causing the dispersed phase to aggregate and separate.

In summary, demulsifiers can disrupt the emulsion state and achieve phase separation through various mechanisms. In magnetic-based nano-displacement agents, the role of demulsifiers is to cause the magnetic nanoparticles dispersed in the liquid to aggregate into larger clusters, thereby facilitating subsequent recycling and processing.

2. Advances in demulsification technology

Currently, based on their chemical structure, mechanism of action, and properties, demulsifiers can be classified into the following categories:

Inorganic demulsifiers mainly consist of substances such as acids, alkalis, and electrolytes. They disrupt the stability of the emulsion system by altering its pH value or electrolyte concentration. Inorganic demulsifiers are relatively inexpensive, but they can be corrosive to the environment and equipment.

Organic demulsifiers mainly include surfactants, solvents, and polymers. Surfactants break down emulsions by reducing the surface tension at the oil-water interface; solvents disrupt the stability of emulsions by dissolving or chemically reacting with emulsifiers; and polymers achieve demulsification by altering the structure of the emulsion system.

Biological demulsifiers : These mainly refer to demulsifiers derived from microorganisms or plants, such as enzymes produced by microorganisms or natural surfactants extracted from plants. Biological demulsifiers have advantages such as good biodegradability, environmental friendliness, and low toxicity, but their demulsification effect and stability are relatively low.

Compound demulsifiers : These combine two or more demulsifiers to improve demulsification effectiveness and adaptability. Compound demulsifiers can improve demulsification efficiency while reducing the amount of demulsifier used and minimizing environmental pollution.

Despite significant progress in demulsification technology, numerous challenges remain, such as the limitations of demulsifier performance, insufficient adaptability, and environmental impact. Demulsification can release large amounts of harmful substances into the environment, such as oily wastewater, organic matter, and heavy metals, severely impacting soil, groundwater, and surface water quality, causing lasting damage to the ecological environment. Harmful substances after oil-water separation may invade ecosystems, causing toxicity to plants and animals, damaging biodiversity and stability, and hindering ecosystem recovery and reconstruction. Furthermore, demulsification leads to the waste of petroleum resources, as some crude oil is difficult to recover after oil-water separation, increasing petroleum production costs and wasting resources.