Is surface tension a good or bad thing? Role in oil and gas industries

The subject is so vast that we can very briefly touch the subject and only cover some key fundamentals and the important role of surface tension in the oil and gas industries as one example to limit the length of the document.

What does surface tension mean?

A liquid's ability to withstand forces from outside that might cause it to separate is a result of its surface tension. Simply put, it is the cohesive force that forms a thin layer on a liquid's surface and allows it to keep its shape and form.

The attractive forces between the liquid's molecules, which are stronger than the forces between the liquid's molecules and the gas molecules in the air, cause surface tension. As a result, the molecules of the liquid group together at the surface to reduce the amount of liquid that is exposed to the air. The tighter the molecules cling to each other, the greater the surface tension. The surface tension of a liquid is measured in units of force per unit length, such as dynes per centimeter or newtons per meter

Why should I be concerned as an engineer about surface tension?

Understanding surface tension is crucial for engineers working in a variety of fields, such as chemical, mechanical, materials science, and many more.?Surface tension is a phenomenon that happens at the interface of liquids, solids, and gases. It has significant effects on a variety of applications.

Engineers should take into account surface tension for the following reasons:

-Adhesion and wetting: Surface tension is a key factor in how liquids cling to and wet solid surfaces. This is crucial for adhesion, coating, and painting applications.

-Fluid dynamics: Fluid flow, shapes, and stability are influenced by surface tension and are crucial in many industrial processes, including oil extraction, cooling systems, and microfluidics.

-Materials science: Surface tension has an impact on how solids behave mechanically and how they react to stresses from the environment, such as breaking, fracture, and deformation.

Fundamentals:

There are two types of forces that act on a liquid-air interface [1] cohesive forces and [2 adhesive forces due to surface tension

?Cohesive forces

Due to intermolecular forces in liquid > air, the liquid molecules in the air-water receive a pull from inside the bulk of the liquid. This gives a curved surface at the interface. Water has a concave meniscus.

Adhesive forces

The intermolecular attraction between the liquid and the wall of the container generates adhesive forces.

Surface tension thus generates pressure at the interface

?The final shape of the curved surface depends on the net pressure acting at the boundary of the air-water interface after accounting for inside and outside pressure on the curved surface.

The pressure difference at the interface is called Laplace pressure

Laplace equation is ?P = y [1/R1 + 1/R2]

Where R1 and R2 are two radius curvatures.

The sign convention usually dictates positive curvature when convex and negative when concave.

When R1=R2, ?P = y =0

How do cohesive and adhesive properties affect flow fluid flow properties?

Cohesive properties

Because they control how well molecules adhere to one another and to the surface they are flowing over a substance's cohesive and adhesive properties have a direct impact on how well it flows.

Adhesive properties

They refer to the attraction between molecules that are dissimilar to one another, while cohesive properties refer to the attraction between molecules that are similar. For instance, water molecules can adhere to one another and create a cohesive unit because they are cohesive. Water molecules also have adhesive qualities that allow them to adhere to other surfaces, like the inside of pipes.

Overall, cohesive and adhesive forces have an impact on viscosity, or a fluid's resistance to flowing, which has an impact on flow properties. The fluid has a high viscosity and moves slowly when cohesive forces are strong. When adhesive forces are strong, on the other hand, the fluid has a tendency to adhere to the surface it is flowing over, causing friction and flow resistance.

Is surface tension a blessing or a curse?

?Depending on the situation, surface tension can be a blessing or a curse for the chemical industry.

On the one hand, because it permits some processes to take place, surface tension can be a useful property for the chemical industries. Surface tension, for instance, aids in preventing spills and leaks, which is crucial when handling dangerous chemicals. Additionally, it enables the creation of emulsions, which are crucial in the manufacturing of many goods, including food, medicines, and cosmetics.

On the other hand, because it can impede some processes, surface tension can also present difficulties for the chemical industries. For instance, it might be more challenging to evenly distribute and combine the ingredients in a solution or to apply a thin film to a surface. It may also cause issues when making products that need a high level of measurement accuracy.

Role of surface tension in Oil and gas industries

How does surface tension help?

Liquids' surface tension gives them the ability to withstand forces from outside that would otherwise try to separate them, such as stretching, bending, or compressing. The following are a few ways surface tension benefits these sectors:

-Prevents two-phase flow: Surface tension helps to prevent multiphase flow

-Controlling oil spills: Surface tension helps to keep oil spills in rivers, lakes, and oceans from spreading too far. By reducing surface tension, chemical dispersants, and surfactants also make oil break up into smaller droplets that are simpler to spread.

-Increased oil recovery: During oil extraction procedures, surface tension makes it easier for oil to move through reservoir rock pores.

-Drilling fluids: Drill cuttings are kept suspended and prevented from settling and obstructing the drill pipe by the surface tension of drilling mud. The surface tension of the drilling mud can be reduced by adding surface-active chemicals.

How surface tension can pose some challenges?

While surface tension has many advantages for the oil and gas industries, there are some drawbacks as well. Surface tension can present difficulties in these industries in a number of ways, including:

-Emulsions: Oil and gas products may develop emulsions due to surface tension, which can make it challenging to separate them. Emulsions can cause problems with production like corrosion, increased viscosity, and decreased effectiveness.

-Fluid flow: Surface tension can obstruct the movement of fluid in pipes and other machinery.

-Capillary forces: Surface tension can produce capillary forces in porous media, such as oil-bearing rock formations, which keep water and oil in the pores. These forces may make it challenging to extract oil and result in ineffective production.