A sand screen is a type of filter used to separate sand particles from other materials. It is often used in oil sands production, and allows users to harvest oil products without also collecting the sand nearby. These screens are also used on a smaller scale in many industrial and mining applications to separate sand from the material being collected. They are usually made of metal, and can vary in size depending on the application. While one sand screen may fit within a simple wheelbarrow, another sand screen may extend for thousands of feet (or meters) below the surface of the earth.
The most frequent application for sand screens is in oil production. Much of the world's crude oil and natural gas supplies are located deep underground, often in areas with desert-like conditions. Very large drills are used to bore below the surface of the earth in these areas to collect oil. A sand screen is often used to line the diameter of the bore, allowing oil and natural gases to filter through while keeping sand out of the bore hole. This helps prevent sand from getting into the drills, where it can slow production, or even render the drilling equipment unusable.
Sand control screens are typically made from stainless steel, which helps the screen hold up under harsh conditions. Stainless steel tends to perform much more effectively than other materials when exposed to natural gas or crude oil. It is able to resist rust and chemical corrosion, which helps to prolong the life of the screen.
A sand screen is typically categorized based on the size of the holes it contains, known as the "mesh." Each screen must be carefully chosen based on the size of the sand particles in each application, as well as on the thickness of and flow of the oil being collected. Too large of a mesh means that a larger quantity of sand will slip through the screen. If the mesh is too fine, however, production will be slowed, and the desired materials may not be able to seep through the screen. Many operations rely on a combination of screens with different mesh sizes to collect sand while allowing oil to flow easily into the bore.
Many drilling operations use an expandable sand screen that extends down the depth of the bore. These screens work like a telescope, allowing them to be set at a wide variety of sizes. As the drill passes deeper underground, the expandable sand screen is extended along its length, getting slightly narrower as it progresses. These screens allow workers to block sand even deep underground where a more traditional sand screen may not reach.