Chemical injection is a process where various chemicals or solutions are injected into a system or substrate for specific purposes. This method is commonly used in a variety of industries, including oil and gas, water treatment, and construction, among others. The purpose of chemical injection can vary widely, including corrosion inhibition, scale inhibition, biocide treatment, and chemical reactions to achieve desired outcomes.

In the oil and gas industry, for instance, chemical injection is often used to treat produced water to remove impurities or to inhibit corrosion within pipelines and equipment. In water treatment applications, chemicals may be injected to adjust pH levels, remove contaminants, or disinfect water. In construction, chemical injection may involve injecting grouting compounds to stabilize soil or repair concrete structures.

The process typically involves specialised equipment for mixing and injecting the chemicals into the system or substrate, often under pressure, to ensure proper distribution and effectiveness. The choice of chemicals and injection methods depends on the specific requirements of the application and the desired outcomes.