LITRE METER
Specialist Flow Measurement Engineering
What Is Chemical Injection?
Chemical injection is a process designed to support oil production by injecting various chemicals into crude oil to provide a certain degree of protection. For example, a scale inhibitor prevents scale build-up in the pipes and fittings used to transport oil on its journey to the refinery. Flow meters are used to monitor and control the amount of chemicals added to the crude oil, while biocides prevent the build-up of organisms within the pipeline.
A corrosion inhibitor is the most commonly measured additive, although there are various types depending on the nature of the primary fluid. A pour point depressant is added to reduce the pour point, allowing the oil to flow more easily through the main pipelines. Most of the chemicals added are typically injected at low flow rates ranging from 0.01 to 40 litres per hour. LDHI (Low Dosage Hydrate Inhibitor) can have injection rates as high as 17,000 litres per hour. It is designed to inhibit water-based mixtures that would otherwise have a tendency to freeze.
With some Positive Displacement flow meters, a typical turndown ratio of 500:1 can be achieved. In general, these systems are relatively slow to respond dynamically and require only minor day-to-day adjustments, which is why manual controls remain popular. It is important that the flow measurement system for chemical injection can handle both the pulsating nature of the pumps used and the high pressures encountered. In modern subsea injection systems, these pressures can reach 1,380 bar / 20,000 psi / 20 ksi. Topside injection systems, on the other hand, typically operate at lower pressures ranging from 200 to 1,000 psi.
