Money, money, money – or, as we now call it, Flow Assurance, coupled with a low flow meter
Allowing scale to build up on the inside of the pipeline may seem fairly inconsequential. However, when the amount of scale is considered, (and referencing the image) it is immediately obvious that the expensive crude will slow down and pumping costs will soar. Sign up for FlowSight, the Litre Meter newsletter.
Chemists will analyse the crude oil as it comes out of the well, sometimes years before production starts. From geotechnical surveys other technicians will determine the rate of oil output through the anticipated life of the field. With this data the chemist will recommend what the concentration of the scale inhibitor should be. The pressure of the well will determine at which pressure the inhibitor needs to be injected at. Day to day the temperature will vary according to the seasons, the weather and location of the measurement.
The analysis of the crude, unrefined oil will tell the chemist whether the pipe will start to scale up as a result of pumping the oil through a pipe to the ship or refinery. Certain chemicals are then formulated to optimise and negate the scale. There will be compromises between concentration of the fluid, application flow rates and storage availability. If the concentration can be increased so that the tanks only need filling up once per month then that is preferred to once per fortnight. Inevitably this means that the flow rate is lower, and probably, the viscosity increases. Measurement range will also vary through the life of the field. It may start slow, then plateau a few years later and then tail off as the field winds down. Additionally to this, the consistency of the unrefined oil will probably change from start to finish. All of these variables can lead to a range of viscosities and a range of flow rates.
In summary, selection of the meter philosophy and specification is critical to successful measurement of scale inhibitor and future condition of the oil pipeline.
The VFF rotary piston flowmeter has been used for many years to measure scale inhibitor at a variety of flow rates, pressures and viscosities.