What is retention time? How is it calculated and measured?
Retention time is the time available for fluids to separate. It has been calculated by dividing the production rate into the storage capacity of any given vessel. For instance, a 1000 barrel tank processing 1000 barrels per day of fluid is said to have 24 hours (one day) of retention time. Actual retention times can be determined in the field by inoculating inlet fluids with a strong dose of a dye (oil or water soluble, depending one which retention time you seek). When the retention time of most oilfield vessels is measured, the actual retention time is usually less than 5% of the calculated time.
