A method and system is provided that analyzes flow characteristics of return fluid that flows to a surface-located facility during well operations (such as plug mill-out or cleanout/workover operations) in order to characterize local formation properties of the formation. The method and system can be used to characterize a hydraulically-fractured hydrocarbon-bearing formation that is traversed by a well having a number of intervals that are hydraulically isolated from one another by corresponding plugs.