Predicting Transition to Turbulence in Well Construction Flows

摘要

Two classical geometries for wellbore hydraulics are the pipernand the plane channel, (often approximating an annulus). Therntechnical literature is full of semi-empirical methodologies forrncomputing frictional pressure losses and flow regimes in theserngeometries and there is much confusion about both the validityrnand physical basis of many of these phenomenological criteria.rnIn this paper we examine phenomenological criteria forrntransition, in the context of newly derived theoretical resultsrnon stability of these flows. We examine five transitionalrncriteria commonly used in the petroleum industry and are ablernto rigorously demonstrate that only one of the five criteria canrnpossibly be correct over the full range of Bingham numbers.rnWe then examine a more limited, but relevant, range ofrnBingham numbers and show that enormous discrepancies existrnbetween these criteria. We conclude by discussingrnimplications for current practice.