The problem with Beggs and Brill, Dukler, L&M, etc. for this particular application is they have no capability to deal with the oil-water physical and bulk properties, e.g. the oil viscosity or the emulsion phase viscosity. They assume a homogeneous liquid phase, which of course gross production is not. The best correlation is OLGA or one of the blackoil models embedded in PipePhase. These will get you a MUCH better ESTIMATE of the situation. And even then your calculated value will be ±20% at best.
I guess I would disagree about using Dukler or BBM for design purposes. I have done this exact work a ton of times and speak from experience. BBM, Dukler, etc. will get you a number for dP but you may be WAY off due to the reasons cited above. In my practice I would never use one of those for a gross production stream UNLESS I had bulletproof lab and/or field data that showed (1) there was virtually no emulsion phase (2) the tendency to form an emulsion is small (3) the nature of the liquid phase flow is well-known, i.e. oil-water slug or plug flow, or oil-water stratified.
If your need is critical I would find a consultant who has the Pipephase software. You should be able to get this calculation done for a few hundred bucks. Thanks!
Pete