From my experience, just getting good info on the value and the time of maximum production per field as well as an estimation of the average decline rate is enough to get a good approximation of the region production profile (see comment on Norway below). Now, you can develop a more sophisticated field model with a production plateau for instance but it does not imporve the result that much and requires much more information per field.

Agree as well. There is something to be said about not overanalyzing a specific region. The macro trends wash out any micro trends as you aggregate these smaller loglet or shocklet functions (loglet is Khebab's idea and I volunteer the shocklet to provide a mnenomic for the oil shock model)