Apparatus and associated methods relate to computerized system for predicting the quantity of oil and/or gas production at an oil site, where a prediction curve for oil and/or gas data transitions from a first fitted curve (e.g., a hyperbolic decline curve) to a second fitted curve (e.g., an exponential decline curve) at a transition point, the transition point being determined by progressively/iteratively identifying curvature changes in the first fitted curve over an initial time period by comparing a running list of terminal decline rates (Dmin) with a predetermined curvature threshold, and setting the occurrence of the transition point at the point where the rate of change of the terminal decline rate is less than the predetermined curvature threshold. In an illustrative example, the second fitted curve may use the value of Dmin that minimizes the deviation between successive forecasts.
