Apparatus and associated methods relate to a decline curve analysis method for predicting oil and gas production from an oil well, where a prediction curve for oil and/or gas data transitions from a first characteristic function to a second characteristic function at the bubble point. In an illustrative example, the first and second characteristic functions may be of the monotonically decreasing type. A distinction between the two characteristic functions may be that the absolute value of the decline for the second characteristic function is greater than or equal to the absolute value of the decline of the first characteristic function for each value of time and/or cumulative oil/gas past the bubble point. In various embodiments, the method may give more accurate predictions for oil and/or gas production once the stimulated reservoir volume reaches the bubble point.
