Forecasting Exponential Decline

Production and Economic Forecast Using Exponential Decline forecasts production, revenues, and present value based on exponential decline. The exponential decline pattern for oil production is represented using the formula q = qie-at, where qi is the annual production for the first year and a is the (fixed) annual percentage decline rate. Uncertain input factors include 1) Yearly production (YrlProd), represented by Lognormal distribution; 2) Decline rate (Declrate), represented by Lognormal distribution; 3) GOR (constant Gas-Oil-Ratio), represented by Triangle distribution; 4) Price of gas, represented by Normal distribution; 5) Price of oil, represented by Normal distribution; and 6) Rate of increase of oil and gas prices, which are represented by Normal distributions embedded in the Revenue formulas. For each year, a new sample is drawn from a new Normal distribution, modelling variation from year to year. Outputs are defined as 1) Total NPV and 2) Oil-Gros, or production, for each year.