شهلا خالقی

After the oil shocks of the 70s، oil extraction policy has become more important in two aspects. In one aspect، economists have reconsidered the Hotelling (1931) model about optimal natural resource extraction rate and in other aspect، engineers has paid more attention to enhanced oil recovery (EOR) methods. Economic theory of natural resources extraction is designed for maximization of discounted profit but in engineering point of view enhanced oil recovery with considering maximum efficient rate (MER) shape the optimal extraction rate. As a result، combination of these important economic and engineering concepts could be comprehensive definition of the optimal oil extraction rate. This idea has been investigated for one of the southwest Iranian oilfield where natural gas injection as an EOR method has been applied. In this study، we have utilized the optimal control theory which considers all of the above mentioned assumption. The results about cost function indicated that oil extraction cost increases with decreasing remaining reserves. Result about optimal extraction rate showed that for discount rate higher than 10 percent، extraction rate has not been dependent to three EIA oil price scenarios. Optimal oil extraction model depends on discount rate. Low dependency to the oil revenue leads to conservative extraction but otherwise maximum extraction in early years and minimum extraction in the latest years would be optimal.