Production Enhancement of an Oil Field using Integrated Modeling and Optimal Control

By continuous production of a hydrocarbon reservoir, the reservoir pressure and production rate decreases. If the gas oil ratio, flowing bottomhole pressure and reservoir fluid properties are appropriate, the production rate will increase with the use of the artificial gas lift. Gas lift operation must be monitored and injection conditions have to be updated with respect to the condition variation in order to obtain the optimum production rate and predict the performance of a hydrocarbon field. One of the problems which occurs in gas lift operations is the instability phenomenon. This phenomenon reduces oil production and damages facilities. Also, because of available lift gas limitation, the injection gas must be allocated among producing wells in a way to produce in an optimum condition and prevent instability. In the current study, Eclipse was used to simulate reservoir. Then, wells and surface flow pipeline network were modeled using Prosper. Eventually, MATLAB was used for connecting reservoir, wells and flow pipeline network to create an integrated model and allocate optimized lift gas rate between wells, by genetic algorithm. Injection gas was allocated among wells according to different scenarios. Moreover, oil production and cashflow from each scenario were compared. According to the results, using the integrated production model with the optimal control system in an artificial gas lift process improves cashflow by 224.86% over natural production condition in a hydrocarbon reservoir. Finally, although considering instability as a constraint in an optimal control system of integrated production model reduces cashflow by 2.93%, it will reduce the damage to the downstream facility in the long-term.