A method includes controlling an oil and gas extraction process, controlling a production separation process, and controlling a de-gassing process. The method also includes optimizing the oil and gas extraction process, the production separation process, and the degassing process to optimize at least one process objective. The method could further include controlling a lift-gas compression process. The optimizing could include optimizing the lift-gas compression process, the oil and gas extraction process, the production separation process, and the degassing process to optimize the at least one process objective.