I'm in the water industry and we periodically have to design pipelines for supply to remote areas.  I know that the petroleum industry deals with long pipelines routinely.  I'd like to know what type of controls are generally used for booster pumping stations along the line.  And also, what's the typical distance before another booster station is needed?  I've used override control with discharge and suction pressure PID control but was wondering what the state of the art was in petroleum pipelines.