Optimal control strategies for oil production under gas coning conditions

Abstract

Gas coning, which can lead to gas breakthrough in thin oil-rim reservoir fields, may deteriorate economics in oil production. This work reports on optimal control policies to be considered for short-term oil production optimization under gas coning conditions. These policies, incorporating an oil-rate dependent Gas-Oil ratio model, are formulated as an optimal control problem which optimize the oil production rate, subject to gas processing capacity constraints. The result thereof is implemented in a closed-loop receding horizon control policy. Control philosophies investigated for increased oil production optimization include cyclic oil production shut-in at the vicinity of gas breakthrough (limiting the economic-deteriorating effects of excessive gas production, given gas processing constraints), and, steady oil production at-or after- the point of gas breakthrough. Near-well gas coning analysis reveals that gas coning dynamics may indicate which control philosophy (cyclic or steady oil production after process transients) may be optimal during closed-loop process operation.