Managing increasing volumes of produced water is one of the main challenges faced in waterflood fields. Better water mobility -compared to oil-, results in increasing water cut (WC) and reduced oil production, with time. In Qarn Alam, with mature brown fields depleted through waterflooding, oil producers are completed as open-hole horizontal wells. This means well experience water breakthrough from day one, due to poor oil-to-water mobility ratio, toe-heel effect, permeability variations and matrix fractures. Inflow Control Devices (ICD) has demonstrated good efficiency in delaying water breakthrough, however, when breakthrough is a given factor, ICDs lose that efficiency. The Autonomous Inflow Control Valve (AICV®) is a novel powerful tool that helps reducing WC in favour of oil, based on contrasts in fluid viscosities. The tool has a movable piston that opens/closes autonomously -without any connection to surface-, to reduce the unwanted water production, where choking increases with increasing WC. AICV technology was deployed in several oil producers, in carbonate reservoir brown field. The field has produced for decades, and is facing an increasing water management challenge. AICV completions were designed such that wells are divided into compartments isolated by swellable packers. The comparison of historical production data without and with autonomous inflow shows clearly the benefit of installing autonomous inflow control. Preliminary assessment showed an average 75% reduction in water-cut and 20% average increase in oil rate.