Oil wells in the south of Saudi Arabia are mostly horizontal openhole (OH) completions. Some of these wells are dead or on intermittent production due to high water cut, owing to the influx of water through fissures or fractures. Overcoming this problem requires water shut-off (WSO), typically performed using mechanical and/or chemical barriers in the wellbore and/or reservoir. The WSO candidate well selection process starts with the evaluation of reservoir and production data, typically followed by a coiled tubing (CT) logging run to identify the water source and to help design the placement, formulations and volume of required isolating fluids. Water-producing zones can either be permanently isolated or shut-off temporarily while acid stimulation is applied to oil-producing zones. This study details the world’s first application of a fiber-optic CT logging in an OH completion for an oil well in Saudi Arabia enabled accurate evaluation of well conditions, depth control, and monitoring bottomhole parameters, to allow proper placement of WSO fluids into the target zone and isolate water producing intervals.