This paper describes the success story of the first water shut off treatment using Engineered Micro-cement Slurry (EMS) through Coiled Tubing in Pakistan. The well was an oil well producing from multiple zones, but mainly the lower zone (C-Sand). Due to high water cut, it was decided to isolate the C-Sand and to produce only from the upper perforations (A/B Sands). Based on economics and technical feasibility, water shut off treatment through a cement plug was selected to isolate the C-Sand zone. 148ft of cement plug was squeezed and spotted across the C-Sand through coiled tubing using conventional cement slurry. After setting the cement plug, water cut was reduced by 23% and the well initially produced up to 380bopd from the A/B Sand. After 3 months production, water cut level increased drastically back to 100%. A slickline run confirmed that the cement plug had failed and top of cement dropped 48ft from its original depth. It was suspected that the plug failed due to possible contamination in the cement, which enabled water to channel up across the plug. A remedial cement plug through coiled tubing was subsequently set, but this time using EMS slurry to ensure that any channels in the previous plug were cemented and ensuring that the perforations were sealed off completely. The job was conducted successfully and the water cut was reduced by 25%, with initial production of 500bopd from the A/B Sands.

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